Continuing Education and
Communication Services
3614 Administrative Services Building
Ames, Iowa 50011-3614
(515) 294-9915
7/16/01
Contacts:
Richard Jauron, Horticulture Extension, (515) 294-1871,
rjauron@iastate.edu
Del Marks, Continuing Education and Communication Services,
(515) 294-9807, dmarks@iastate.edu
Yard and Garden Column for the Week Beginning July 20
Perennials for Moist to Wet Soils
By Richard Jauron
Extension horticulturist
Iowa State University Extension
When selecting perennials, it's important to choose plants that are suitable for the site. Garden sites can vary tremendously. Some areas are hot and dry. Others are wet. Wet sites can be challenging, but they also provide gardening opportunities. The following perennials perform well in moist to wet soils.
Jack-in-the-pulpit (Arisaema triphyllum) is a native woodland wildflower. It is commonly found in moist woodland sites. Jack-in-the-pulpit consists of one or two three-leaflet leaves and a separate flower stalk. The flower structure consists of a club-like spadix (the preacher or "Jack") and the leaf-like spathe (pulpit) which curves up and over the spadix. The spathe may be green, purple-brown or striped. A cluster of berries develops after flowering. These berries turn bright red in fall.
Goat's beard (Aruncus dioicus) is another native woodland wildflower. Goat's beard grows 4 to 6 feet tall and 6 feet wide. Its pinnately compound leaves are 2 to 3 feet long. Dense spikes of creamy white flowers are produced in early summer. Goat's beard performs best in partial shade. In the home landscape, goat's beard is best used as a background plant because of its large size.
The flowers of turtlehead (Chelone species) somewhat resemble a turtle's head. Chelone glabra is native to Iowa and produces white flowers. Chelone lyonii has rose-pink flowers. Both plant species grow 2 to 3 feet tall. Turtlehead prefers moist to wet soils in partial shade.
Black snakeroot (Cimicifuga racemosa) is an erect 4- to 6-foot-tall plant that blooms in mid-summer. The small, white flowers are borne on 2- to 3-foot-long, wand-like flower stalks. Black snakeroot performs best in moist, shady locations. 'Hillside Black Beauty' is a popular variety with coppery purple foliage. Cimicifuga racemosa is also known as black cohosh and bugbane.
Joe-pye weed (Eupatorium maculatum) is a large plant that grows 5 to 6 feet tall. Plants produce large clusters of pinkish purple flowers in late summer. The attractive flowers also provide food (nectar) for monarchs, viceroys and other butterflies. 'Gateway' is a popular variety. Joe-pye weed grows best in partial to full sun.
A tall, spectacular plant of moist prairies is queen-of-the-prairie (Filipendula rubra). It produces large, fluffy flower plumes in June through July. The individual flowers are 1/4 to 1/2 inch in diameter and are peach to pink in color. Plants grow 6 to 8 feet tall. Its large size makes it unsuitable for small gardens. Queen-of-the-prairie performs best in cool, moist, partially shaded locations. 'Venusta' is a widely grown variety with deep pink flowers.
Japanese iris (Iris ensata) flowers in early to mid-summer. The large, flat flowers may be up to 10 inches wide. Numerous cultivars are available. Flower colors include white to blue, purple, reddish purple and lavender-pink. The flowers often have veins, stripes or blotches of a contrasting color. Japanese iris requires moist, acid soils. It grows in partial to full sun. Compared to bearded iris, Japanese iris has fewer insect and disease problems.
Yellow flag (Iris pseudacorus) has sword-shaped leaves and blooms in late spring. The light yellow flowers have brown blotches on their falls. Yellow flag is an excellent plant for wet areas along streams and ponds. It performs best in moist to wet soils in partial shade to full sun. Plants may grow 3 to 4 feet tall when provided ideal growing conditions. In spring, the newly emerged leaves of 'Variegata' have yellow stripes. The variegation gradually disappears by mid-summer.
Native to moist, open woodlands in eastern Iowa, cardinal flower (Lobelia cardinalis) grows 3 to 4 feet tall and produces scarlet flowers in late summer. The colorful flowers are also attractive to hummingbirds. Plants perform best in moist soils and partial shade.
Several species of spiderwort (Tradescantia) are native to Iowa. Plants have grass-like foliage and produce clusters of blue to purple, occasionally white or pink, flowers. Though individual flowers last only one day, spiderworts continue to bloom for several weeks from late spring to mid-summer. Spiderworts are easy to grow. They perform well in full sun to partial shade and moist to wet soils. Several hybrid cultivars are available. These cultivars are better than the native species for landscaping purposes. The native species freely reseed themselves and often become weedy in perennial beds. The cultivated varieties are more restrained.
Other perennials suitable for moist to wet soils include sweet flag (Acorus calamus), swamp milkweed (Asclepias incarnata), marsh marigold (Caltha palustris), crested shield fern (Dryopteris cristata), rose mallow (Hibiscus moscheutos), cinnamon fern (Osmunda cinnamomea), obedient plant (Physostegia virginiana), Celandine poppy (Stylophorum diphyllum) and globeflower (Trollius europaeus).
ml: isugarden
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