When choosing plants for a rain garden you have to consider not only light conditions but the moisture content of the soil. Rain gardens can have parts with 1. shallow water most of the time, 2.wet soil that occasionally has standing water, 3. moist but not wet soil, and 4. dry, well-drained soils. There are few grasses that grow well in shallow water but there are several that tolerate or do well in wet soil. Notice that most of the grasses described below tolerate wet conditions rather than prefer them.
American Mannagrass (Glyceria grandis)
American mannagrass is a cool weather perennial that grows across much of the US ecept the Deep South. It lives in wet sites such as bogs, streams, marshes, ponds, and wet ditches. The flowers and seeds are carried in loose airy panicles six to sixteen inches long. Provides food for waterfowl.
Height: 3-5’
Bloom Time: Mid-summer
Light: Full sun
Soil: Wet soil, standing water
Hardiness: Zones 3-8
Blue Joint Reed Grass (Calamagrostis canadensis)
Native to marshes, wet prairies, and open woods of the throughout most of the US, this clump forming cool-season grass has floppy leaves and nodding spikes of purplish flowers four to ten inches long in early summer. Spreads rapidly by shallow rhizomes.
Height: 3-6’
Bloom Time: Early summer
Light: Full sun to light shade
Soil: Wet to moist
Hardiness: Zones 3-7
Vanilla Sweet Grass (Hierochloe odorata)
An aromatic perennial, vanilla sweet grass is native to the northern states of the US including Alaska where it is found in wetlands, prairies, and savannas in wet to medium moist soils. The leaves are up to thirty-nine inches long and grow horizontally because they lack stiff stems. Plants spread by rhizomes and can be invasive.
Height: 10-24”
Bloom Time: April to June
Light: Sun; tolerates part shade
Soil: Prefers moist but tolerates wet.
Hardiness: Zones 3-8
Prairie Cord Grass (Spartina pectinata)
This tough warm season grass was one of the original components of the tall grass prairie. It is native to the northern states of the US where it grows in low-lying, moist areas or on the margins of ponds and rivers. Plants form dense arching clumps and bear one sided spikes of flowers in mid-summer Although the flowers are not showy the foliage turns bright yellow in fall and remains attractive all winter.
Height: 3-6’
Bloom Time: Mid-summer
Light: Full sun but tolerates some shade.
Soil: Moist to wet
Hardiness: Zones 4-9
Indian Grass (Sorghastrum nutans)
A native of eastern and central US, Indian grass is one of the components of the tall grass prairies and one most beautiful ornamental grasses. It is a warm weather perennial, with erect blue-green foliage that turns yellow ten burnt orange in the fall. Flowering spikes appear in late summer on stiff stems and are two to three feet above the foliage. Although Indian grass prefers rich, medium moist soil in full sun it tolerates wet conditions, some shade, and infertile soil.
Height: 3-5
Bloom Time: Late summer
Light: Full sun; tolerates some shade
Soil: Prefers moist to dry but tolerates wet.
Hardiness: Zones 4-9
Virgina Wild Rye (Elymus virginicus)
Virginia wildrye is a cool season perennial bunchgrass found in the eastern two thirds of the US where it grows in bottomlands, stream banks, and various disturbed sites. In addition to being a palatable to crops it is attractive in the garden and in arrangements. Its flower are carried in spikes six inches long and are carried on stems up to four feet long well above the clump forming foliage of narrow leaves.
Height: 3-4’
Bloom Time: June to October
Light: Full sun to part shade
Soil: Prefers moist, tolerates wet and dry.
Hardiness: Zones 3-8
Switch Grass (Panicum virgatum)
Switch grass is a warm weather perennial native to North America where it was once a component of the tall grass prairie. It has a stiff upright form, showy flowers carried in airy panicles, and attractive fall color. The flowers emerge reddish to silvery in mid- summer and persist into winter. The leaves turn varies shades of yellow in fall.
Height: 4-7’
Bloom Time: Mid-summer
Light: Full sun but tolerates some shade.
Soil: Prefers moist to wet, tolerates dry
Hardiness: Zones 5-9