The Garden Shed

A Community Newsletter published by the Piedmont Master Gardeners

October 2016-Vol.2 No.10

 

For comments, questions or suggested topics for future Garden Shed articles contact us at: garden-shed@piedmontmastergardeners.org.

If you have specific gardening questions or need help to solve a gardening problem, our Horticultural Help Desk is a free community resource and can be contacted at 434-872-4583 or by email: albemarlevcehelpdesk@gmail.com.


The Garden Shed- Who We Are

Who We Are

We are members of the Piedmont Master Gardeners, which simply means we have all been trained to share the scientific expertise of Virginia Tech and the Virginia Cooperative Extension Service. More important, we are your friends and neighbors with a passion for gardening – and learning more about it. MORE

Table of Contents

Flourless Brownies

You'd never guess the secret ingredient in this moist GF brownie!

The Ornamental Garden in October

October is when the ornamental garden explodes in a riot of color.

Interpreting Your Soil Test Report

Well, it might as well been written in Greek or Chinese.

The Vegetable Garden In October

October is paranoia season.

White Oak — A Majestic Native Species

The white Oak is one of America's most majestic native species.

My Peony Adventure

Family heirlooms.

My Peony Adventure

Every spring I await the spectacular white blossoms from a single tree peony planted by my mother almost 50 years ago.  Family lore says these flowers are notoriously hard to transplant; so I left it alone despite the bruising it gets from growing near the shed door beside a path.  That lore was severely tested last winter when my neighbor gave me enough peony crowns for seven plants.

For 35 springs this man and his wife had watched with pride as the gift of his mother-in-law’s peonies bloomed in their back yard.  Now the precious heirlooms had to be moved and quickly before the sale of their home.  A January evening found him furiously digging in his new yard as many holes for them as he could.  Following directions for a deep, well-drained bed, he made 18 holes in the red clay 24 inches deep and 12 inches across.  Each hole got a generous helping of composted manure.  As the winter sun went down, the precious florae settled into their new home with their tender eyes or growing tips buried no more than two inches deep.  When he was out of time and energy that cold evening, I went home with a bucket of bare-root specimens.

A little research revealed the difference between the so-called tree peony my mother planted and the castoff perennial peonies that I placed in a large tub and covered with mulch.  Tree peonies are a woody shrub, living as long as 100 years, and the bare branches should never be cut down.   The leaves are more dull, but flowers are larger and flatter than herbaceous perennial peonies.  Perennial peonies like their cousins are long-lived but die back with the first good frost.  The latter grow slowly and can spread 3-5 feet needing that much space between specimens as well.

Once established, with six hours of full sun and little competition from other plants, these perennials require little attention.  However, the process of moving can be as traumatic for peonies as it often is for their human caregivers.  Our friend had done his homework.  Each mass of roots with their tender buds sits just under the surface.  Because they cannot stand wet feet, a deep, loose bed is necessary.

I needed more information about caring for these beauties. The genus Paeonia is said to have originated in China where petals have been used medicinally and for tea.  Missionary descriptions and Chinese art familiarized Americans with peonies before the plant itself was introduced.   It includes both tree or shrub peonies which can reach 6-7 feet in height (sometimes referred to as moutan) as well as the more common herbaceous perennial peonies.  They all prefer a slightly alkaline soil and benefit from topdressing with bone meal, compost or an organic fertilizer low in nitrogen.  Overfeeding can make for luscious greenery with no blooms. The tree peony particularly may take several seasons to mature enough to flower.  The perennials I transplanted made foliage almost a foot high with a few buds in the first spring; but they produced no flowers.

Although they need water, especially early in the season,   do not wet the base.  Apply water around the drip line.  Light shade can be helpful and protection from heavy winds will keep it from losing petals.  Staking perennial peonies keeps them from drooping and allows good air circulation. Disbudding, or removing smaller side buds, will encourage a peony to produce fewer large blossoms for cutting.   Fall is a good time to apply mulch, keeping the mulch away from the stem to discourage fungus.

Perhaps the most likely problem is botrytis blight in the spring resulting in wilted stalks and blackened buds.  Sucking thrip damage can be distinguished from blight by holding a white paper beneath the leaves and tapping the plant.  The thrips will fall into the paper.  Blight can be treated with fungal sprays on the leaves and/or soil, but remember not to use copper if the temperature is over 85 degrees.  Infected plant parts should be cut off and cleaned away as soon as injury is spotted.  At the end of the season, rake up dead foliage and discard it to prevent blight from carrying over to the following year.

Dividing peonies is best done in late summer or autumn.  The root consists of two parts, a crown from which will come new growth and the many long, thin feeder roots spreading from the crown.  Your goal is to cut a pie-shaped segment of the crown with lots of 8-10 inch long feeder roots.  Each piece should have 1-3 buds.  The trick is to get the right balance of root to top growth.  Over fall and winter, the roots are storing food which will be used in spring for growth and flowering.  If you must dig up a root with leafy shoots attached, replant promptly providing shade.   Either by instinct or the memory of his mother-in-law’s instruction, my friend had dug and divided his roots very well.

Despite initial ignorance on my part, the perennial peonies did well for both my neighbor and me.  Waiting for them to mature and blossom is an ongoing challenge.  So far the rapacious deer in our neighborhood have not touched them.  That in itself is a reason for patience.

References

“Botrytis Blight of Peony,” Mary Ann Hansen,   https://pubs.ext.vt.edu/450/450-602/450-602.html

“Perennials: Culture, Maintenance and Propagation,” Diane Relf, http://pubs.ext.vt.edu/426/426-203/426-203_pdf.pdf

“TREE PEONIES,” Jerry Meyer and Leonard P. Perry, http://www.uvm.edu/~pass/perry/trpeony.html

“Care Calendar,” The Peony Garden, Nichols Arboretum, University of Michigan. http://peony.mbgna.umich.edu/care-calendar

Simon and Schuster’s Guide to Shrubs and Vines, Costanza Lunardi, 1987.

http://www.hollingsworthpeonies.com

 

 

Flourless Brownies

As the owner of a small catering business, I am regularly asked to meet special dietary needs. Having tried countless gluten-free (GF) desserts, I find many of them to be bland and dry.  Page after page of my GF cookbooks are marked with a giant X through them, obliterating one disappointing recipe after another.  So, when a recent client asked me to prepare the following gluten-free dessert bar for a special event, I was understandably dubious. “Trust me. They’re delicious,” she said. “And you’d never guess the secret ingredient!”

She was right. I would never have guessed. Check out the first ingredient below and I imagine you will be as surprised as I was to learn what makes this gluten-free confection so wonderfully moist. I baked them right away and all it took was one bite for me to declare them the best flourless brownies I have ever eaten. You needn’t be on a gluten-free diet to enjoy these easy-to-make brownies. Top them with a scoop of ice cream and you’ll add them to your list of favorite indulgences.

black-bean-brownies

The following recipe is courtesy of Whole Foods Market.

Ingredients

1 15 oz. can of black beans (no salt added), drained and rinsed

3 large eggs

1/3 cup melted butter

1/4 cup cocoa powder

1/8 teaspoon salt

2 teaspoons gluten-free vanilla extract

1/2 cup, plus two Tablespoons, cane sugar

1/2 cup semi-sweet chocolate chips

1/3 cup finely chopped walnuts

 

Directions

Preheat oven to 350 degrees. Butter 8×8-inch baking pan. Place black beans, eggs, butter, cocoa powder, salt, vanilla, and sugar in the bowl of a food processor and blend until smooth. Remove the blade and gently stir in the chocolate chips and walnuts. Transfer mixture to the prepared pan. Bake 30 to 35 minutes, or until just set in the center. Cool before cutting into squares.

 

The Vegetable Garden In October

I often associate the months of the year with the seasonal tasks to be performed in the vegetable garden. I usually think of the months of April–May as the planting season, while June–July is the growing season with its maintenance tasks of weeding and watering; August–September is the harvesting season, and October, well, that is my “paranoia” season.

October is paranoia season because in our area, it is the first frost month — usually around the 15th of the month. It can arrive earlier or later, but we know it is going to happen; we just don’t know exactly when. I always have peppers needing just a little more time to turn to that brilliant red or perfect golden yellow, or tomatoes on one plant or the other that are slow in ripening, or that one lettuce bed that is just starting to rock, so I am glued to the weather report, trying to catch that first freeze warning. I can’t count the times we’ve had a frost, and then right afterwards, Indian summer shows up smiling and bringing temperatures in the 70s and 80s for a couple of weeks after all the frost damage is done. I have finally come to the conclusion that waiting for that freeze warning is too late because there are precautions that can be taken to extend the growing season before that dreaded frost forecast.

There are two types of frost, advective and radiation. Advective frost occurs when a cold front sweeps into an area. A radiation frost occurs under calm winds and clear sky, allowing radiant heat from the earth to rise to the upper layers of the atmosphere. With radiation frost, the lack of wind prevents mixing of the air and an inversion develops. An inversion is just a fancy way of saying “things get turned around from the normal.” Normally the air closest to the ground is the warmest, but when an inversion happens, cold air collects near the ground while the warmer air lies above the trapped cold air. During an inversion, cold air is just like water running down a hill — it seeks the lowest point because it is heavier than warm air, and frost pockets may form. The first frost typically is a radiation frost that occurs on a calm, clear night.  

There are several things we can do when a frost warning is issued:

Harvest early: Flowering plants such as beans, tomatoes, peppers, eggplant, squash and okra need to be harvested if there is no way to protect them. Fruit harvested in the mature green stage will still ripen, but sadly will not have the same flavor as a vine-ripened fruit.

Water before a frost: Moist soil can hold approximately four times more heat than  dry soil. Moist soil can also conduct heat to the soil surface faster than dry soil, providing some frost protection. A Cornell University study suggests that the air temperature above a wet soil is 5° F higher than that above a dry soil, and in the study, that difference was maintained until 6 a.m. The conclusion of this study was that plants could benefit from watering the evening before a frost.

Cover your plants: A cover can provide anywhere from 2º to 6º F of protection, depending on the type of material used. The covers can be laid right on top of the plants or can be supported by stakes or a frame, the main difference being that there is less frost protection when the cover touches the plant. Any material can be used as cover; however, woven fabrics are better insulators than plastics or paper. The best time to apply covers is in the late afternoon after the wind dies down. Remove the covers the next morning.

 

"Hoop-House" with plastic being used for frost protection

“Hoop-House” with plastic being used for frost protection

Row cover provides 2-3 degrees F frost protection

Row cover provides 2º to 6º F of frost protection

 

 

 

 

 

 

 

 

Additional Tips and Tasks for October:

  • Plant garlic and shallots to harvest next year.
  • Harvest tender herbs (basil) before the first frost. They can be hung to dry in a cool dark place or the leaves can be frozen for use at a later time.
  • Thinking about planting a fruit tree? Fall is usually cool and moist and a great time to plant. In addition, you may be able to save a little money, as local gardening centers usually have a fall sale. Water the newly-planted tree to provide sufficient moisture and prevent winter damage. Add a 3-inch layer of organic mulch, such as shredded bark around the base of the plant to retain soil moisture and regulate soil temperature. Research has shown that roots will continue to grow until the soil freezes, which is around late November in Virginia. Stake and wire newly-planted trees only if necessary. Use a piece of rubber hose around the guy wires to protect the trunk. The guy wires should be tied loosely enough so that the tree is able to move a little in the wind. The supports and stakes should be removed once the tree becomes established, usually in a couple of months. (Relf)
  • Fall is an excellent time for taking soil samples in your garden. Soil test measures the pH (acidity or alkalinity) of the soil and the levels of some of the major elements required for plant growth, such as phosphorus and magnesium and potassium. If lime is required to adjust the pH, now is a good time to apply it. A free soil test kit is available from your local extension office.
  • Pick up dropped fruit from under fruit trees so that deer and rodents will not be attracted to the fruit  — AND to your growing tree. Raking and disposing of diseased leaves will help keep insects and diseases under control next season.
  • High grass and mulch are a haven for rodents whose gnawing can severely damage trunks. Keep the grass mowed around new trees.  Be sure that mulch is raked back 3-4 inches away from the tree trunk.
  • Tomatoes need an average daily temperature of 65º F or higher in order to ripen. If daytime temperatures are consistently below this temperature, pick the fruits that have begun to change color and bring them inside to ripen.
  • Harvest sweet potatoes before frost because cold soil temperatures can reduce the quality and storage capacity of sweet potatoes. I find that removing the vine first makes the digging a lot easier. Also, care should be taken when digging sweet potatoes because they skin and bruise very easily.
  • When removing disease-infested plants or debris, do not place this refuse on the compost pile. The disease pathogen may continue to live in the compost pile and may be transmitted when the compost is applied to the garden.
  • After frost, cut back all the foliage of asparagus to within 2 inches of the ground.
  • There is still time to plant a winter rye cover crop. A cover crop protects the soil over the winter, traps any unused nutrients to prevent them from leeching, and adds organic matter in the spring when tilled under.
  • It’s not too early to start thinking about next year’s garden. An excellent tool for planning is a garden sketch of this year’s crop locations. This will help when you’re deciding  which crops you need rotate to minimize disease problems. Vegetables crops in the same botanical family are often susceptible to the same diseases and insects. For crop rotation to be effective, gardeners should not plant vegetables belonging to the same family in the same location for at least two or three years. Obviously, crop rotation in a small garden may be difficult. However, we should rotate our vegetable crops as best we can.

 

Sources:

Phillips, Ben, “Freeze Damage in Fall Vegetables: Identifying and Preventing,” http://msue.anr.msu.edu/news/freeze_damage_in_fall_vegetables_identifying_and_preventing

“Understanding Frost,” Cornell Cooperative Extension, http://www.gardening.cornell.edu/weather/frost.pdf

Relf, Diane, Virginia Cooperative Extension, “The Virginia Gardener Newsletter,”Volume 23, Number 9/10, 2004, page 7.

Clemson Cooperative Extension, Publication HGIC 1322, “Sweet Potato,”http://www.clemson.edu/extension/hgic/plants/vegetables/crops/hgic1322.html

Virginia Cooperative Extension, Publication 426-401, “Asparagus”, http://pubs.ext.vt.edu/426/426-401/426-401.html

Colorado State University, Publication GMG #722, “Frost Protection and Extending the Growing Season,”http://www.ext.colostate.edu/mg/gardennotes/722.html

White Oak — A Majestic Native Species

Selecting a shade tree is one of the most important landscaping decisions a homeowner can make.  Unlike perennials or shrubs, which may be easily removed if they don’t work out, a tree is permanent. Because of the prominent role trees play in the landscape, much care and consideration should be given to the selection process.  Of all the shade tree species available to choose from, the oak is the most beloved and treasured in America.  About 400 species belong to the genus Quercus (ancient Latin for oak).  All oaks are long lived and have the potential to become magnificent specimens if given ample space in the landscape.

If you only have space for one large shade tree, an excellent choice is the white oak, or Quercus alba.  In his book, A Natural History of Trees of Eastern and Central North America, 20th century naturalist and tree authority Donald C. Peattie wrote:  “If Oak is the king of trees, as tradition has it, then the White Oak, throughout its range, is the king of kings…no other tree in our sylva has so great a spread.”  Dr. Michael Dirr, renowned horticulturist and woody plant expert, expressed a similar sentiment in Dirr’s Hardy Trees and Shrubs, referring to the white oak as the “standard by which all other oaks are measured.”

Stately White Oak Tree

Stately White Oak Tree

White oaks typically grow 80 to 100 feet or more at maturity.  Specimens grown in a forest setting generally attain greater heights than ones grown in a field or spacious lawn.   Given ample space in which to spread, the branches extend parallel to the ground resulting in a massive canopy as wide as the tree is tall.   This beautiful tree may be found providing shade in parks and suburban neighborhoods, standing as lone specimens in pastures, or grouped in natural stands throughout the eastern part of the United States and southeastern Canada.

MAJESTIC WHITE OAK SPECIMENS IN VIRGINIA

On average, white oaks may live 200 to 300 years but older specimens do exist and have been well documented. In fact, white oaks are said to be able to live 600 years.  In Nancy Ross Hugo’s book Seeing Trees, she describes the life of a white oak as 200 years growing, 200 years living, and 200 years dying.

The largest white oak in Virginia is located at a private residence in Warfield, Virginia (in Brunswick County, which borders on North Carolina).  At 86 feet tall with a 120-foot crown, it is believed to be 500 years old. In 2002, it succeeded the 460-year old Wye Oak in Talbot County, Maryland as the biggest white oak in the nation. Felled by a severe thunderstorm, the national champion Wye Oak was 96 feet tall with a 119-foot crown at the time of its demise.  Just imagine – both trees were more than 200 years old when the Declaration of Independence was signed.

Albemarle County claims the distinction of having the second largest white oak tree in Virginia. It is on property belonging to the Charlottesville Albemarle Airport.

Earlysville White Oak Tree

Earlysville White Oak Tree

Known locally as the Earlysville White Oak, this historic tree is 75 feet tall with an 85-foot crown and is believed to be between 250 and 300 years old. It is included in Virginia Tech’s Virginia Big Tree database and the Remarkable Trees of Virginia Program.

Another ancient white oak in Albemarle County is located on the grounds of historic Emmanuel Episcopal Church in Greenwood, near Crozet.  Estimated to be about 400 years old, this enormous tree is wider than it is tall.  The trunk measures nearly six feet in diameter. The tree is visible to the traffic on U.S. Route 250.  However, it is one of a number of large trees on the property.   So, if you don’t know it’s there, it’s easy to drive by and miss seeing this remarkable white oak specimen.

Ancient White Oak Tree at Emmanuel Episcopal Church in Greenwood, Virginia

Ancient White Oak Tree at Emmanuel Episcopal Church in Greenwood, Virginia

CHARACTERISTICS OF WHITE OAKS  

With the exception of poorly drained or very dry and shallow soil, white oaks are adaptable to most soils but thrive best in deep, moist, well-drained, slightly acidic soil with medium fertility.  The tree develops a long tap root initially, which makes it difficult to transplant successfully.  It is best transplanted as a very young seedling tree or, better yet, grown from an acorn.  Because of its deep root system, it is fairly drought tolerant once it becomes well established.  White oaks grow very slowly when young but start to grow at a faster rate once the roots begin to spread.  A happy, well-planted oak tree can make a prominent presence in the landscape after 15 years or so.

  • FOLIAGE — The leaves generally measure between five and nine inches long and three to four inches wide.
    Rounded Lobes of White Oak Foliage

    Rounded Lobes of White Oak Foliage

    They occur in an alternating pattern along the twig.  Each leaf is wedge shaped at the base and is arranged in five to nine rounded, finger-like lobes.  The dense foliage is dark green to bluish green on top and pale or whitish-green underneath.  While not noted for their fall color, white oak leaves turn deep red to purplish brown.  As winter approaches, the colors become uniformly brown and many of the leaves hang on the tree until spring.

  • FLOWERS – White oaks are self-fertile, meaning both male and female flowers grow on the same tree.  The tiny male flowers appear first and are easily spotted on dangling, two to four-inch long tassel-like catkins.  The female flowers appear later and develop in clusters of two or three bulbous-looking orbs in the axils of new leaves.  Until they mature and begin to take on the initial acorn shape and characteristics, female flowers are very difficult to see because of the tree’s emerging foliage. Pollination is very sensitive to temperatures and, as a result, acorn crops vary from year to year.
  • ACORNS — White oaks don’t start producing large quantities of acorns until the tree is about 50 years old.
    White Oak Tree Acorns

    White Oak Tree Acorns

    Trees located in full sun produce more acorns than those that are shaded by other trees. White oak acorns are a preferred food for a variety of animals, including beavers, white-tailed deer, rabbits, meadow voles, wild turkeys, chipmunks, raccoons, white-footed mice, gray squirrels, crows, blue jays, mallard ducks, wood ducks, white-breasted nuthatches, and bobwhites.

  • BARK – The bark on mature white oak trees is whitish or light ashy gray in color and appears as small, overlapping scaly plates. On older specimens, the bark may be furrowed with rectangular blocks.
  • PESTS – White oaks are subject to attacks by leaf eaters such as gypsy moths, oak leaf caterpillars, and gall-forming insects.   Galls, which are abnormal growths on leaves and twigs, develop in response to several species of gall wasps. They provide both food and shelter to the wasp larvae.  While the galls are unattractive, they don’t actually harm the tree.  In general, none of these pests pose any serious threat to the tree.
  • DISEASES – White oaks may be susceptible to canker-forming bark diseases, root rot, oak blister, and irregular brown areas on leaves and shoots.   However, Virginia Cooperative Extension Publication 426-610 gives the tree an excellent rating with regard to freedom from disease problems.
  • GERMINATION – White oak acorns germinate as soon as they fall from the tree.  However, several factors hinder the rate of germination.  For example, the sweet, nutritious acorns are a favorite food of many animals and are quickly eaten as soon as they fall from the tree.  In years of light acorn crops, the nuts are quickly consumed by animals or destroyed by insects, leaving no acorns available to germinate.  The chances of germination increase only during years of heavy nut production.
  • USES — During the early history of this country, wood from white oak trees was a vital commodity.   Strong, heavy, fine-grained, and durable, the wood was not prone to splintering if broken by impact. Unlike red or black oak species, white oak heartwood has microscopic, bubble-like obstructions called tyloses, which block the pores and make the wood water and rot resistant.  These characteristics made the wood a fine choice for wine and whiskey barrels as well as for shipbuilding. Today, white oak wood is used for lumber, firewood, furniture, paneling, flooring, fence posts, mine timbers, caskets, shingles, barrels, and railroad ties.

ARGUMENTS FOR PLANTING A WHITE OAK IN THE LANDSCAPE

So, in this age of instant gratification, why plant a tree that’s not going to mature in your lifetime?  Think of it this way:  The tree you plant today will be a gift to your children and your children’s children – a living legacy for the generations that follow you.  Think of it as an investment that will, in time, increase the value of your property.  Think of it as a way to support wild life species in a truly significant way.  In his book, Bringing Nature Home, author Doug Tallamy, Professor of Entomology at the University of Delaware, informs us that oak trees are responsible for supporting 534 species of Lepidoptera (moths and butterflies), far more than any other native tree or plant.  While birds and other animals are dependent on the insects that feed on oak leaves, the acorns provide an important food source to a broad range of animal species.

If those arguments don’t convince you to plant a white oak, perhaps this one will.   Oak trees in general are in decline as the result of land development, invasive species, climate change, extensive deer browsing, and many other factors.  Planting a tree that is native to the area will benefit the environment and promote biodiversity more so than any shrub, perennial, or annual could ever do.

If you have ample space to accommodate a large tree and are inspired to plant a white oak, give considerable thought to its placement in the landscape.  This is not a tree that should be planted in a tiny yard or under a power line.  A fully mature white oak specimen requires a great deal of space, perhaps as much as a quarter to half acre for the really ancient ones.  Before planting a white oak, imagine what the tree will look like in 100 or more years. Imagine the amount of shade it will provide.  Imagine the wildlife it will support and the impact it will have on the natural world around it.  Imagine how beautiful that tree will become and how inspiring it will be to passersby and generations to come.  Just imagine….

“The tree which moves some to tears of joy is in the eyes of others only a green thing that stands in the way. Some see nature all ridicule and deformity… and some scarce see nature at all. But to the eyes of the man of imagination, nature is imagination itself.”  William Blake

 

SOURCES

A Natural History of Trees of Eastern and Central North America (Peattie, Donald Culross, 1948).

Dirr’s Hardy Trees and Shrubs, an Illustrated Encyclopedia (Dirr, Dr. Michael A. 1997).

Remarkable Trees of Virginia (Hugo, Nancy Ross and Kirwan, Jeff, 2008)

Seeing Trees, (Hugo, Nancy Ross, 2011)

Albemarle County Native Plants Database Website (www.albemarle.org/NativePlants/)

“Bringing Nature Home” Website (This website supports the lecture series and book Bringing Nature Home by University of Delaware Professor Doug Tallamy) (www.bringingnaturehome.net/what-to-plant)

“Facts about the Earlysville Oak and Other Big Trees in Virginia,” Daily Progress Newspaper Article dated March 30, 2013 (facts-about-the-earlysville-oak)

”Forests of Virginia:  Importance, Composition, Ecology, Threats, and Management,” Virginia Master Naturalist Publication 465-315 (pubs.ext.vt.edu/465/465-315)

Remarkable Trees of Virginia Program website (treesvirginia.org/outreach/remarkable-big-tree-programs)

“Selecting Landscape Plants: Shade Trees,” Virginia Cooperative Extension Publication 426-610, (pubs.ext.vt.edu/426/426-610)

U.S. Department of Agriculture Natural Resources Conservation Service Website (www.nrcs.usda.gov)

Virginia Department of Forestry Website (www.dof.virginia.gov/tree/)

Virginia Tech Department of Forest Resources and Environmental Conservation Website (dendro.cnre.vt.edu/dendrology)

 

The Ornamental Garden in October

In October, the ornamental garden offers up a riot of color that is unrivaled by any other season.  Most fall-blooming species are at their peak this month.  Autumn foliage adds saturated shades of red, gold, purple, and orange to the mix.  As if that weren’t glorious enough, in late afternoon, the shifting angle of the sun lends a golden veneer to the entire landscape.

Chrysanthemum 'Cambodian Queen' Backlit by late October Sunlight

Chrysanthemum ‘Cambodian Queen’ Backlit by late October Sunlight

WHAT’S IN BLOOM IN OCTOBER?

October has a broad palette of plants to choose from – abelia, agastache, globe amaranth, lantana, roses, sedum, salvia, zinnias, and grasses, just to name a few.   The real stars of the show are tried and true fall-blooming plants such as:

  • Aster – Regardless of which species you grow (New England, New York, aromatic, smooth, wood, etc.), asters provide masses of blooms and gorgeous color in the sunny border.  One of the best of the bunch is ‘Raydon’s Favorite’ (Symphyotrichum oblongifolium), a marvelous lavender-blue selection recognized by The Garden Club of America as its 2016 Plant of the Year.
  • Hydrangea – Many hydrangea species and hybrids provide multiple seasons of color.  For example, ‘Limelight’ (Hydrangea paniculata) blossoms gradually fade from pale greenish white in summer to a luscious shade of deep pink in autumn.  ‘Endless Summer’ (Hydrangea macrophylla) turns from either pink or blue to a deep rose, arguably prettier than the summer colors.
  • Tall Sedum 
    Sedum 'Autumn Joy' flanked by Buxus 'Green Velvet' and Euphorbia 'Ascot Rainbow'

    Sedum ‘Autumn Joy’ flanked by Buxus ‘Green Velvet’ and Euphorbia ‘Ascot Rainbow’

    From the moment the foliage emerges in spring until frost covers its seed heads in winter, this hardy, drought-tolerant plant looks great all year round.  Depending on the selection, fall blossoms range in color from soft pink to deep brick red.  ‘Autumn Joy’ is the best known of the tall sedums, but ‘Autumn Fire’, ‘Matrona’, and ‘Neon’ are other selections that are easy to find.

  • Chrysanthemum – Hardy garden mums provide a looser, less formal look than the tightly formed, spherical cushion mums that flood garden centers in autumn.
    Hardy Chrysanthemum 'Sheffield Pink'

    Hardy Chrysanthemum ‘Sheffield Pink’

    Generally ranging in height from two to three feet, hardy mums bloom non-stop until the first killing frost.  ‘Sheffield’ is a particularly lovely selection with deep salmon pink buds that fade to soft apricot flowers.  ‘Cambodian Queen’ makes a huge impact with masses of clear orchid-pink flowers.

  • Pink Muhly Grass (Muhlenbergia capillaris) – This native plant transforms from a simple clump-forming grass to a billowy haze of deep mauve in autumn.  Spectacular when back-lit by sunlight, muhly grass is easy to grow and undemanding.

GENERAL FALL CLEANUP AND GARDEN MAINTENANCE TASKS 

Most of the chores on your September to-do list still apply in October – weeding, deadheading, transplanting, planting new trees and shrubs, taking cuttings, and more.   Only now, there’s a greater sense of urgency as the weather starts to turn chilly.

  • Continue to tidy up flowerbeds.  Bag and dispose of any diseased plant materials.  Rake dead leaves from beneath rose bushes and other plants that may have developed black spot or other fungal diseases over the summer.  If left to overwinter on decaying leaves, these fungal spores will affect next year’s garden.
  • Shred or chop fallen leaves and compost them or save them to use as mulch on next year’s garden. If you’re new to composting, check out Virginia Cooperative Extension (VCE) Publication 426-703, “Making Compost from Yard Waste” (pubs.ext.vt.edu/426/426-703).
  • Remove cool-season weeds, such as chickweed, dandelion, wild onion, plantain and white clover.  A few minutes spent pulling these weeds from flowerbeds now will save you many hours of work next spring.
  • Have a soil test done this fall if you haven’t had one done in the past two or three years.  Soil amendments, such as lime, manure, compost and chopped leaves, are best added to flower beds in the fall.  But don’t amend until after you get the results of the soil test. For additional information on soil testing, see VCE Publication 452-129, “Soil Sampling for the Home Gardener” (pubs.ext.vt.edu/452/452-129).
  • Hold off on mulching flowerbeds until after the soil freezes.  That may not be until November or December.  Just keep in mind that mulch applied to warm soil in fall can do more harm than good.  The purpose of mulch is not to keep the soil warm but to help keep the soil temperature constant and to help prevent frost heaving.
  • As you perform your fall cleanup chores, look for interesting dried plant materials that you can use for winter arrangements and crafts.  Look for dried milkweed pods, sweet gum seed pods, dried flowers, locust pods, staghorn sumac, various grasses and grains, lichens, and mosses.

ANNUALS AND PERENNIALS

Watch the weather for the first killing frost.  The days are now noticeably shorter, so stay alert to night-time temperatures.

  • If chilly overnight temperatures are predicted, cover fall-flowering perennials such as mums and asters to prevent frost from cutting short the blooming period. Just remember to remove the cover if warm temperatures are expected for the next day.
  • Cut back perennial foliage after a killing frost, leaving some seed heads to provide food for wildlife.  During the winter, when food is scarce, seed-eating birds, such as finches, sparrows, chickadees and nuthatchs, appreciate the seed heads of Echinacea, Rudbeckia, Helianthus, coreopsis, lavender, Russian sage, teasel, thistles, grasses, and grains.
  • If you haven’t gotten around to saving seeds from annuals to use in next year’s garden, do it now.  As a reminder, seeds from hybrids are unlikely to come true.
    Zinnias in Late Fall

    Zinnias in Late Fall

  • Leave seed heads in place for annuals that you want to self-seed or just scatter the mature seeds where you want them yourself.   Some annuals and biennials that reseed themselves include cleome, cockscomb, cosmos, foxglove, hollyhock, larkspur, money plant, sweet William, forget-me-not, Shirley poppy, zinnia, four-o-clock, marigold, vinca, and impatiens.
  • Pull out spent annuals. Compost them if they are disease and pest free or, if not, bag them and put them in the trash if they are not.
  • It’s not too late to plant cool-season annuals such as snapdragons, larkspur, pansies, violas, calendula, Iceland poppies, California poppies, or love-in-a-mist.
  • Divide and transplant spring and summer-blooming perennials early in October. Most perennials, including daylilies, coreopsis, Shasta daisy, lamb’s ears, penstemon, and yarrow, benefit from being divided every three to five years.  If you’re not sure whether a plant needs dividing, step back and take a look at it with a critical eye.  Does the plant splay open or split in the middle?  Does the center of the plant have smaller leaves or fewer flowers?  Does the center of the plant appear to be dead? Does the plant appear to be crowding its neighbor plants?  If the answer to any of these questions is yes, then the plant needs to be divided.  Early fall is an ideal time to divide plants because they will have time to establish new roots over winter and will be better equipped to deal with next summer’s heat and dry weather.
  • Take cuttings to root over the winter.  If you’re not sure how to do this, see VCE Publication 426-002, “Propagation by Cuttings, Layering and Division” (pubs.ext.vt.edu/426/426-002).

TREES AND SHRUBS

Fall is the ideal time to plant trees and shrubs in your landscape.  Think about selecting plants that offer multi-seasonal interest.  Some trees to consider include maple (Acer spp.), ginko, black gum (Nyssa sylvatica), dogwood (Cornus), or sourwood (Oxydendrum arboretum).   Some suggested shrubs for multi-seasonal interest include Virginia sweetspire (Itea virginica), oakleaf hydrangea (Hydrangea quercifolia), fothergilla (Fothergilla gardenii), blueberry (vaccinium spp.), red-twig dogwood (Cornus spp.), or spicebush (lindera benzoin).

  • Take preemptive action to prevent deer damage to the bark or branches of young or newly planted trees and shrubs. In fall and winter, male deer rub or scrape against young trees for two reasons: (1) to rub the summer velvet from their horns and (2) to mark their territory as a way to attract female deer and warn other male deer away. Wrap vulnerable tree trunks with a physical barrier such as wire or plastic mesh tree guards, chicken wire, or woven wire fencing.  This will protect the trees while allowing them room to grow.
  • Water newly planted trees and shrubs until the ground freezes. This is critical to the survival of the plants over the winter months.
  • Inspect your evergreen trees and shrubs for bagworms.  Bagworm eggs overwinter on evergreens such as junipers, spruce, hemlock, and arborvitae as well as many other trees.  Pick off and burn any egg cases that you find.  See VCE Publication ENTO-83NP, “Bagworm” (pubs.ext.vt.edu/2808/2808-1008).
    Bagworm

    Bagworm

  • While conifers such as spruces, firs, and pines routinely shed their oldest needles in fall, yellowing needles on this year’s growth may indicate drought stress or possibly disease or insect damage.  If concerned about the health of the tree, contact the Virginia Cooperative Extension helpdesk (434-872-4583 or albemarlevcehelpdesk@vt.edu) for advice.

BULBS

  • Divide and transplant Asiatic and oriental lilies early in the month.   If not divided every two or three years, they lose their vigor and either stop blooming or produce smaller flowers.
    Asiatic Lily 'Peau Douce'

    Asiatic Lily ‘Peau Douce’

    Carefully dig about one foot down and several inches out from the plants so that you don’t damage the bulbs with your spade.  Lift the bulbs from the soil and gently separate the attached bulblets from each “mother” bulb.  Do not let the bulbs dry out.  Replant them immediately in groups of three or more spaced about 8 to 10 inches apart.  Plant the original bulbs about five or six inches deep and the bulblets about three or four inches deep.

  • Dig up tender bulbs, such as caladiums and dahlias, after the first frost blackens the foliage.  Allow them to dry off and gently brush any loose dirt and debris from them.  Store in a cool, frost-free location over the winter months.
  • Plant spring-blooming bulbs, now that soil temperatures are dropping into the 60s or below.  Plant a selection of bulbs for a succession of color next year starting with the earliest snowdrops and ending with the latest blooming tulips.  As you plant bulbs, loosen the soil with a trowel or a bulb planter and place the bulb with the root side down.  If you’re not sure which is the root side versus the blooming end, just plant the bulb on its side.  The bulb will figure it out for you.
  • As a precaution, wear gloves when handling bulbs or wash your hands with cool water and soap immediately after planting.  Some people have a reaction similar to contact dermatitis when handling tulip, daffodil or hyacinth bulbs.   For people who are susceptible, the bulbs may irritate the skin causing a rash, itching, inflammation, and blisters.

HOUSEPLANTS

Now that houseplants have been moved back indoors, pay attention to their needs so that they stay healthy and look their best over the winter months.

  • The best way to kill a houseplant is to overwater it.  To avoid this, allow potting soil to dry between waterings.  As the days grow shorter and light intensity is reduced, houseplants need less water.
  • Another mistake is to plant a houseplant in a pot that doesn’t have a drainage hole.  Water collects in the bottom of the pot and can cause roots to rot.   Always check houseplants to make sure water drains away from the roots.
  • Water houseplants with room-temperature water.  Tropical plants in particular do not like water below 65°F.  Cold water may reduce leaf size, cause leaf drop, and may possibly kill the plant.  Warmer water actually stimulates growth.

If you have an amaryllis, Christmas cactus, kalanchoe, or poinsettia, start conditioning it now for re-bloom during the winter holidays. These are photoperiodic plants, which means they react in a certain way to the daily cycles of daylight and darkness.  By manipulating the amount of light they receive, you can control their bloom schedule.

  • Amaryllis (Hippeastrum) bulbs will re-bloom provided they go through a period of dormancy first.  If you had an amaryllis bulb outside over the summer, bring it indoors by the first week of October.amaryllis Amaryllis prefers to be pot bound, so leave it in its pot or, if the plant was growing in the ground, re-pot it in a pot that is just slightly larger than the bulb. Cut off any dead leaves at the top of the bulb but leave any live leaves alone.  Place the potted plant in a dark, dry place for six to eight weeks. Do not water the bulb until the end of the dormant period.  Once new growth appears, begin to water the bulb on a regular schedule.
  • Christmas Cactus (Schlumbergera bridgesii) is one of the most popular houseplants over the holidays. If you have one and want it to re-bloom by the holidays, start conditioning it eight weeks in advance.
    Christmas Cactus

    Christmas Cactus

    To set flower buds, they need 13 hours per day of uninterrupted total darkness at temperatures between 55 and 70°F.  If you’re not able to provide overnight temperatures that cool, give the plant 15 hours of darkness at temperatures above 70 degrees.  When the flower buds appear, increase the amount of water you give the plant but don’t overwater. Too much water may cause the buds to drop off.

  • Kalanchoe (Kalanchoe blossfeldiana) should be kept in the dark for 13 hours per day for 30 days.  After that, it should start to show flower buds.   At that point, return the plant to normal periods of light and dark.
    Kalanchoe

    Kalanchoe

    If this is too much trouble, the plant will bloom next spring under normal growing conditions.  Should the plant become leggy and less vigorous-looking after it finishes blooming, cut it back and feed it with a water-soluble liquid fertilizer.  Putting it outside next summer and giving it some sunlight will restore it to a robust, sturdy-looking plant.

  • Poinsettias (Euphorbia pulcherrima) begin to develop flower buds in October in response to shorter days.  However, to get the plant to re-bloom successfully, place it in a room or closet where night temperatures are around 60°F and protect it from artificial light at night for a minimum of 12 hours of darkness.  Return it to a sunny window during the day.  Start the darkness treatment about 11 weeks before Christmas and continue through the end of November, at which point the plant may be placed in a warm (60°F or warmer), sunny window.  Provide adequate water and fertilizer throughout this time so that the plant produces a healthy display of color for the holidays.
    Poinsettia in Bloom

    Poinsettia in Bloom

 

 

 

 

 

 

Interpreting Your Soil Test Report

Slide2

Photo Source: Washington State University

I remember it just like it happened yesterday —  though more years have passed than I care to admit.  It was the day I carried an apple leaf sample into our local extension office to diagnose a problem of discolored leaves. As I presented the sample to the extension agent, I began to describe the curled brown edges of the leaves.  Looking back now, I realize that the extension agent must have had a lot of patience because I’m sure she could see the sick leaves as well as I could!   She looked up from her microscope and let out a long, drawn-out “Hmmm.” I began to explain that I had been very vigilant, spraying every ten days, even after rains.  I had even brought in the container of multipurpose fruit spray that I had been using for her to examine, thinking the only possible reason for the yellowing leaves had to be that the spray wasn’t doing its job.

“Well . . . ” she responded, “when was the last time you did a soil test?” I avoided the question and responded, “ I feed my apple trees twice a year, in the fall and  spring with a complete fertilizer, and I don’t think fertilizer is the problem.” She must have had an anger management class somewhere in her past because she just smiled and said, “Many times the symptoms of trouble in plants are caused by nutrient deficiencies.  Quite possibly, this is the most-overlooked of all causes.  There is an interrelationship between a nutrient’s availability and the soil pH, air and soil temperature, available water, and amount of soil organic matter.   A soil test is the best starting point in diagnosing the problem you’re having with your apple trees.” She reached into the cabinet behind her desk and pulled out a soil sampling kit and handed it to me. She proceeded to go over the instructions included in the soil test kit on how to take a proper soil sample, how to prepare the samples for testing, and how to send the samples to  the soil lab at Virginia Tech.

Well, I went home and collected some soil from around the apple trees.  The instructions were pretty easy to follow.  About 15 days after I  mailed the sample, an email appeared in my inbox with the soil test results.  Well, it might as well been written in Greek or Chinese.  It was a bunch of numbers. I began scratching my head, and for a moment considered simply fertilizing again, but I couldn’t help noticing that the report made no mention of adding fertilizer.  So I figured I needed some help.  I printed out a copy of the soil test results and headed to the extension office.

 

                                                                   Apple tree soil test results

The extension agent took a quick look at my test results, drew some red circles and a line and asked if I had followed the recommendation.   Naturally, I said, “What’s lime got to do with the my apple leaf problem?” At that point I thought I detected a slight roll of the eyes, but the agent proceeded to translate the report for me.

As the agent patiently explained, a soil test provides an estimate of the level of available nutrients in the soil. The soil test measures the available levels of the following nutrients: phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), zinc (Zn), manganese (Mn), copper (Cu) and boron (B). The units of measure are given in either pounds per acre, or parts per million.

Slide1

Leibig’s Barrel Analogy —  A barrel with broken staves at different lengths will only hold water up to the shortest stave. Adding phosphorus (P) will not help if the deficiency is potassium (K). Source:Research Center for Chemical Risk.

 

Okay, I’m thinking, what’s the big deal, but before I could get a word in, she began to talk about some German dude named Liebig from back in the 1800s and his “Law of the Minimum” which states, “Plants are generally limited by only one single physical factor that is in the shortest supply relative to demand.” The extension agent went on to explain that this principle simply means that a plant’s health and growth could be adversely affected if only one nutrient is deficient. What’s that old saying? A chain is only as strong as its weakest link. So that’s why it’s important to pay attention to all the nutrient levels on the report.

Turns out there are three Primary Macronutrients: Nitrogen (N), Phosphorus (P) and Potassium (K).

 

Nitrogen

Nitrogen, more than any element, promotes rapid growth and dark green color. In general, plants require more nitrogen than any other mineral element as an essential part of protein and chlorophyll.

Although nitrogen is the most important of all nutrients, you will not find a measurement of this element in your soil test results from Virginia Tech’s Soil Test Lab — and that’s the case for most soil testing labs. Why?  Nitrogen is the most mobile nutrient in the soil, and as a result, soil tests for nitrogen are not reliable for predicting nitrogen fertilizer needs in many situations. Nitrogen fertilizer recommendations are based on the kinds of plants/crops being grown. It is assumed that there is no nitrogen in the soil, that the plants used most of the nitrogen in the previous year, and that what was left over was leached out by rainfall or evaporated as ammonia. However, if the soil has a high percentage of organic material, there may indeed be nitrogen in the soil, depending on the type of organic matter. However, the assumption of the lab is that nitrogen needs to be replaced each growing season. The nitrogen recommendation is made specifically for the plants or crops you plan to grow.

Shown below is a recent soil test performed on a rose garden; note the nitrogen recommendation (Note 225).

Slide4

If you look at the “Lab Test Results” section, you will see that all the nutrients, except nitrogen, are listed from left to right, and beneath each nutrient is the “Result” — simply the amount of that nutrient found in your soil.  The first four nutrients measured are phosphorus (P), potassium (K), followed by two secondary nutrients: calcium (Ca) and magnesium (Mg)  The report indicates the available amount of these four nutrients in pounds per acre. The micronutrients zinc (Zn), manganese (Mn), copper (Cu), iron (Fe), and boron (B) are reported in parts per million.

But back to the results from the soil under my apple trees.  I was getting a little dizzy looking at all those numbers, P =51 lb/A, K=160 lb/A, Ca=1088 lb/A,  and Mg=152/A.  It was beginning to look like a bunch of gibberish. So I lied, and said, “Okay, piece of cake.”  I couldn’t wait to see what valuable piece of information would be revealed in the next line, which was labeled “Rating” and which contained a bunch of letters and plus and minus signs.

Well all of a sudden the light bulb came on when the extension agent began to explain the letters.  Turns out we don’t need to understand the numbers, so long as we understand the letters, ranging from VH, H, H-, M+, M, M-, L+, L,  to L-, which tell us just how bad or how good those results are.  I was actually right when I guessed that VH=Very High levels, H=High levels, M=Medium levels, and  and L=Low levels.  So the number 51 under P might not mean much to me, but I could easily see from the H- rating that I had relatively high levels of phosphorus in my soil.

The extension agent explained that “The Ratings” are derived from the test numbers. In general, when a nutrient has a low rating, plants almost always respond well to fertilizer. When a nutrient is rated M for Medium,  a moderate amount of fertilizer  is typically recommended to maintain fertility. When a nutrient is rated High or Very High, plants usually don’t respond to fertilizer and no fertilizer recommendation is made.

 

Slide3

Soil Test Ranting VS Probability of Crop Yield Response to Nutrient addition. Crop Yield will increase due to nutrient addition at low rated tested values and unlikely at high rated soil tested values. Source: Oregon State University, Publication EC 1478.

 

As an example, the agent pulled out a calibration chart on phosphorus to show how my test results (numbers) were translated to a rating.  The lab result for the level of phosphorus was 51 lbs per acre; therefore, it fell into the H- (Low High) rating.

Phosp ranting

Chart Source: Phosphorus Soil Test Calibration, Virginia Cooperative Extension, Publication “Guide to Soil Recommendations of Virginia

Continuing on with the soil test results: the micronutrients zinc (Z), manganese (Mn), copper (Cu), iron (Fe) and boron (B) test results are reported in parts per million, but don’t worry too much about these numbers either. The rating is our main focus. The micronutrients are rated a little differently; here the test results are rated with a simple Suff. (sufficient) or Def. (deficient). Only those micronutrients rated Def. will require corrective action. The soil test lab will make a recommendation for the material and quantity if needed.

Now I was getting a little frustrated; all the test results were either rated in the high range or sufficient, with the possible exception of calcium (Ca) which tested in the Medium range.  Maybe I needed to tweak the calcium level to get it into the high range?  So I popped the question, “What’s a good source of calcium and why wasn’t there a recommendation made to add calcium?” I was told to hold that thought until we finished going over the soil test.

The next item we discussed was pH, and the result for this element was 5.2. Now my jaw dropped when I was told that one of the most important  — if not the MOST important — soil factors that affects a plant’s growth and health is the pH level of the soil. The soil pH test measures how acidic or basic (alkaline)  the soil is. The pH scale is a logarithmic scale and ranges from 0-14; a pH level of 7 is neutral. A pH less than 7 is acidic and a pH greater than 7 is basic. Since the pH scale is logarithmic, a soil with a pH of 5.7 is 10 times more acidic than a soil with a pH of 6.7, and a soil testing 4.7 is 100 times (10 X 10) more acidic than a soil testing 6.7. The same principle holds true for soils testing above 7.0 — each whole number is 10 times more alkaline or basic than the next whole number. This explanation may be confusing for those of us who are “math challenged,” but the main thing to remember is that when the pH needle moves one whole point, it’s not just one point, it’s 10 times that because the pH scale is logarithmic. (Plaster)

Why is pH so important?  The degree of acidity or alkalinity of the soil is directly related to the availability and uptake of soil nutrients to plants. At pH extremes, some nutrients become partially or completely locked up in the soil and become unavailable to plants. In short, the pH factor is the keeper of the nutrient key. Adding amendments or fertilizer to soils with extreme pH levels will have little or no effect on plant growth.  Correcting the pH level opens the nutrient door and allows the  amendments and fertilizers to be used effectively.

 

Slide1

As we can see in the chart above, the thicker the bar, the more available the nutrient. A pH above 6.2 will insure that all nutrients are available to my apple trees. But the soil around my apple trees had a pH of 5.2, which meant that my soil was more than 10 times too acidic.  My apple trees were having a hard time pulling the needed nutrients out of the soil.  The Soil Lab at Virginia Tech will recommend adding lime to soils with a pH of  less than 6.2 , since the pH of the soil for growing apples should be in the range of 6.2-6.5   Thus, the brown edges on my apple leaves could be the result of a nutrient deficiency, not because the soil lacks a particular nutrient(s), but because the nutrient or nutrients have become unavailable due to the low pH of the soil. Who would have thought acidic soil could be the problem?

Okay, now I see that adding lime is essential.  And it turns out one of the major elements in lime is calcium (in the form of CACO3), meaning that when I add lime to raise the pH of the soil, I will also be adding calcium. There is a lime product called Dolomite Lime ( Ca,Mg)CO3 that contains not only calcium but magnesium, and it may be used if the soil tests low for magnesium. (Brady)

The next block on the test result form is the Buffer Index.  The Buffer Index is used by the lab to determine how much lime is needed to change the pH of the soil.  Any time the soil pH is below 7.0, there will be a buffer number of 6.60 or lower, depending on both the pH and the type of soil (sandy or clay). The lower the buffer number, the more difficult it is to change the pH of the soil. In the case of soil around my apple trees, with a very low pH of 5.2 and a low buffer number of 5.89, a lot of lime will be needed. Fortunately, the folks in the lab do the calculations and make a recommendation on the correct amount needed.  Because the lab does all the work for us, we can disregard this measurement.

The next number is Est.-CEC (Estimated Cation Exchange Capacity).  This is a measurement  of how well the soil holds water and nutrients or how “sticky” the soil is to some nutrients. A more exact scientific definition is the measurement of the total exchangeable cations (positively charged ions) a soil can adsorb. Nutrient cations in the soil include calcium, magnesium, potassium and hydrogen. In general, the greater the amount of clay and organic matter in the soil, the higher the number. Clay particles are smaller than sand particles, therefore, clay has more surface area to attract positively-charged ions.

Okay, what does this mean? Simply, think of a fuel tank; the larger the fuel tank (higher CEC number), the greater the soil’s capacity to hang on to nutrients. As plants remove nutrients (cations) from the soil , the fuel tank replenishes the soil with nutrients which are then available to the plants.

Sandy soils (larger particles=less surface area) generally have a low CEC number (smaller fuel tank) which means that nutrients (fertilizer) need to be added more often. Clay soils (small particles= greater surface area) have a high CEC number (larger fuel tank) which means that nutrients need to be added less often. The pH of sandy soils also needs to be adjusted more frequently because water passes through sandy soils at a rate greater than through clay soils which have a higher water-holding capacity. As water passes through the soil, basic nutrients such as calcium and magnesium are flushed or leached out. They are replaced by acidic elements such an aluminum and iron, and over time, the pH of the soil becomes more acidic (lower pH). Also, the application of certain fertilizers such as ammonium or urea speeds up the rate at which acidity develops.

Slide2

As a general rule, the lower the CEC number, the more fickle 0r volatile the pH of the soil, requiring more frequent applications of lime and more rigid pH monitoring.  In general, the pH in sandy soils with a low CEC value are less stable and change at a faster rate than clay soils. The higher the CEC number the more stable the pH, adding organic matter to the soil generally increases the CEC value of a soil.

The next block on the soil test form; “The Percent Acidity”  is a ratio derived from the Buffer Index. The higher the percentage, the higher the amount of reserve acidity in the soil. This number will rise and fall in relationship to the of the soil’s pH. In general, the home gardener can just ignore this measure, since it is used by the lab to calculate the amount of lime required to adjust the pH to the desired level.   The term  “N/A” will be entered into the block if the pH is 7.0 or above.

The  “Percent Base Saturation”  is the percentage of cation sites filled with exchange bases (Ca, Mg and K).  Huh??  Unless you are a soil scientist, this number can be disregarded!   But if you’re curious enough to want a detailed explanation, I can safely say that it is an expression of the soil’s “potential fertility.” (Plaster).

And if you want to know where the Percent Base Saturation number came from, take a look at the rose garden test results again. Calcium occupies 78.5% of the cation sites, followed by Mg with an occupation rate of 12.1 %, followed by K with a percentage of 1.7%. Doing the math, you add these numbers up:   78.5%+12.1%+1.75%=92.2%, which just happens to equal the Percent Base Saturation rate of 92.4% on the rose garden test results.

Since base saturation is simply an indirect expression of soil pH, base saturation is generally not used for making fertilizer or lime recommendations. In acidic soils, base saturation and soil pH change simultaneously. Liming increases base saturation and soil pH. Sulfur application will reduce base saturation and pH. Base saturation is not a useful concept in alkaline soils, where base saturation equals or exceeds 100 percent.

The  “Percent Ca, Mag and K Saturation”  refers to the relative number of CEC sites that are occupied by that particular nutrient and is a way of determining any gross nutrient imbalance.

At one time, many labs provided recommendations to achieve very specific ideal potassium (K), calcium (Ca), and magnesium (Mg) saturation ratios or percentages. This approach was never supported by data. Research at University of Minnesota and Iowa State University suggests that an ideal ratio or percentage does not exist.  Even if the ratio or percentage is considerate optimum, a nutrient deficiency may still exist. A sufficient supply of nutrients in the root zone is the most important consideration in making fertilizer recommendations.

The block labeled Organic Matter (percentage) is an optional measure for an additional $4.00. Now that I know just how organic matter can affect a number of soil fertility components, I think this information is well worth the $4.00.

For an additional fee of $2.00 the lab will proved another  optional measurement, S. Salts (Soluble Salts). I did not request this measurement for my apple orchard soil test, but I did request it on the rose garden soil test. My reason was that the garden in question is a public rose garden, and over the years it has been fertilized very heavily.  In addition, the rose garden is located adjacent to a sidewalk, and I had some concern about run-off from salts used to melt ice and snow on the sidewalk. The test results for S. Salts was 141 parts per million (ppm). Injury to plants may start to occur at soluble salt levels above 844 ppm , especially to seedlings and germinating seeds. Salt damage can be intensified during dry periods. Happily, the soluble salt levels (144 ppm) in the rose garden are well below the level that could cause injury.

If you have concerns about possible toxic elements such as lead or arsenic, you must engage a private laboratory since the soil lab at Virginia Tech does not offer this service.

There were two recommendations on my apple orchard soil test:  to add boron and lime to correct the pH level. Because of the large amount of lime recommended, 3.5 tons per acre, I made 3 applications over a period of 9 months. It takes 2 to 3 years after application for lime to react completely with the soil; however, benefits from the addition of lime may occur within the first few months after application. How long the effects of lime last will depends on the kind of lime used, total soil acidity, amount of organic matter, type and amount of clay, and cropping and management systems used. Because of these multiple factors, a soil test is recommended every 3 to 4 years.

I leaned a lot during that office visit.  Most importantly, I learned that a soil test is one of the best investments a gardener can make. The purpose of a soil test is to provide the gardener with information needed for making a wise investment in fertilizer and soil amendments. Ideally, soil samples should be taken a few months before any new landscaping is planted. Fall to early winter is the perfect time frame to test the soil and to add the recommend nutrients. This timing allows added nutrients to start working in the soil. As I mentioned, the general rule is that a soil test should be taken once every three to four years, but it should also be considered if there is abnormal growth or a change in plant color. And remember, soil samples should NOT be taken within 6 to 8 weeks of fertilizing or liming.

Looking back now, life would have been a lot simpler and my apple trees more productive if I had taken the soil test and followed the recommendations PRIOR to planting the apple trees. A soil test, if taken prior to planting, can be a tool to help you determine what kind of plants to plant. Why not embrace the existing soil condition?  For example, if a soil test indicates a low pH, why not consider planting “acid loving (low pH)” plants such as blueberries, azaleas, rhododendrons, hydrangeas, or  even a dogwood  tree?

With your soil test report in hand, you can stop guessing and add necessary amendments in the right amounts to create a fertile environment for your lawn, your flower bed, your vegetable garden or even your apple orchard.  Conducting a soil test is one of the best and least expensive ways of insuring that your landscape will flourish.

Thanks for joining us in The Garden Shed.  We hope you drop by again next month.

Resources:

“Nutrient Disorders In Fruit Trees,” Washington State University, Publication PNW 121W, http://whatcom.wsu.edu/ag/documents/treefruit/pnw0121e.pdf

“Essential Elements for Plant Growth-Law of the Minimum,” University of Wisconsin, http://soils.wisc.edu/facstaff/barak/soilscience326/lawofmin.htm

“Setting a New Trend,” Research Center for Chemical Risk, https://unit.aist.go.jp/riss/crm/crm_e/directors_address_2003e.htm

“Soil Test Interpretation Guide,” Publication EC1478, Oregon State University, https://catalog.extension.oregonstate.edu/ec1478

Soil Recommendations of Virginia Guidebook, Virginia Cooperative Extension, http://www.soiltest.vt.edu/PDF/recommendation-guidebook.pdf 

“Soil Test Note #1, Explanation of Soil Tests, Virginia Cooperative Extension Publication 552-701, http://pubs.ext.vt.edu/452/452-701/452-701.html

“Fundamentals of Soil Cation Capacity (CEC),”  Purdue University Cooperative Extension Service, Publication AY-238,  https://www.extension.purdue.edu/extmedia/ay/ay-238.html

Plaster, Edward J.,  Soil Science & Management (2009), p. 266.

Brady, Nyle C., The Nature and Properties of Soil (14th ed.), pp. 387-393.

“Facts about Soil and Acidity,”  Michigan State University, https://www.oakgov.com/msu/Documents/publications/e1566_soil_acidity.pdf