(Editor's Note: This article was originally published on August 12, 2010. Your comments are welcome, but please be aware that authors of previously published articles may not be able to respond to your questions or comments.)
When a garden needs a big, bold shrub, call on giant fleeceflower (Persicaria polymorpha) with its large white sprays of flowers and dark green, deeply veined foliage. This massive herbaceous shrub is also known as Polygonum polymorphum, but whatever you call it, this is one specimen that will make a statement in the landscape. The showy flowers and seed heads attract both birds and butterflies, but will not appeal to deer. The dark green coarse foliage is an excellent backdrop for more delicate medium size plants, and the nodding flowers give movement to a garden space.
Giant fleeceflower grows well in clay soil, is hardy in zones 1 through 11, and thrives in full sun; however, mature plants will tolerate a little shade and some drought. The flowers look like astilbe, only on a much larger scale, nodding in the breeze atop 6 foot stems; they have no fragrance. The shrub will spread from 6 to 10 feet in a clumping habit, and reach 4 to 7 feet in height. Be aware that this is a fast-growing species, so make provisions to keep it corralled where you want it to stay by sinking metal or plastic boundaries in the soil as far out as you are willing to let the plant spread. Bloom time is June and the flowers continue through summer. At the end of the season, the flowers turn reddish-brown just like astilbe. This provides a nice textural addition to the fall garden landscape.
Persicaria grows from rhizomes or stolons and, therefore, can be invasive if not controlled; it dies back in the winter. The plant prefers moist soil, but will still grow in dry conditions, though not as profusely. Propagation is by division in spring or fall, or by seed started in a cold frame in early spring. Japanese beetles, slugs, snails, and aphids are fond of this shrub and will need control.
TOXICITY NOTE: All parts of the plant can cause skin irritation in sensitive people. If ingested, all plant parts will cause stomach upset.
Yellow wax bells (Kirengeshoma palmata) is another little used perennial for shady situations. This lovely plant is native to Japan and Korea in the mountains; it does well in zones 5 to 8, with hardiness to -20F. It must have shade to grow, and is a wonderful addition to woodland gardens and shady beds and borders.
Kirengeshoma is a late blooming perennial, coming into flower in late August and early September, a nice addition to a garden that may already be fading. Though slow-growing, the plant can grow quite tall - 3 to 6 feet, and the clumps spread up to 3 feet. Glossy maple-leaf shaped leaves reach 4 to 8 inches long and provide a beautiful background for the drooping yellow waxy blossoms that are shaped like badminton shuttlecocks.
Plant in rich, moist soil that is acidic, and shelter the plants from wind. Water regularly and do not allow the soil to dry out. When new growth begins in spring, propagate by division. Be careful not to damage any of the new shoots. Slugs and snails will feast on the tender new growth of yellow wax bells, but deer will not.
Photos from Wikimedia Commons (GDCL) on Wikipedia.