Monday, August 17, 2009

Natural Color for Shady Landscapes

One of the most daunting challenges facing the average gardener is planting in full shade. Not the partially sunny, light-dappled kind of shade that feels so lovely in midsummer, but the deep Amazonian shade so dark that moss will grow on your garden trowel if you don’t keep moving. Not surprisingly, many folks facing full shade simply give up and resign themselves to a dull landscape of invasive ivy and much over-utilized liriope, little realizing that there are ways to foster splashes of vibrant color even in their horticultural twilight zone.

One possible approach is to treat a fully shaded yard more like a natural woodland area, selecting a variety of native plants which are generally well-suited to low light conditions.

You might start by seeing whether your landscape can use some small trees and shrubs. For example, while many yards are full of tall, mature trees, such as oaks, hickory, and poplars, there is usually little else growing between the sky-high canopy and the ground below. Filling that space, the “understory,” is the first best place to begin adding color.

Some suggested specimens include Shadbush, which provides white flowers in spring and brilliant foliage in autumn, and Redbud, which also features pinkish-purple spring flowers and red leaves in fall.

Fringe tree is one of the true delights of our local woodlands with extremely fragrant, pendulous clusters of bright white flowers, as is Sweetbay Magnolia, with large aromatic white flowers and brilliant red berries.

Virginia Sweetspire produces long, fluffy racemes of fragrant white flowers in summer, followed by wine-red foliage through autumn and early winter.

And finally, round out these aromatic offerings with Sweet Pepperbush (Summersweet), with its tempting midsummer display of apple-pie scented, pinkish-white flower spikes, usually heavily-visited by butterflies, and an encore of yellow foliage in fall.

Beneath the understory, you will want to introduce a full array of woodland wildflowers, which can expand or reflect the key elements of this region’s natural habitat. Be sure to keep succession bloom in mind as you select your plants. For example, a great many woodland plants will put on a fine show in early through mid-spring but these “ephemerals” will soon fade, leaving you with foliage and fond memories.

That is not to say that you should not include spring ephemerals, which are often among the most spectacular plants around, such as Virginia Bluebells, which explode in April yet sadly fade in May. But think in terms of plants which will flower at different periods throughout the year, and which can do double or triple duty with autumnal color and/or colorful fruits and berries.

Some native selections, such as Great Blue Lobelia and Columbine, also readily attract butterflies and hummingbirds, which is yet another way to introduce color into your garden – and into your life!

Great Blue Lobelia should also be greatly valued for its brilliant bluish-purple tubular flowers. These appear on one-to-three foot long spikes which bloom from August through October. The species is cousin to the showier Cardinal Flower, but performs far better in partial to full shade. Moreover, the spikes also make for excellent cut flowers, if you can bear the thought of removing them from your garden.

Our native Columbine is favored for its nodding, bell-shaped flowers with tubular red petals or “spurs” and yellow center or “lips” which appear through April and May. The foliage provides a variety of color as it changes during the year from green to shades of maroon. It also reseeds easily, helping it to fill in spaces like a ground cover. Note that in addition to the native species, there are cultivars available which can offer extended blooming periods and exquisite color combinations, such as creamy white flowers with golden centers.

Dutchman's Breeches is another ephemeral native with small, fanciful white and yellow flowers on arching stems or “scapes” and delicate, fine-cut light green foliage. Unfortunately, the flowers only appear from early to mid spring. On the other hand, a close relative, Wild Bleeding Heart, provides the same light touch with wispy mounds of seemingly etched foliage, but with delicate rosy-pink, sometimes purplish, heart-shaped flowers that last from mid-spring through fall.

Alumroot (Heuchera) provides year-round interest with semi-evergreen ruffled leaves which often appear silvery-white with a network of green veins. Some plants also show splotches of reddish-purple, which will spread across the leaf surface and turn progressively darker as summer creeps towards cooler weather. Slender stems or panicles with small bell-shaped flowers appear from April through June. Alumroot makes an excellent ground cover or edging plant if established in thick masses. And look for some of the popular cultivars, like ‘Coral Bells’ which features much darker green leaves, bright, almost reflective silver highlights, and deep red veins.

Foam Flower is another excellent ground cover which spreads readily through underground rhizomes and seeds. Like Alumroot, it is also semi-evergreen, with green foliage that turns maroon as the weather gets nippy. White flower spikes appear from early spring through midsummer, although hybrid varieties, such as ‘Spring Symphony,’ develop spikes of flowers in a pastel pink, almost 18 inches tall, which will last from summer through fall.

For a bit more height in your understory, consider planting several masses of the native aster, with several species readily available which will produce dense clusters of snowflake-like flowers on two-to-three foot upright stems starting in late summer and lasting until close to November. White Wood Aster produces a cloud of butterfly-friendly flowers with very small white petals and a yellow centers which will gradually turn reddish-purple.

Blue Wood Aster has even showier flowers ranging from pale blue to violet, and have inner pale yellow disk florets which turn reddish-purple as the flower matures over several months. Both White and Blue Wood Asters naturalize (spread) rapidly in the garden using both seeds and rhizomes.

And because no woodland is complete without ferns, consider adding ferns to fill in empty spaces and provide some interesting texture or structure against which your other wildflowers can shine. Christmas Fern will provide evergreen, leathery fronds, while New York Fern offers both a more delicate array of pale green fronds, and it will also spread rapidly, closing ranks with your other ground covers.

Copyright 2009, Joseph M. Keyser

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