Perennials for Moist to Wet Soils

News Article

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 1 or 2 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.
Goats'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 which 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. Other
common names include black cohosh and bugbane.

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 few insect or 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.

Cord grass (Spartina pectinata) is a
native prairie grass. It is a tall, warm-season,
perennial grass which is usually found in wet prairies.
Cord grass normally grows 4 to 6 feet tall, but can
grow up to 10 feet tall in favorable sites. Cord
grass spreads aggressively via underground stems
or rhizomes. Its spreading, aggressive nature
make cord grass a poor choice for small gardens.
However, it can be effectively used on steep banks
and along lakes for erosion control. The leaf blades
of 'Aureo-marginata' have yellow margins.

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 1 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 swamp milkweed (Asclepias
incarnata
), marsh marigold (Caltha
palustris
), crested shield fern (Dryopteris
cristata
), ribbon grass (Phalaris arundinaceae var.
picta
), and globeflower (Trollius
europaeus
).

This article originally appeared in the August 21, 1998 issue, p. 112.

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