A Shady Perennial Garden

Source(s):  Rebecca Pickett

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Herbaceous perennials usually die back in winter and reappear each spring to thrive and bloom again. They don’t always live forever, nor are they free of maintenance.

GET READY …

• Good bed preparation is essential for the growth of healthy perennials. Prepare all beds in the summer for fall planting and in the winter for spring planting. Correct drainage problems before planting.
• Check the drainage by running a percolation test. Dig a 10″ hole and fill it with water. The next day, fill the hole with water again and time how long it stays in the hole. If the water is gone in 8-10 hours (1″ per hour), this site is suitable for most perennials.

BED PREPARATION …

• Dig or till your soil 8 inches deep.
• Remove all this worked soil and set it aside (your topsoil). -With a spading fork loosen the next 8″ of soil and work in coarse (granite) sand or wood chips.
• Replace your topsoil and mix in 4″ of coarse sand or granite dust and 4″ of organic material (compost, shredded bark, etc.). This results in a 24″ thick layer of improved soil.
• Add lime and fertilizer as recommended by your soil test. (Barbara Allen)

GET SET …
Resist the urge to plant one of each kind. Use odd numbers of plants (3,5,7) and plant them in asymmetrical groups or “drifts.” The visual effect of this type of planting will be more effective than a polka-dot or geometric design.

RECOMMENDED PERENNIALS FOR PARTIAL SHADE: (Afternoon shade or dappled light under trees)
PROPER NAME	(COMMON NAME) ‘BEST VARIETY’	FLOWER COLOR	HEIGHT BLOOM TIME	COMMENTS
Ajuga reptans	(bugleweed) ‘Burgundy Glow’, “Atropurpurea’	blue, lavender, pink, white	4-12″, late spring	Ground cover grown mainly for foliage. Several types available.
Anemone vitifolia	(grapeleaf anemone) ‘Robustissima’	pink	11/2-3′, early fall	Spreads rapidly. Nice foliage all summer. Also try A. japonica.
Aquilegia canadensis	(Canadian columbine)	red & yellow	1-2′, spring	Better here than the hybrids.
Astilbe arendsii	‘Deutschland’; ‘Fanal’; ‘Rheinland’, ‘Finale’	white; red; pink	1-3′, late spring	Lovely feathery blooms. Needs lots of water. Watch for spider mites.
Astilbe chinensis	‘Pumila’	pink	1-2′, spring	Needs less water than arendsii.
Digitalis mertonensis	(strawberry foxglove)	rosy pink	3-4′, summer	Lasts 2 or 3 years. Very pretty.
Heuchera americana	(alum root) ‘Sunset’	greenish white	1-11/2‘, summer	Does better than hybrids.
Heuchera micrantha	(alum root) ‘Palace Purple’	creamy	1-11/2 ’,summer	Grown for its purplish foliage.
Lobelia cardinalis syphilitica	(cardinal flower) (big blue lobelia)	red blue	2-4′, late summer	Must have rich, moist soil. Likes stream banks. Reseeds like crazy.
Phlox divaricata	(woodland phlox) ‘Fuller’s White’ ‘Louisiana’	white blue	12-15″, spring	Evergreen, spreads slowly. This native should be used more.
Tiarella cordifolia	(foamflower)	white	6-12″, spring	Rich, moist soil, not much sun.
Tradescantia virginiana	(spiderwort) ‘Snow Cap’ ‘Zwanenburg Blue’	white deep blue	1-2′, summer	Blooms mornings & cloudy days. Will take a good bit of sun.
FOR FULL SHADE: (meaning little if any direct sunlight)
Begonia grandis	(hardy begonia)	pink	2′, late summer	Angel-wing leaves. No dividing.
Brunnera macrophylla	(heartleaf brunnera)	light blue	18″, spring	Forget me-not flowers, big heart­ shaped leaf. Goes dormant in heat
Chrysogonum virginianum	(green and gold) ‘Piccadilly’	yellow	6-9″, spring	Thick mat of foliage. Blooms on and off all year. Evergreen.
Dicentra eximia	(fringed bleeding heart)	pink, white	1-1½’, spring	Better than spectabilis for heat.
Dicentra spectabilis	(common bleeding heart	pink, white	1-1½, spring	Beautiful sight in spring.
Helleborus orientalis	(Lenten rose)	shades of deep rose to white	18”, February	Evergreen foliage. Flowers las a long time. Reseeds prolifically.
Hosta	(plantain lily, funkia) hundreds	White, lilac	6” – 4”, summer	Grow different kinds for contrast of foliage. The shade plant here.
Iris cristata	(crested iris)	Blue with yellow crest	6”, late spring	Spreads quickly. Charming dwarf.
Mertensia virginica	(Virginia bluebells)	Blue	1-2’, early spring	Dies back after early bloom. Nice.
Sanquinana canadensis	(bloodroot	White	6”, early spring	The harbinger of spring
Trillium grandiflorum	(wake-robin)	None	1-2” early spring	Spring delight. Cutting will kill.
Ferns	Japanese Painted Fern, Christmas Fern (evergreen), Maidenhair Fern (evergreen), Japanese Shield Fern	None	12” and up	There are various textures and heights to try. They offer a pleasing contrast to the leaves of hostas and can fill in where early spring bloomers have died back

GROW

• Best planting time in Atlanta is near Oct. 15 or April 1.
• Loosen root balls and set the crown no deeper than it was before.
• Firm soil gently around roots and water deeply.
• Markers will help identify and protect. Put stepping stones in wide beds to limit soil compaction caused by footsteps.
• Heavy winter mulch is not recommended here; it encourages crown rot. A 1 1/2 to 2′ summer mulch of pine straw, bark or wood chips is necessary to hold moisture in and keep weeds out.
• Once established, fertilize your bed with 1 1/2 lb, of 8-8-8 or 10-10-10 per 100 sq. ft. in early spring and again during late spring and/or midsummer. A pound of granular fertilizer is equal to about 2 cups.
• Water deeply once a week during dry spells. Avoid frequent, shallow watering or watering late in the day. Wet foliage promotes disease problems.
• Keep weeds, dead foliage and spent blooms removed.
• Some plants will need staking. Try bamboo stakes and soft jute twine, or cut up tomato cages.
• When foliage dies in fall, clean it out and do not let leaves pile up in winter. Yep, crown rot again! Give the bed a good cleanout in spring and add new mulch as summer heat approaches.
• Some plants will need dividing every two or three years, others will not. Divide and share with friends.

POSSIBLE PROBLEMS…

• Snails or slugs: They eat leaves and leave a slime trail. Try beer in saucers or crushed eggshells around plants.
• Spittlebuq: Deposits foamy ‘spittle’ in crown or leaf joint. Try rotenone or recommended insecticide.
• Mealybug: Small, cottony spot on stem. Blast off with hose or touch with alcohol swab.
• Leafminer: Leaves trails in leaf of columbine. Pick off leaf or use appropriate pesticide.
• Aphids: Clusters of oval green/black/brown specks on leaf or stem. Blast with hose, use insecticidal soap or an insecticide.
• Thrips: Cause malformed, brown flower buds. Pick off affected buds or use insecticide.
• Spider Mites: Cause a stippled white or dried out look on leaves. Daylilies turn bronze or yellow. Blast with hose or use a miticide.
• Powdery Mildew: A white haze develops on leaves, especially phlox and crepe myrtle. Use a recommended fungicide for both prevention and treatment.
• Crown rot, Root rot: Just about any plant will succumb to these if planted too deeply or allowed to have wet feet for too long.

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Many thanks to the following for the benefit of their ideas:

• Barbara Allen, Master Gardener (Her ‘Recipe’ for preparing a bed is one of many methods.)
• Allan M. Armitage, The University of Georgia
• Jane Bath, Land Arts, Inc,, Monroe, GA
• Jimmy Stewart, Garden Designs, Atlanta, GA
• Chuck Zdeb, Master Gardener

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Resource(s): Flowering Perennials for Georgia Gardens

Center Publication Number: 1