How To Choose The Best Shade Perennials For Your Garden
The best color perennials for shade depend on three factors: how much shade you get‚ whether your soil is wet‚ dry‚ or average‚ and about when you want color․ Full shade (no direct sunlight) needs an entirely different plant selection than dappled or partial shade (2-4 hours of morning daylight)․ Buying the wrong plant is the number one reason shade gardens disappoint․ Below‚ we'll describe how to match plants to your conditions and suggest seven native perennials to try in Tennessee's woodland understories․
Start by mapping your shade․
Before you buy your first plant‚ walk your garden bed at different times of the day for a few days․ Is it shaded all day by a building or evergreen canopy (full shade)? Does it get filtered light through deciduous trees (dappled shade)? Or does it get a few hours of direct sun‚ usually in the morning before the trees leaf out or before the afternoon sun moves in (partial shade)?
This is more problematic in Tennessee than in a region with a humid‚ open environment; summer heat and humidity stress any plant receiving too much sun after noon with insufficient cover․ For example‚ a perennial is rated for partial shade in a cool northern state‚ but may need full-shade protection in August in a Zone 7 setting․
Soil Type And Moisture
Most woodland shade perennials evolved in forest shade where the soil remains moist from decaying leaf litter․
- Drainage is just as important as moisture‚ where soggy‚ compacted clay such as that of Middle Tennessee can rot the roots of Trillium and Solomon's Seal as fast as a drought can kill them․ Amend the soil with work compost or leaf mold to improve drainage‚ and improve moisture retention in clay soils․ - pH is usually slightly acidic․ Most of the plants in the following list prefer soil in the 5․5 to 6․8 range‚ which is common to the naturally acidic‚ tree-covered soils of Tennessee․ If you are gardening near a foundation or have limestone soils‚ as is often the case in the hills of Middle and East Tennessee‚ a soil test will tell you whether you need sulfur additive․ - Use mulch․ A 2-3 inch layer of shredded leaves or hardwood mulch‚ like that found in the forest‚ helps maintain moisture and cool roots of plants that require it․
Bloom Timing And Layering Color
Over-reliance on spring bloomers might be another problem: many shade-loving natives bloom before tree leaves fully open and spend the rest of summer dormant or as a green background foliage․ Layer in later blooming plants and foliage plants with spring ephemerals to create several seasons of interest in a shade garden from April until fall‚ with evergreens for all-year structure․
Seven Shade Perennials Worth Planting
It blooms in early to mid-April․ The mottled green-and-maroon leaves rise above the ground‚ and a single upright yellow flower emerges from each plant․ Yellow trillium is slow to get established (it takes two to three years until it puts out a flush of blooms)‚ but the colony can last for decades․ It prefers full to partial shade and the soil that does not dry out․
One of the easiest natives to use is Wild Geranium‚ with its pinkish purple saucer-shaped flowers blooming from late April through June․ It tolerates a wider range of conditions than most other shade perennials‚ from rocky well-drained outcrops to rich woodland soil‚ and self-sows modestly to eventually fill in․
Virginia spring beauty is a low-growing groundcover plant with purple-pink-veined white flowers․ It is one of the first plants to bloom in Tennessee's woods‚ often appearing as early as late February or March․ However‚ as an ephemeral the foliage dies back by early summer‚ and so it may be planted where perennials will grow in its place․
Virginia Bluebells are the number one wildflower for me․ Clusters of bell shaped blue (or pink-tinged) flowers appear in April on 1-2 foot stems․ Mature patches can look like a small blue river running through a shade bed․ Like Spring Beauty they have a short window of presence‚ often disappearing by midsummer․ They work well with hostas or ferns‚ which take over visually once the bluebells have disappeared․
The common name‚ twinleaf‚ is based on the structure of the leaf‚ which is divided in half‚ each half with a leaf base making it look like two leaflets at a base․ The flowers are creamy white‚ short-lived (making a show for only a day or two in early spring)‚ the foliage attractive through summer․
Heart-shaped white flowers appear in April on delicate fern-like foliage‚ producing a very sweet odor․ Squirrel Corn is usually not seen in bloom until the colony has matured a few years‚ since it gets established by a number of underground bulblets (the "corn" part of the name)․ Deer tend to leave it alone‚ which is a big plus in a Tennessee garden adjacent to woods․
The most utilitarian of the group is Solomon's Seal․ The stems arch and carry small white bell-flowers in late spring; they retain their shape and green color until autumn‚ providing a skeleton of green in the shade bed long after the ephemerals have gone dormant after flowering․ It tolerates drier shade better than most plants on this list‚ and is a good choice for poorly watered areas near tree roots․
Designing With These Plants
Think in layers‚ the way a real forest is layered․ Put the late bloomers (like Solomon's Seal) toward the rear or as a mid-height anchor‚ have the ephemerals (Bluebells‚ Spring Beauty) take the ground early in the year‚ and place the slower spreaders (like Trillium‚ Twinleaf) somewhere they won't be overwhelmed until they're big enough to compete․ Space most of these 12-18 inches apart and allow them to spread out․
Many of these shade perennials may also be obtained via TN Nursery as field-grown‚ nursery-hardened stock suited to Tennessee and Southeast conditions‚ which is helpful relative to mail order plugs not yet acclimated to our clay soils and fluctuating humidity․
A Few Practical Notes
Water new plantings weekly until established in their first growing season‚ even those in shaded areas; shade does not equal drought-tolerant․ Do not fertilize until a soil test shows a definite deficiency and even then‚ woodland natives may become too leafy and not flower because of excess nitrogen․ Patience․ Most of these plants will reward a few seasons of establishment with decades of low-maintenance beauty‚ as long as you give them time․
