The Garden Shed
A Community Newsletter published by the Piedmont Master Gardeners
June 2019-Vol.5 No.6
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Table of Contents
In the Ornamental Garden
Keep up summer maintenance or pay the price.
Recipe of the Month
Kohlrabi Tacos, anyone? With a Thyme Margarita?
In the Edible Garden
June tips to keep the vegetable garden healthy and happy.
In the Ornamental Garden
Use native sedges as groundcovers, lawn alternatives, and accent plants.
Last month we talked about choosing containers, preparing your soil and siting your containers. Now it's time to start planting.
Be inspired by a garden tour, go for a hike, learn new skills, combat invasives!
The Sedge Alternative
Sedges are gaining increasing recognition as a native alternative to nonnative groundcovers such as English ivy (Hedera helix), wintercreeper (Euonymus fortunei), and periwinkle (Vinca minor and V. major). These commonly used nonnative groundcovers have escaped their intended confines and become invasive in many natural areas. Sedges are also an excellent substitute for turf as we struggle to maintain a green home landscape without the dependence on fertilizers, herbicides, and extra watering required for lawns. Properly selected native groundcovers (right plant, right place) require the least amount of maintenance because they establish quickly, are long-lived, suppress weeds, and require little mulch once established.
Although this article will concentrate on sedges, let’s first identify the broader categories of “grass-like” plants. We will look at the differences among sedges, rushes, and ornamental grasses. Lastly, we’ll consider liriope, a frequently used nonnative groundcover that could be confused with the above genera.
Even horticulturalists who specialize in grass-like plants point out the difficulties in identifying different species. A distinguishing characteristic is the stem structure. A common rhyme is useful: Sedges have edges; rushes are round; grasses have nodes all the way to the ground.
- Sedge, a grass-like perennial plant with triangular stems and inconspicuous flowers, grows in a variety of habitats (often moist to wet areas) throughout the world. Of the family Cyperaceae, there are over 1500 species of the genus Carex, which from Latin means “cutter” in reference to the sharp leaves and stem edges. Identification of individual species can be very difficult. Seed heads are located at the end of the stem and are wind pollinated. Sedges have fibrous root systems, and some produce rhizomes.
- Rush, a member of Juncaceae family, is an erect, tufted marsh or waterside plant with inconspicuous greenish or brownish flowers resembling a sedge or a grass. A few are annuals, but most are perennials. Rushes are slow-growing and spread by rhizomes. There are two main genera, Juncus (the largest genus) and Luzula (wood rushes). Juncus members have hairless, cylindrical stem-like leaves; Luzulu members have hairy, grass-like leaves. Widely distributed in temperate areas, some rushes are used for matting, chair seats, and baskets.
- Grasses are of the family Poaceae and have hollow cylindrical stems. The stems of sedges and rushes are generally solid. Grass stems also contain swollen nodes or joints; sedges and rushes do not. Grasses can be either annual or perennial. Grasses will tend to grow in two ways — as clumps that get thicker and wider, or as a spreading mass which sends out rhizomes (below ground) or stolons (above ground) to colonize any available ground. Some ornamental grasses, such as Northern Sea Oats, produce viable seed, but many do not. For more information on different types of grasses and their uses in the landscape, see “Ornamental grasses: easy, beautiful and – invasive?”
- Lirope, of the Liliaceae family, is native to China, Taiwan, and Japan. Often called lilyturf, this evergreen ground cover produces showy lavender, purple, pink or white flower spikes in July and August. Clusters of bluish-black, berry-like fruit follow the flowers. Liriope is remarkably tough and can grow in deep shade or full sun, in sandy or clay soils. Although it requires good drainage, it can endure heat, drought and salt spray. There are two major species: big blue lilyturf (Liriope muscari) and creeping lilyturf ( spicata). L. spicata spreads rapidly by underground stems (rhizomes). Both species form mounds of grass-like foliage. Usually the foliage is dark green, but in some varieties it is variegated. There are many different cultivars of liriope.
Sedges thrive in many different sunlight and soil conditions. Some can be grown in deep shade or full sun, on dry slopes or in standing water. Some are more grass-like in appearance while others have wider leaves (to 1”). They can be massed as lush green groundcovers, reducing the need for mulch. Some can be used in place of turf, reducing lawn maintenance. They can be used as specimen plants in ornamental gardens, or in rain gardens. Foliage comes in bright green, lime green, or blue green.
Native Host Plants
Using native plants in landscaping promotes biodiversity which supports plant and wildlife conservation. As noted in the Carex descriptions that follow, various native sedges act as caterpillar hosts plants for moths and butterflies.
Carex flowers are generally subdued spikes in shades of tan or green that appear in spring before dense foliage growth kicks in. Some flowers fade to become attractive tawny seed heads that billow above the foliage. In the following brief descriptions, I have noted only those flowers that seem to be considered “showier,” although even these sedges are generally grown for the foliage, not the flower.
- C. albicans, white-tinged sedge, used frequently because it tolerates part-shade/sun and dry-to-moist soils. This species tolerates dry soil conditions better than most species of Carex. Grows in clumps 15-20” tall with narrow, grass-like, upright-arching, bright green leaf blades. Best grown in groups or massed for foliage effect. Effective as a ground cover; can be used as a turf alternative. Plants spread slowly by rhizomes and will self-seed in optimal growing conditions. Not listed as deer resistant.
- C. cherokeensis, Cherokee sedge, grows in medium-to-wet soils in full sun to part shade. It thrives in moist soils, but also may do well in average garden soils. It forms attractive, slowly-spreading 6-12” tall clumps with fine-textured, narrow, grass-like, deep-green leaves. Wheat-like seed spikes mature in autumn. Mass or group in open woodland gardens, borders, or rock gardens. It is also an effective accent plant for smaller gardens. Deer resistant.
- C. flaccosperma, blue wood sedge, is easily grown in medium-to-wet soils in part-to-full shade. It thrives in moist soils, but also does well in average garden soils and will tolerate some drought. Forms attractive 6-10” tall clumps of fine-textured, narrow, grass-like, glaucous, blue-green leaves (to 3/8” wide). Tolerates deer and heavy shade.
- C. flaccosperma var. glaucodea, blue wood sedge, is more typically found in drier acidic soils of wooded slopes, upland ridges, ravines or wooded valleys along streams.
- C. grayi, gray sedge, grows best in moist fertile soil in full sun, but will tolerate light shade. It thrives at or near water. It grows 2-3’ tall with greenish yellow to brown seed heads that look like spiked clubs. The grass-like leaves, which are up to 1/2″ wide, are semi-evergreen. Deer resistant.
- C. laxiculmis, creeping sedge, is an evergreen sedge that grows in medium-to-wet soils in part-to-full shade. Soils should not be allowed to dry out, and this sedge needs consistent supplemental watering in hot summer. It typically grows in a dense rounded clump to 12” tall with grassy blue-green leaves up to 1/2” wide. Deer resistant.
- C. laxiculmis ‘Hobb’ BUNNY BLUE is a silvery-blue-leaved cultivar that typically grows in a dense rounded clump to 12” tall with grassy leaves to 1/2” wide. Deer resistant.
- C. lurida, sallow sedge, grows best in wet-to-moist soil in full sun to partial shade. Its grass-like leaves grow up to 3′ tall from short stout rhizomes. The seedheads resemble small sweetgum balls but do not grow above the foliage. Although this sedge does not go dormant in summer, it may require supplemental watering if planted in dry areas. Deer resistant.
- C. muskinomensis is commonly called palm sedge because the leaves superficially resemble miniature palm fronds. This dense, clump-forming sedge produces rigid, erect stems to 20″ tall with 8″ long, pointed, grass-like, light green leaves radiating from the stem tops. It is easily grown in average, medium-to-wet soil in full sun to part shade, although it tends to flop in too much shade. It prefers constantly moist, fertile soil, but will grow in shallow water (3-4″ deep). If grown away from water, soil must not be allowed to dry out. Plants slowly naturalize by rhizomes in optimal growing conditions and may also self-seed. Foliage promptly turns yellow after frost. Cut plants to the ground in winter. Deer resistant.
- C. pensylvanica, Pennsylvania sedge, is used as a lawn substitute for dry soils in shady areas. This low sedge grows in a clump to 8″ tall and is typically semi-evergreen in moderately cold winter climates. Soft, delicate, arching leaves to 1/8″ wide form a turf that never needs mowing, or can be mowed 2-3 times a year to 2″ tall. Often found in areas with oak trees, this plant is also known as oak sedge. It spreads by rhizomes and may sometimes self-seed in optimal growing conditions. It is not a low maintenance choice for garden beds because it tends to outgrow other herbaceous plants. It is a caterpillar host plant for skippers. Not listed as deer resistant.
C. plantaginea, seersucker sedge or plantain-leaf sedge, is a petite perennial woodland sedge with 1’ clumps of striking lime-green, somewhat puckered foliage. Its semi-evergreen leaves are broader (1”) than many other sedges, and they emerge from maroon-colored leaf sheaths. This sedge prefers partly shaded, moist, fertile woods but will tolerate dry, shaded sites. Plants slowly colonize from short rhizomes and produce occasional seedlings. When grouped, this sedge makes an effective ground cover or border for woodland trails. It is a caterpillar host plant for skippers. Deer resistant.
- C. stricta, tussock sedge, is easily grown in moist-to-wet soils including standing water in full sun to part shade. It grows well in wet low spots, water margins, and areas that experience some seasonal flooding. It spreads by rhizomes to form large colonies of dense clumps 1-3′ tall. Older leaves turn straw brown as they die, and build up around the base of each clump; newer leaves are yellowish-green. Flora of North America reports that plants grown in sites with seasonal flooding form distinctive large clumps, and plants grown in drier areas tend to spread more by rhizomes. This sedge is a caterpillar host plant for the Appalachian brown butterfly (Satyrodes Appalachia), Mulberry Wing, (Poanes massasoit), and Eyed Brown butterfly (Satyrodes eurydice). Deer resistant.
- C. vulpinoidea, fox sedge, grows well in damp to very wet soils in full sun to partial shade. Narrow grass-like leaf blades grow in clumps up to 3’ in height. The seedheads, which spray out attractively from the center of the clump, resemble a fox’s tail but are short-lived. This sedge may be weedy and spreads rapidly. It is useful for water gardens or for locations that remain moist near streams, springs, or ponds. Deer resistant.
Summary of Sedge Characteristics and Uses
- C. flaccosperma
- C. albicans
- C. pensylvatica
- C. plantaginea
Wet Soil or Rain Gardens:
- C. grayi
- C. laxiculmis
- C. lurida
- C. muskinomensis
- C. stricta
- C. vulpinoidea
- C. albicans
- C. pensylvanica
- C. albicans
- C. flaccosperma var. glaucodea
- C. pensylvanica
- C. plantaginea
Yellow nutsedge, Cyperus esculentus, is a common lawn and garden weed. The leaves are bright green and have a waxy appearance. It grows faster than many lawn grasses so it is often noticed when it outgrows the surrounding grass. The plant is perennial, reproducing by seed and underground tubers. The underground tubers or nutlets can remain dormant in the ground for several years.
Plant Finder, Missouri Botanical Garden, http://www.missouribotanicalgarden.org/plantfinder/plantfindersearch.aspx
“Ornamental Grasses,” https://extension.illinois.edu/grasses/understanding.cfm
“Ornamental Grasses: easy, beautiful and – invasive?” https://piedmontmastergardeners.org/article/ornamental-grasses-easy-beautiful-and-invasive/
“Ornamental Grasses,” https://web.extension.illinois.edu/dmp/palette/090215.html
“Comparison of grass structure with rushes and sedges,” http://www.countrysideinfo.co.uk/grass_id/intro.htm
Liriope, Clemson Cooperative Extension Home and Garden Information Center, https://hgic.clemson.edu/factsheet/liriope/
Landscaping With Native Plants, A Gardener’s Guide for Missouri, Chapter Four, p.11., Missouri Botanical Garden
Carex plantaginea, http://www.newmoonnursery.com/plant/Carex-plantaginea
Caterpillar host plants, Bringing Nature Home, Douglas W. Tallamy.
Caterpillar host plant for Mulberry Wing, https://www.butterfliesandmoths.org/species/Poanes-massasoit
Caterpillar host plant for Eyed Brown, https://www.butterfliesandmoths.org/species/Satyrodes-eurydice
Caterpillar host plants for skippers, The Living Landscape, Rick Darke and Douglas W. Tallamy.
Green Spring Gardens, www.fairfaxcounty.gov/parks/green-spring/gardening
Native Ornamental Grasses and Sedges for Gardens and Meadows in the Washington D.C. area, Green Springs Garden, Fairfax County, VA
Using Native Plants to Attract Butterflies, Moths, Bees, and other Pollinators in the Washington D.C. area, Green Springs Garden, Fairfax County, VA
“Native Sedges for the Home Garden,” Master Gardeners of Northern Virginia, https://mgnv.org/2018/03/08/native-sedges-for-the-home-garden/
The Vegetable Garden in June
I don’t want to jinx anybody, but so far, our weather this spring has been pretty friendly to gardeners. It has been warm, allowing the gamblers among us to get away with putting warm weather vegetables in the ground early, hopefully portending an early first harvest. And the rain has been regular and helpful, not too much, not too little. We are off to a good start.
So at this point, all of us but those awaiting an imminent apocalypse have planted or are planting any and all crops. Frost risk is extremely low and the ground is warm. In my own garden beds, things really started growing in early May and are progressing nicely. June becomes the time to finish first plantings, start weeding and mulching and continue harvesting cool weather vegetables like lettuces, spinach and radishes. The fun has begun.
As garden space gets consumed, use vertical gardening techniques and practices like intercropping and companion planting to get the most out or your available garden real estate.
Remember to rotate crop locations to minimize the buildup of pests and pathogens. A 3-year cycle is commonly recommended.
Thin the seedlings of carrots, beets and other root crops to the recommended spacing to avoid crowding.
Now that the ground has warmed, apply organic mulches such as leaves, straw and clean grass to conserve water, suppress weed germination, and enrich soil as the mulch decomposes.
Repeat plantings of corn, beans, and other summer vegetables as the cool weather crops go to seed, to extend the harvest season.
Monitor soil moisture. As a general rule, vegetables require about an inch of water per week during the growing season. Soaker hoses or drip irrigation make the most efficient use of water during dry spells.
Water in the mornings and minimize splashing water and soil on plants to minimize the risks of mildew and soil-borne disease transmission. For the same reason, remove lower leaves on your tomato plants to minimize inadvertent soil contact.
Asparagus –– stop harvesting when spears become thin.
Growing lettuce under a shade screening material will slow bolting and extend the harvest season. Also, try planting bolt-resistant varieties such as Muir, Sierra and Nevada.
Continue to mound soil up around potato vines to prevent the tubers from being exposed to the sun and turning green. You can also add a layer of straw or leaf mulch to help control weeds.
Some soils in our area are magnesium deficient, especially those where high-calcium lime has been applied rather than lime containing magnesium (dolomite). “Green” your peppers by giving them a magnesium boost with Epsom salts. This will aid fruit production. Dilute one tablespoon of Epsom salts in a quart of water. Spray the solution on leaves, using a clean household spray bottle. You will notice a difference in the color of the leaves in couple of days.
If you’ve saved some leaves and/or yard trimmings from last fall, combine them with grass clippings and kitchen vegetable cuttings to generate compost that you can apply to your beds prior to winter. I find that roughly equal volumes of grass clippings and mulched leaves is about right to achieve a hot compost batch. If it doesn’t get hot, add more grass and kitchen scraps. If it is slimey or gives off an ammonia smell, add leaves, wood chips, sawdust (not pressure treated) or other carbon source. Keep the pile moist but not dripping and turn it to keep it aerated every week or two. A second heap gets regular additions of materials as they become available throughout the year. It decomposes a bit more slowly and less uniformly than the hot pile, but still produces a beautiful product in the end. It’s worth the effort!
Collapsible puppy pens make a simple, inexpensive compost containment system (see photo). Clip the open ends together for containment. Unclip and swing open to turn the pile.
Herbs planted in average soil need no fertilizer. Too much fertilizer may reduce flavor and pungency.
To control earworms on corn plants: apply several drops of mineral oil to the corn silk.
Thin overloaded fruit trees; this will result in larger and better fruit at harvest time.
Renovate the strawberry patch after harvest. Mow the rows, thin out excess plants and apply mulch for weed control.
The best time to harvest most herbs is just before flowering, when the leaves contain the maxium essential oils. Cut herbs early on a sunny day.
Adapted from the Albemarle/Charlottesville VCE Office, “Monthy Horticulture Tip Sheets,” albemarle.ext.vt.edu/hort-tip-sheets/6-14-veg.pdf ; albemarle.ext.vt.eduhort-tip-sheets/6-14-fruit-nuts.pdf; albemarle.ext.vt.eduhort-tip-sheets/6-14-herbs.pdf
“Vertical Gardening Using Trellises, Stakes and Cages,” https://www.pubs.ext.vt.edu/content/dam/pubs_ext_vt_edu/HORT/HORT-189/HORT-189-pdf.pdf
Virginia Cooperative Extension
Thursday, June 6, 1:00 – 4:00 p.m.
Middleburg Agriculture Research and Extension Center
5527 Sullivan Mill Rd Middleburg, VA (map)
This free educational session will discuss water quality, weeds and weed management, fish population management and alternate uses of farm ponds.
For more information, contact Small Farm Outreach Program Agent Michael Carter, Sr. at (804) 481-1163 or email@example.com or call the Small Farm Outreach Program office at (804) 524-3292.
Through The Garden Gate: The Wadley’s Garden
Hosted by Charlottesville Area Tree Stewards
Saturday, June 8, 9:00 a.m. – 12:00 p.m.
4922 Barn Field Road, Keswick
Take this opportunity to tour a local rural garden situated on a 20+ acre horse farm with magnificent views of the Southwest Mountains. Beginning with one existing tree, the garden now contains more than 50 varieties. The many trees are complemented by dwarf conifer beds, boxwoods, a shade garden and perennial plantings that integrate many types of herbaceous, tree, and intersectional hybrid (Itoh) peonies.
For more information, download a pdf of the 2019_TTGG_brochure. Admission is $5.
Garden Basics: Maintaining the Perennial Garden
Presented by Pat Chadwick, Piedmont Master Gardeners
Saturday, June 8, 2:00 – 4:00 p.m.
Trinity Episcopal Church
1118 Preston Avenue, Charlottesville
There is no charge for attendance, but please reserve a place by sending your name to: firstname.lastname@example.org
Blue Ridge PRISM
Partnership for Regional Invasive Species Management
Monday, June 10, 1:00 – 5:00 p.m.
Ivy Creek Natural Area, 1780 Earlysville Rd, Charlottesville
Class fee: $25
Using both classroom and outdoor instruction (weather permitting), this session will cover summer invasive plant identification and present the best practices for each invasive. There will also be an opportunity to identify plants, so bring samples of your mystery plants!
Register at Eventbrite or Facebook.
Virginia Native Plant Society, Jefferson Chapter
Native Plant Walk
Saturday, June 15, 9:00 – 11:00 a.m.
Ivy Creek Natural Area, 1780 Earlysville Rd, Charlottesville
Meet by the kiosk near the parking lot. Free! All are welcome. No registration required.
Saturday, June 15
Saturday, June 22
Saturday, June 29
10:00 a.m. – 12:00 p.m.
Join a Foundation Naturalist for an interpretive hike. Explore Wintergreen’s natural environment! These hikes are rated moderate. Nonmember fee is $8, members free. Meet at the Nature Foundation. Register at: https://www.twnf.org/nature-events/
The Nature Foundation at Wintergreen
Nature Journaling and Sketching Walk Workshop
Saturday, June 22, 1:00-3:00 p.m.
Learn basic techniques for sketching and journaling in the wild. All supplies and camper stools provided. Dress appropriately for the weather. Children 12 and under must be accompanied by an adult. Appropriate for ages 8 and up. Payment is due at time of registration. $15/Member, $18/Non-Member.
Register at: https://www.twnf.org/nature-events/nature-journaling-and-sketching-walk-workshop-june-22-2019/
Sunday, June 30, 1:00-6:00 p.m.
650 Sandy Bottom Road near Elkton Virginia, adjacent to Shenandoah National Park
Phone: (540) 298–8684
Heartflame Garden is a private garden and the home of Inanna and Gabriel Garretson. It is a very special 3-season display garden with about 1.5 acres of cultivated gardens and another 5 acres of rolling hills and streams to explore. This is a wonderful time to see the garden on an open-to-the-public day.
The Ornamental Garden in June
My husband and I went away for a couple of weeks in May, and when we returned our landscape looked overwhelmingly “verdant.” Some of the perennials, such as peonies, had come and gone; the weeds were on steroids; deer had bedded down on our old-fashioned bleeding hearts (Dicentra spectibilis); flowers needed deadheading. I felt a little out of sorts about having gone away at the height of the garden growth spurt. When I put my garden gloves back on, I reminded myself that there were life lessons to learn from facing a somewhat neglected June garden.
- Focus on the positive. (Not on the yellowing stalks of spring blooms)
- Let go of the past and be present in the moment. (The perennial bloom calendar, including peonies, goes marching on)
- Success is the sum of small efforts, repeated day in and day out. (Weeding)
- There is simply no substitute for hard work when it comes to achieving success. (Deadheading)
- Beauty is as beauty does. (Planting milkweed in the perennial garden)
- By failing to prepare, you are preparing to fail. (Composting and mulching)
- Happiness is not something you postpone for the future; it is something you design for the present. (Adding annuals for color in the perennial garden)
There are a lot of tasks in June that can keep the garden looking fresh and the plants happy.
Weeds seem to love hot weather. Adding another light layer of mulch can help keep down the weeds and maintain moisture in the soil which makes weed pulling easier. At this point in the season, more frequently-worked garden spots might need some additional mulch.
Daffodils, tulips, and other spring bulbs need to store food through their foliage. Daffodils continue to absorb nutrients for about six weeks after the blooms have died. You can either let them die back naturally, or cut them back after they’ve turned yellow. Do not tie or bind the foliage.
June often brings drier weather which means we need to water newly-planted plants, container plants, and any established plants that look wilted after even a short dry period. In times of drought, water infrequently and deeply, about 1” per week. For more info, see The Garden Shed June 2016 article, “Growing Things When the Rains Don’t Come.”
As soon as plants are allowed to set seed, chemical messages are sent back telling flower production to stop. Deadheading spent blooms short-circuits this message so that flowering will continue. Trimming off yellowing foliage also keeps the garden looking fresh when leaves are spent or have been damaged by slugs or insects.
When you pinch a plant with your thumb and forefinger, you remove the main stem, forcing the plant to grow two new stems from the leaf nodes below the pinch. You may remove just the new emerging leaves or down several inches to a side bud. Some plants, but not all, benefit from being pinched back to promote a bushier growth. Chrysanthemums and asters are two fall-blooming plants that especially benefit. Both plants can be pinched several times by July 4th. Stop pinching by this date or soon after so that you don’t interfere with bud production. Pinching back herbs, such as basil, helps the plants to produce more of their desirable leaves and keeps them from getting too leggy.
As the season progresses, some taller plants or top-heavy plants benefit from staking. If plants fall over, the stem will function poorly where it has been bent. If the stem is cracked, disease organisms can penetrate the break. Stake plants when you set them out so they will grow to cover the stakes. When staked, tall perennials can better withstand hard, driving rain, and wind. Select stakes that will be 6”–12” inches shorter than the height of the grown plant.
Many bushes should be pruned in June. Spring or early summer blooming shrubs such as azaleas, forsythia, lilac, deciduous viburnums, rhododendrons, and spring-blooming hydrangeas should be pruned after blooming but before new buds are set. Please see the shrub pruning schedule published by the Virginia Cooperative Extension.
The challenge and reward of creating a beautiful perennial garden is to create combinations of complementary colors and textures that roll through the season. Is it “cheating” to add annuals? Annuals are an asset that should be used! Lantana (L. camara, upright, and L. montevidensis, trailing) offers vibrant colors; globe amaranth (Gomphrena globosa) adds a huge pop of magenta; verbena (Verbena x hybrid), salvia, floss flower (Ageratum houstonianum), angelonia (Angelonia angustifolia), and so many others, add beautiful, ongoing color to the garden. See the June 2018 issue of The Garden Shed for additional information.
MORE TASKS AND TIPS
Lace bug damage is evidenced by yellow spots on the upper sides of the leaves. When feeding damage becomes severe, the leaves take on a gray, blotched appearance or can turn completely brown. As lace bugs feed, they produce brown varnishlike droppings that spot the underside of the leaves. When large numbers of lace bugs are present, cast skins can be found attached to the leaves. Lace bugs feed on the undersides of leaves with their piercing-sucking mouthparts, so check the underside of leaves for adults, nymphs, and small, black, smoke-stack-looking eggs. Adult lace bugs are about 1/8” – 1/4″ long with a netlike pattern on the wings. Nymphs are similar in appearance to the adults but are smaller and often have spines. Recognition of the host plant is helpful in identifying lace bugs because these insects are highly host specific (feed only on one plant or a closely-related species).
Azalea lacebug ( Stephanitis pyrioides ): Two generations of azalea lace bugs occur in Virginia per year. Try to control the first generation from mid-May to mid-June; two sprays may be necessary. The second brood builds up to high populations in August and September, and damage can be severe on azaleas that are planted in full sun. In some cases, the leaves turn completely brown and are heavily spotted with droppings by the end of the summer. The azalea lace bug was accidentally introduced from Japan.
Rhododendron Lace Bug (S. rhododendri): Treat in May or June to control the first generation. Rhododendrons growing in full sun may have a yellowish appearance from feeding by rhododendron lace bugs. The rhododendron lace bug is native.
Sycamore Lace Bug (Corythucha ciliata): Native to North America, insect damage is evidenced by a white stippling of the leaves that can eventually progress into chlorotic or bronzed foliage and premature senescence (aging) of leaves. In cases of severe infestations, trees may be defoliated in late summer. Heavy infestations are more common in urban areas than in natural settings. Damage is more severe during dry weather.
Lace Bug Control: Lace bug control requires careful monitoring early in the season. Control should be applied when insects are found on the foliage, either on adults on deciduous plants or on groups of nymphs on broad-leaved evergreens. It is very important to spray the undersides of the leaves because this is where they feed. A repeat application in 10 to 14 days will sometimes eliminate the need to control the next generation. For more information on cultural practices that deter pest damage, natural enemies of pests, and chemical solutions for serious infestations, see “Ask An Expert.”
Roses are a favorite of many gardeners, and unfortunately, to many insect pests as well! Inspect roses for aphids, mites, and thrips. Frequent inspections increase the likelihood that a pest infestation will be detected early, when pest numbers are low and control is easiest.
Control: Pests can be hosed off with a strong stream of water directed above and below the leaves. Spraying with water should be repeated frequently as needed, focusing in particular on new growth. For information on pest identification, natural enemies, and chemical solutions for more serious infestations, see Rose Insects & Related Pests.
INVASIVE SPOTLIGHT: WAVYLEAF GRASS OR WAVYLEAF BASKETGRASS
Japanese stiltgrass (Microstegium vimineum), an invasive plant common to our area, was highlighted in the June 2018 issue of The Garden Shed. This month’s invasive spotlight is on wavyleaf grass or wavyleaf basketgrass (Oplismenus undulatifoius), an invasive plant commonly found with Japanese stiltgrass. Wavyleaf was first discovered in the U.S. in Maryland in 1996; as of 2017, wavyleaf is known to be in fifteen Virginia counties, including Albemarle.
Wavyleaf’s rapid growth and dense roots and foliage have the potential to smother wildflowers, ferns, and other ground-layer plants, and to prevent forest tree and shrub regeneration. Invasions of this grass deplete food sources for mammals, birds, and insects and spell the destruction of our forests.
Although similar to each other in appearance, Japanese stiltgrass flourishes in both sun and shade, while wavyleaf grows only in shaded areas. Wavygrass leaves are rippled across their width and end with an elongated sharp tip. The leaf bases touch the stems but do not clasp or wrap around them, an important identifying characteristic. The stems are noticeably covered with short, white hairs.
Wavyleaf grass is a perennial, which gives it a decided advantage over invasive annuals such as Japanese stiltgrass. Wavyleaf emerges from dormancy and starts growing rapidly in April. It has ground-hugging, root-like stems, called stolons, which creep beneath leaf litter on the forest floor. Seeds germinate from April into June. Spikes of white flowers rise above the plants from August to November. The sticky seeds are produced first at the bottom of the spikes while new flowers bloom near the top.
Wavyleaf seeds hitchhike for miles by gluing themselves to animal fur and clothing. The sticky, difficult-to-remove seeds can remain attached for days or even months. Deer are one of the primary seed movers, as well as bears, other wildlife, hikers, hunters and pets.
Wavyleaf can be hand-pulled if populations are small, but all bits and pieces of stolons must be removed or they will re-sprout. Be sure to remove tiny seedlings, which resemble miniature, mature plants. Hand-pulling is ineffective in large areas of infestation.
Foliar Spray: Use a recommended grass-specific herbicide from April through June. This won’t harm wildflowers and is approved for wildlife management areas. Do not use a grass-specific herbicide in a wetland or near a stream, because of potential harm to fish and aquatics According to one study, grass-specific herbicides are less effective on wavyleaf in summer. After June, use a non-selective herbicide; this may also be used from April until frost.
NOTE: For currently approved herbicide recommendations, check the Virginia Department of Forestry chart, Non-Native Invasive Plant Species Control Treatments, which you can download from the Blue Ridge PRISM website
If you think you’ve found wavyleaf, take a photo and a GPS location. Report findings to Kevin Heffernan at the Virginia Department of Conservation & Recreation. Contact: 804-786-9112 or email@example.com.
“Daffodil FAQs,” The American Daffodil Society, https://daffodilusa.org/daffodil-info/daffodil-faqs/
“Garden Calendar,” The Morton Arboretum, https://www.mortonarb.org/trees-plants/tree-and-plant-advice/horticulture-care/garden-calendar
“A Guide to Successful Pruning, Shrub Pruning Calendar,” Virginia Cooperative Extension, https://www.pubs.ext.vt.edu/430/430-462/430-462.html
“Pinching and Pruning – A Perennial Primer,” University of Illinois Extension, https://web.extension.illinois.edu/cfiv/homeowners/060427.html
“Lace Bugs – Hemptera: Tingidae,” VCE, https://www.pubs.ext.vt.edu/3104/3104-1581/3104-1581.html
“Lace Bugs on Broad-Leaved Evergreen Ornamentals,” Penn State Insect Advice from Extension, https://ento.psu.edu/extension/factsheets/lace-bugs-evergreens
“Treatment for Lace Bugs on Azaleas and Rhododendrons,” Cooperative Extension, https://ask.extension.org/questions/304777
“Featured Creatures: Sycamore Lace Bug,” University of Florida, https://entnemdept.ifas.ufl.edu/creatures/trees/sycamore_lace_bug.htm
“Rose Insects & Related Pests,” Clemson Cooperative Extension, https://hgic.clemson.edu/factsheet/rose-insects-related-pests/
Wavyleaf Basketgrass, University of Maryland Extension, https://extension.umd.edu/hgic/topics/wavyleaf-basketgrass
New York Invasive Species Information, http://nyis.info/non-native-plant-assessments/
Report All Sightings of this Dangerous, Dreaded Invasive Wavyleaf Grass or Wavyleaf Basketgrass, https://blueridgeprism.org/factsheets/
Innovative Ways with your Garden Greens
Kale, kale, the greens are here!
Did you ever wake up with the sunrise and just start grazing on the wonderful organic greens in your garden? Well, stop it! The neighbors are staring at you! The good news is that organic greens is our topic this month. On my occasional days off, I indulge in zesty fresh salads and my favorite green smoothies which add fiber and nutrition to balance out my fried chicken obsession.
Here are some tricks I’ve tried with greens that you might enjoy this summer.
Take your ugly, broken spinach and put it in your blender; add ice cubes, blend, and strain into a glass. To me, the cold and calcium content tricks my mind into thinking it’s actually milk.
Take the root of fennel & shave it thin using a mandolin slicer. Add arugula. Toss it with olive oil & sesame seeds.
Top it with shaved radish and crumbled feta cheese.
Thyme Margarita (semi-virgin)
Put a spoonful of tequila inside your chosen margarita glass, then light a sprig of thyme on fire and place it into the glass to char for a minute. Remove the burnt sprig and add a fresh one. Then add ice, agave nectar, a lime wedge, and triple sec. Add tequila if you desire authenticity.
Take canned tuna or leftover rotisserie chicken and add your favorite coleslaw.
You could take it one step further and chop up some other greens or herbs for extra flavor.
What do you have growing that could contain this? Hmmm? Bibb, Romaine, Bok Choy, Squash blossoms?
Kohlrabi Tacos (gluten free)
Use a mandolin to slice a kohlrabi into rounds that become “taco shells.”
Fold shells in half, place in between a wire rack and bake at 350° for 10 minutes.
Get creative with the filling by adding broccoli florets, diced red peppers, diced tomato, shredded root vegetables, and top it with Greek yogurt or Tzatziki sauce (recipe coming soon, or go ask a Greek neighbor.)
Dandelion Fritters (too late for this season)
Dip dandelion blossoms in some loose pancake batter and deep fry. Just that simple and tastes great.
Hopefully, your cookout guests can appreciate some of these treats, but if they don’t, just love them for the poor misguided lost souls that they are and keep preaching the goodness of the greens. Have a wonderful summer!
Container Gardening II: What to Grow & How
Last month we talked about choosing containers, preparing your soil and siting your containers. Now it’s time to start planting.
Deciding what to plant and developing a scheme are unquestionably the most appealing aspects of container gardening. The options seem almost endless! Even after you narrow your options to a category of botanicals, shrubs/small trees, herbs, or vegetables, your decisions may still involve some thought and planning depending on your space, time, budget, and aspirations. This article provides an overview of some basic concepts to get started. If you are feeling overwhelmed with all the possibilities or need more inspiration, consult with online resources and library books. The Jefferson Madison Library has a collection of materials devoted to container gardening with abundant pictures and design suggestions.
Botanicals and Ornamentals
Small trees and shrubs such as a Japanese maple (Acer palmatum) or yucca (Yucca filamentosa, ‘Golden Sword’) can live successfully in a well-insulated container and remain outside through the winter. Some varieties of roses can also be cultivated in containers. Select a hybrid that is compact and relatively small (expected height of 24 to 30 inches) and disease-resistant (especially to black-spot). Large tropical plants and small citrus trees can spend the summer outside in containers, but will need to come inside for the colder months.
Grouping flowers with ornamental grasses and foliage creates an attractive container garden. Choosing plants with similar light, temperature, and water requirements contributes to the health and maintenance of the container’s contents. Use your creativity and imagination to incorporate color, texture, proportion, and shape into the presentation. A “thriller, filler, spiller” design is one concept to try. Place one plant in the center to ‘thrill’ the eye and draw attention, ‘fill’ the planter with an accenting color, and pick one or two plants to ‘spill’ over the sides to soften the appearance.
A Thriller, Filler, Spiller for Shade or Partial Sun Pictured at left is a recently-planted flamboyant centerpiece with a colorful coleus ‘Twist and Twirl’ (Plectranthus scutellarioides), contrasted with dahlias (Dahlia pinnata) which will bloom in vibrant shades of yellow, and the thin leaves of two ‘Silver Sand’ cushion bushes (Calocephalus brownii), surrounded by ‘Silver Falls’ dichondra (Dichondra argentea) for a showy display of delicate leaves flowing out of a large container.
One approach is to exchange plants as the seasons progress. In the early spring, containers are filled with pansies, violas, primulas, lobelia, dianthus, snapdragons, daffodils, and tulip bulbs. Summer is heralded with lively hues and the necessity to work with heat-tolerant plants. For instance, SunPatiens® flourish in sun, heat, and humidity. Marigolds, zinnias, geraniums, petunias, miniature sunflowers, and dahlias brighten containers through fall. Tropical plants, such as caladium, banana, mandevilla, and canna bulbs will explode with color and foliage during the summer but require some TLC if you want to try and preserve them through the winter. Favorite choices for the fall season include mums, calendulas, pansies, and ornamental kales.
Urban dwellers and gardeners seeking a way to create a pocket-sized vegetable garden may find containers offer a flexible solution. The appeal of fresh-picked produce has contributed to the development of specially-bred “pot-friendly” tomatoes, eggplants, cucumbers, and other vegetables. These container-specific varieties are not dwarf or miniature; instead, they are usually more compact and capable of producing a plentiful harvest.
Guidelines for planting vegetables in a container are similar to those established for a garden bed. Popular choices include tomatoes, lettuces of all types, collard greens, leafy greens, peppers, and eggplant. Cucumbers, sweet potatoes, and other plants with vines can do well as long as they have room to sprawl with support. Once you choose what to plant, attention should be given to the planting schedule, container selection and preparation, spacing of plants, light, water and nutrition requirements, and maintenance.
For instance, if you decide to grow tomatoes, you will want to select a variety that thrives in a container. Determinate variety tomatoes — such as ‘Celebrity’, ‘Tasmanian Chocolate Organic’ or ‘Plum Regal’ — are characteristically compact and bushy. Indeterminate hybrid varieties, such as ‘Firecracker Hybrid,’ offer options for other tastes. A single tomato plant requires a five-gallon planter placed to get eight hours of sun a day. Timing for planting seeds or starters should be followed with consideration for the plants’ susceptibility to extreme high temperatures — over 95º F. Container tomatoes require supports, frequent watering, persistent fertilization, and vigilant monitoring for pests and diseases.
To help you get started, the chart below shows the minimum container size and spacing needed for planting vegetables. Consult the Virginia Cooperative Extension website at https://ext.vt.edu/ or one of the references at the conclusion of this article for specific growing information for each type of plant.
Minimum Container Size and Spacing Needed for Vegetables in Containers
| MINIMUM SIZE
|2 – 3 inches
|2 – 3 inches
|1 plant per container or 12-16 inches
|1 plant per container
|1 plant per container or 14 – 18 inches
|1 plant per container
|1 plant per container
North Carolina Extension Gardener Handbook, North Carolina State University,https://content.ces.ncsu.edu/extension-gardener-handbook/18-plants-grown-in-containers#section_heading_8772.
A window box brimming with an array of flavorful culinary herbs, such as chives, Italian parsley, and thyme is an irresistible addition to any kitchen garden. Some herbs are natural companions for vegetables or botanicals. For example, it seems that basil, planted with tomatoes, acts as a deterrent for white flies, tomato hornworms, aphids, mosquitoes, houseflies, and asparagus beetles. If you are working with children, herbs offer an enticing way to introduce the dual pleasures of gardening and cooking while appealing to their senses.
Herbs requiring well-drained soil and tender plants needing to be overwintered indoors are particularly suitable for container gardening. Among the most commonly recommended and grown are variegated sage, purple or golden sage, parsley, Greek oregano, rosemary, marjoram, basil, thyme, chives, and summer savory. Also, chamomile, lemon balm, feverfew, lavender, and a variety of mint flavors can be grown for tea or medicinal purposes. Growing mint in the confines of a container can be helpful even if you could plant it in the ground. The container will keep it from spreading and overtaking the garden bed.
Typically, herbs thrive in sun or part shade. They can be started inside and moved outside relatively early in the spring. Soil management is critical. Herbs do not tolerate squelchy conditions and some plants, such as rosemary, prefer a coarse, sandy-textured medium. Snipping sprigs encourages growth and a continued source of leaves to harvest and enjoy
Once the containers are planted, you will have the joy and fulfillment of watching them flourish and produce. Of course, this does not come without an investment of time and effort in maintaining the well-being of the plants. Following some simple procedures will yield satisfying results!
Unlike a garden bed that has a natural watershed, a container dries out quickly. Clay or terracotta receptacles absorb moisture from the soil and small pots require watering more frequently. Numerous gadgets to test moisture levels are available; however, your finger is really the best tool. Put your finger in the top inch of soil to determine if it is wet or dry and observe the foliage for severe wilting (needs water) or yellowing leaves (overwatering). It is best to water early in the day and before plants show signs of stress from drought. Keep the foliage dry and apply enough water each time so the whole soil ball becomes moist. Water should start to drip out of the base holes. As emphasized earlier, drainage is crucial. Elevating the container with feet will increase ventilation and prevent the pot from sitting in a pool of water.
Specifically, how much and how often to water depends on several variables:
- location of the container
- time of year
- weather conditions (how much has it rained?)
- length of time container has been planted (stage of plant growth)
- type of container
- variety of plants and soil medium
A wide variety of watering apparatuses is available to keep containers irrigated. A watering can or garden hose is the most familiar and commonly used. Garden hoses can be accessorized with a wand to assist with hanging planters or hard-to-reach pots. If an outside water source is not available, a lightweight, expanding/collapsible hose can be fitted with an adapter and attached to an inside sink, then pulled outside or to a balcony. Self-watering planters and drip irrigation systems are other options but require monitoring to ensure that overwatering does not occur.
Leaching, when water removes soluble elements from the soil, reduces the concentration of essential nutrients, such as nitrogen and phosphorous. Rain and frequent watering quickly deplete plants of the nutrition vital for growth. A regular schedule of fertilization will reinforce plant health and longevity by enriching the soil and replacing nutrients.
Slow-release fertilizer consists of a water-soluble product that is encased in a semi-permeable resin coating. When the pellets come in contact with water, small amounts of nutrients are released to the soil for use by the plant. Notably, the time that they last is based on temperature (usually 70º F.). The warmer it is, the faster they release nutrients. A four-to-five-month pelleted fertilizer may only last two months if the temperatures are above 85º F. Some potting mixes come amended with slow-release fertilizer; otherwise, gardeners often add it themselves during planting.
Another option is water-soluble liquid fertilizer. It is mixed with water and applied approximately every two weeks. Frequency can be adjusted based on the overall appearance and growth of the plants. Water-soluble fertilizers have minimal temperature dependence. The choice of fertilizer analysis depends on the kinds of plants growing. For example, high-nitrogen sources would be good for plants grown for their foliage, while flowering and vegetable crops benefit from lower nitrogen and higher phosphorous type products, e.g., 9-15-30. If organic fertilizers are preferred, consider a combination of fish emulsion, kelp meal/extract, greensand, and bone meal. Kelp extracts and meal are very advantageous as they are good sources of micronutrients.
Foliage and botanicals with vines, top-heavy flowers, plants with weak stems, and some vegetables require assistance to remain upright or disentangled. Tall plants situated in areas that are subject to heavy rain or high winds may also benefit from supports. If a support is needed, it should be anchored firmly into the soil at the time of planting.
Stakes provide a simple basic support system. They are available in several lengths and made from many materials (bamboo, wood, plastic, and wire). No matter what type is used, stakes should not be prominent or higher than the plant. Twist ties or string can be used to secure the plant to the stake. Care should be taken not to damage the stem by pinching or choking when securing the tie. Additional ties should be added as the plant gains height.
Adjustable metal hoops, “grow-throughs,” cages, towers, grids, and trellises provide more customized configurations. Garden suppliers offer creative unobtrusive solutions or ornamental alternatives to embellish the garden decor. Do-it-yourself possibilities are available from Pinterest. Ultimately, the choice of a support should be based on the anticipated growth habits and vigor of the plant.
Grooming and Pruning
Clearing containers of dead leaves, spent blooms, and other debris is not the most glamorous aspect of container gardening; however, it is a building block of horticulture maintenance. Constant high humidity next to moist soil on warm days, and lack of air movement around closely-set plants, coupled with decaying plant material, is a recipe for trouble. Conditions in unkempt containers are favorable for the spread of fungal diseases, such as botrytis (gray mold). Regular surveillance and clean-up serve to keep the garden’s gems looking and growing at their best.
Pruning promotes healthy plant development and can impact the façade of the container. Pinching and deadheading are techniques routinely used during the growing season. Cutting back is done at different times of the year depending on the purpose.
- Pinching: Snip off the growing tip of the stem using a fingertip. New lateral stems will grow from the stem that was pinched and it will then set buds. This procedure can improve the shape and appearance by encouraging a more compact, bushier plant and reduce tall, leggy spurs.
- Deadheading: Remove old flowers by clipping off the spent blooms. This practice extends the flowering season by stimulating plants to continue blooming. Self-cleaning annuals and perennials that drop their flowers as they fade and do not need deadheading include: Wax Begonia (Begonia semperflorens), Coleus (Coleus blumei), Edging Lobelia (Lobelia erinus), Asteromoea, (Asteromoea mongolica), Coreopsis (Coreopsis verticillata), and Phlox (Phlox divaricata).
- Cutting back: Prune down from the top or crown with a significant cut, or to the soil level for declining perennials or ornamentals. This technique is usually accomplished during the dormant period and promotes vigorous new growth once the next growing season ensues. Over the spring and summer, flowering perennials and annuals may benefit from cutting back. Perennials have varying prime times. If executed at the right point, this method can prevent plants from becoming woody or lanky. Similarly, annuals can be rejuvenated in mid-summer by cutting back to a stem of three to five inches with only four or five leaf nodes. Petunias (Petunia x hybrida) and impatiens (Impatiens balsamina) respond particularly well to this intervention.
In our climate, many plants cannot survive outside in containers during the winter months. The particular conditions of the microclimate, the protection provided by the pot, and the specific plants will determine if shelter is needed for the winter. Damage from the cold can easily occur since the temperature of the container is the same as the air temperature. As the most vulnerable part of the plant, the root system is susceptible to freezing and not as well-insulated as it would be in the ground.
A rule of thumb for selecting plants that might manage the winter is to consider those that are designated for two or fewer USDA hardiness zones below where you live. For the Charlottesville-Albemarle area in Zone 7a, that would be plants assigned to hardiness Zone 5 or lower. Hardy perennials (chrysanthemums or pansies), cold-weather vegetables (kale or collards), a few herbs (rosemary or sage) and most non-tropical shrubs and trees should be able to survive most winters. Move containers to a protected area or near a building and consider an additional layer by wrapping with a frost blanket, quilt batting, or household insulation covered with plastic (to avoid soaking during wet weather). Shredded bark mulch can help regulate soil moisture. Alternatively, cut branches from evergreens, like spruces, pines, and arborvitae, can be placed into the soil all around the base of the plant for added protection. If the temperatures go above freezing, keep the plants watered to help protect against frost damage.
Tropical plants, many perennials, and most herbs need to move inside for the winter. It is best to begin the process gradually before the heat is turned on inside and well before the before the first frost. With a grow-light or a sunny window location and adequate humidity, you can continue to harvest some herbs. Generally, plants do best in an environment away from the drying air of heating ducts and cold drafts from outside doors or windows. Depending on the specific cultural requirement of the plant, a basement or garage may be the ideal winter abode for dormancy.
As the saying goes, “An ounce of prevention is worth a pound of care.” The combined time, planning, effort, and materials put into a garden warrant guardianship of your investment. A proactive approach will contribute to sustained success and reduce issues associated with disease and pests.
Practice Good Hygiene
Containers, especially large-sized pots, do not always need to be cleaned before re-potting The top soil should be refreshed and amended with fertilizer. If there is evidence of plant disease or if a plant dies, the pot should be completely emptied. Scrub the container thoroughly with soap and water and rinse with a solution of ten percent bleach before reusing.
Survey Containers Regularly
Check the containers, soil, and plants daily. Look for insects, disease, or symptoms of overwatering/dryness. Promptly remove any leaves and stems that show signs of a problem. Examine the soil and area around the base of the plant (collar) for signs of root rot or other fungal disease.
Container-grown plants are vulnerable to many of the pests and diseases that occur in a garden bed. As soon as you spot a problem, try to determine a diagnosis and implement an intervention. If you are unsure, have questions, or are puzzled with a challenge, get help! An invaluable local resource is the Piedmont Master Gardeners Horticulture Help Desk. For personalized assistance, call (434-872-4583) Monday – Friday, 9:00 a.m. – 12:00 p.m. or e-mail (firstname.lastname@example.org) and attach pictures with a description of your observation. Go to https://piedmontmastergardeners.org/gardening-questions/ for more information about the Horticulture Help Desk and to learn about Mobile Help Desk locations and dates.
Your Best Garden Ever
Whether you start with one simple unit or expand to a collection, make the most of your container experience this season. Follow the steps for preparation, plant selection, maintenance, and prevention for a robust and dynamic garden. It could be your best!
“The Art of Container Gardening,” Pennsylvania State University Extension, https://extension.psu.edu/the-art-of-container-gardening
“General Recommendations for Growing Vegetables in Containers,” Pennsylvania State University Extension, https://extension.psu.edu/general-recommendations-for-growing-vegetables-in-containers
Container Gardening: How to Select, Plant, and Maintain, Illinois Cooperative Extension, https://extension.illinois.edu/containergardening/welcome.cfm
“Container Gardening Planting Calendar for Edibles in the Piedmont,” North Carolina State University Extension. https://content.ces.ncsu.edu/container-garden-planting-calendar-for-edibles-in-the-piedmont
“Container Gardening,” University of Missouri Extension, AgrAbility Project, http://agrability.missouri.edu/gardenweb/Container.html?_ga=2.118169870.608999211.1552242785-1564651425.1552242785
“Success with Container Production of Twelve Herb Species,” North Carolina State University Extension, https://content.ces.ncsu.edu/success-with-container-production-of-twelve-herb-species
“Common Problems in Container Gardens,” University of Maine Cooperative Extension Publication 2765, https://extension.umaine.edu/publications/2765e/
“Growing Vegetables and Flowers in Containers,” Pennsylvania State University Extension, https://extension.psu.edu/growing-vegetables-and-flowers-in-containers
National Gardening Association Learning Library, “Annuals and Perennials for Containers”, https://garden.org/learn/articles/view/2161/?utm_source=nl&utm_medium=mail&utm_campaign=nl_2019-03-02
“Container and Raised Bed Gardening,” Virginia Cooperative Extension Publication 426-020, http://pubs.ext.vt.edu/426/426-336/426-336.html
North Carolina Extension Gardener Handbook, Chap. 18: “Plants Grown in Containers”, North Carolina State Extension, https://content.ces.ncsu.edu/extension-gardener-handbook/18-plants-grown-in-containers#section_heading_8769
Relf, Diane, “Vegetable Gardening in Containers,” Virginia Cooperative Extension Publication 426-336, http://pubs.ext.vt.edu/426/426-336/426-336.html