The Ornamental Garden in November
November might seem to be a gardening month of all work and no play. But there’s something very rewarding about putting a garden to bed properly and tidily. Fall chores can satisfy a gardener’s nesting instinct: cleaning tools and hanging each in its spot; cleaning and stacking pots; draining and coiling hoses; gathering plant labels to be sorted over in winter. Some big gardening chores, such as planting or transplanting deciduous trees and shrubs, can also be tackled this month. Let’s look at our November list and see what needs to be done before the holiday rush begins.
PLANTING NEW TREES
Planting deciduous trees from September through November allows the roots to become established before the ground freezes and winter sets in. In the fall, cooling temperatures, still-warm soil, and adequate moisture can help trees get a head start on establishing roots. As long as the soil temperature is above 40 degrees, roots will continue to grow. In spring and summer, foliage requires extra moisture which means having to keep newly-planted trees well-watered.
Broadleaf evergreens are best planted in the spring, although some, such as mountain laurel, boxwood, and hollies, can be planted in the early fall if they are given deep watering and a thick acidic mulch.
Note: Individual planting holes should not be amended with compost, manure, peat moss, or other soil additions. This could discourage roots from reaching beyond the hole and getting established in native soil. In addition, water tends to stay in a hole with lighter amended soil; this could suffocate the roots or cause root rot.
For instructions on how to plant container trees, balled-and-burlapped trees, or bare-root trees, see “Planting A New Tree” The Garden Shed, October 2015.
For those who choose to buy live Christmas trees that can be planted after the holidays, pick your planting spot now and dig the hole before the ground freezes.
TRANSPLANTING ESTABLISHED TREES AND SHRUBS
Smaller trees and shrubs can be transplanted when dormant. Larger trees and shrubs, however, require planning and advanced preparation before being uprooted. Tree and shrub roots normally grow well beyond the soil volume that can be moved. To keep most of the roots within a small area, these roots need to be pruned at least six months in advance of transplanting. Ideally, root pruning is done in stages about 1-to-2 years before the plant is transplanted. Begin root pruning by marking a circle the size of the desired root ball around the tree or shrub. Then dig a trench just outside the circle. Refer to pruning recommendations by the American Association of Nurserymen. Plants to be moved in the fall (October or November) should be root pruned in March, and those to be moved in spring (March) should be root pruned in October. Root prune only after leaves have fallen from deciduous plants in fall or before bud break in the spring. If not root pruned, the plant may die from transplant shock because of root loss. For additional information on planting, transplanting, and root pruning see “Planting Process,” University of Maryland Extension.
FERTILIZING DECIDUOUS TREES AND SHRUBS
Late-summer and early-fall fertilization may stimulate new growth that is not winter-hardy, making deciduous trees and shrubs susceptible to winter injury. Trees and shrubs are typically fertilized after they become dormant in late fall/early winter or, in early spring. Mature shade trees do not typically need to be fertilized at all. Pale green, undersized leaves; early leaf drop; reduced growth rates; and twig die-back may indicate a need for fertilization. These symptoms can indicate problems other than nutrient deficiencies, however, and a soil test is recommended to determine if supplemental nutrients are required.
Fertilizer should not be concentrated around the stem or trunk of a tree or shrub, but should be applied over as much of the plant’s root zone as possible. For trees and shrubs, fertilizer should be applied over an area twice as large as the crown spread or drip line. Since most landscape plant roots grow in the top foot of soil, a surface or shallow application is recommended. If water is unavailable, do not fertilize at all because plants will be unable to absorb the nutrients.
NOTE: When turf is fertilized, tree and shrub roots that extend into the turf area absorb some of the fertilizer, and are therefore indirectly fertilized. For further discussion, see the VCE publication, “Fertilizing Landscape Trees and Shrubs.”
For cool-season grasses, the preferred time for applying N fertilizer is August through October. The second best time is late fall, mid October to late November, when cool temperatures have reduced top growth, but root growth is still active. Low rates of N fertilizer (40 to 50 lbs./acre) will “set-up the plant” for winter and encourage healthy early-spring growth. Not only does enhanced root growth aid in the uptake of water and nutrients, carbohydrate buildup in the stem bases promotes winter survival and spring regrowth. Never apply lawn fertilizer to frozen soils.
For warm-season grasses, the preferred period for applying N is mid April through mid August. For overseeded lawns only, a secondary period for applying a fall nitrogen application is mid October to mid November.
For recommendations of appropriate fertilization schedules and application rates, see the VCE publications, “Maintenance Calendar for Cool-Season Turfgrass Lawns in Virginia,” and “Maintenance Calendar for Warm-Season Lawns in Virginia.”
Mulch is often applied in spring, but check on mulch levels in fall as well. Mulching helps prevent soil erosion; insulates the soil; retains water to keep roots moist; and prevents root heaving caused by freezing and thawing temperatures. Mulch boxwoods and broadleaf evergreens before the ground freezes. Mulch deciduous trees and shrubs, and perennial beds after the ground freezes. Apply mulch as far out as the spread of the branches but no more than three inches in thickness. Mulch should never touch the bark of the plant.
PROTECTION FROM ANIMALS
As the weather becomes harsher and natural food sources become scarcer, deer, rodents, rabbits and other animals will look to trees and shrubs as sources of food. Install tree guards, chicken wire, or stake and plastic fencing around young trees and woody shrubs to discouraging foraging and damage from antler rubbing. These photos show examples of protection against damage from deer rutting.
If autumn rains have been insufficient, give plants a deep soaking that will supply water to the entire root system before the ground freezes. This practice is especially important for evergreens.
Small evergreens can be protected by using windbreaks made out of burlap, canvas, or similar materials. Windbreaks will help reduce the force of the wind and shade the plants. They can be created by attaching materials to a frame that is placed around a plant.
Some hardy perennials can be kept in concrete or other freeze-tolerant containers and buried after the ground freezes. Once buried, cover the pot with a layer of mulch to protect the roots which are vulnerable to freezing. Dig holes now before the ground freezes.
When considering which potted plants to keep outdoors over winter, select plants that are cold-hardy to two zones below your local USDA Hardiness Zone. For Zone 7, select plants that are hardy to zone 5.
Or, keep a plant in its container and move into an unheated garage or basement where the plant can get some sunlight. Reduce watering to about once a month or when soil becomes very dry; do not allow the soil to become completely dry.
Because they are made of porous clay, most terracotta pots are at risk of cracking or shattering in freezing temperatures. Glazed pots, which are usually fired at higher temperatures, tend to withstand freezing better than terracotta, but it is still better to store them inside whenever possible. Some gardeners take the extra precaution of wrapping the sides of the container with several layers of bubble wrap (to protect both delicate containers and root systems), and then mulching.
You can also transfer small containers into a cold frame packed with sand or straw. (To create a temporary cold frame, arrange bales of hay to form four walls and top them with an old window, heavy-duty clear plastic, or a plexiglass lid.)
If you have empty concrete, cement, or clay containers that are too large to move, clean them as much as possible and cover them with lids or plastic sheeting to prevent water from collecting inside and freezing.
For more tips on winterizing container plants and outdoor plants, see “Overwintering Potted Plants,” Brooklyn Botanic Garden.
Paperwhite narcissus is a terrific addition to your holiday decorations. Plant the bulbs, pointy side up, in soil or in water. In just a few days, roots will sprout, and in about 4 to 5 weeks beautiful white blooms will emerge. Plant around Thanksgiving for bloom at the holidays.
Amaryllis is another bulb that can be planted in time for holiday bloom. Although it now comes in a variety of colors, red amaryllis is perfect for the holiday season. You can also choose red with white edging, or white with red edging! Choose a 6-8″ pot heavy enough to prevent the plant from tipping over once the large flower is in bloom. Set the bulb in potting mix, pointy-side up, with about 1/3 of the bulb above the soil line. Place in bright, indirect light, and water sparingly until 2″ of growth appears. Then water regularly. It takes 6-8 weeks for the bulb to flower (although some bulbs bloom earlier, some later). See “Amaryllis,” The Garden Shed, November 2015, for information about planting amaryllis both indoors and in the garden.
ADDITIONAL RECOMMENDED READINGS
The Ornamental Garden in November, The Garden Shed, 2015
The Ornamental Garden in November, The Garden Shed, 2016
The Ornamental Garden in November, The Garden Shed, 2017
“Planting a New Tree,” The Garden Shed, http://piedmontmastergardeners.org/article/planting-a-new-tree/
“Planting Process,” University of Maryland Extension, https://extension.umd.edu/hgic/topics/planting-process
“Transplanting Established Trees and Shrubs,” Clemson Cooperative Extension, https://hgic.clemson.edu/factsheet/transplanting-established-trees-shrubs/
“Planting Trees,” VCE, http://pubs.ext.vt.edu/426/426-702/426-702.html
“Fertilizing Landscape Trees and Shrubs,” VCE, http://pubs.ext.vt.edu/430/430-018/430-018.html
“Maintenance Calendar for Cool-Season Turfgrass Lawns in Virginia,” VCE, https://pubs.ext.vt.edu/430/430-523/430-523.html
“Maintenance Calendar for Warm-Season Lawns in Virginia, VCE, https://pubs.ext.vt.edu/430/430-522/430-522.html
“Managing Winter Injury to Trees and Shrubs,” VCE, https://pubs.ext.vt.edu/426/426-500/426-500.html
“Overwintering Potted Plants,” Brooklyn Botanic Garden, https://www.bbg.org/gardening/article/overwintering_potted_plants
“Amaryllis,” The Garden Shed, http://piedmontmastergardeners.org/article/amaryllis/