Do you have a low, soggy area in your lawn? A spot that is a giant puddle after a rain? Take this liability and make it your greatest asset—create a “rain garden” here, replete with moisture-loving flowers. I call this theme, Wet and Wild. Rain gardens are shallow, bowl-shaped depressions filled with plants. They are normally at the base of a hill or anywhere where water collects. These gardens accomplish their task by soaking up as much as 30 percent more water than conventional lawns, and they filter out pollutants from rainwater runoff. The flowers planted in these soggy sites also create a natural habitat for birds, butterflies, and other helpful insects.
To create a rain garden, start by digging out a basin in a naturally low, wet spot. It can be any size you want, but it must be at least 4 to 8 inches deep. Mound the excavated soil and stones on the downhill side of the depression to act as a dam of sorts. This prevents water from overflowing. The low mound is actually a plant bed, and so it should be wide and not too steep. Do not seed any lawn here. If your soil is heavy and does not drain, mix in some compost to lighten it up. It is important for the soil to contain organic matter, because a rain garden is like a living sponge of soil, fungi, and roots.
Plant the lowest, wettest part of the basin with perennials and shrubs that tolerate “wet feet” such as blue flag iris (Iris versicolor), Little Rocket ligularia, white turtlehead (Chelone glabra), or swamp milkweed (Asclepias incarnata). Around this, on upper areas, use plants that like regular moisture, such as New England aster (Symphyotrichum novae-angliae), blue false indigo (Baptisia australis), and boltonia (Boltonia asteroides). At the outside edge of the basin, place plants that prefer drier soil.
A few native perennial flowers to use in moist situations include Culver’s root (Veronicastrum virginicum), great blue lobelia (Lobelia siphilitica), and eastern blue-eyed grass (Sisyrinchium atlanticum). Consider adding sedges, rushes, and ferns for diversity but also to create a thick root system that a functioning rain garden needs. A great source for rain garden information is the Rain Garden Alliance (raingardenalliance.org).
Marsh marigold (Caltha palustris) is a moisture-loving native flower in the buttercup family. It grows along streams and in wet woods. It is a mounded perennial with clusters of bright yellow flowers that appear in mid–late spring. Marsh marigold is known for its glossy, rounded heart-shaped leaves. It grows in full sun to part shade, and grows 1 to 2 feet tall. Hardy in zones 3–7.
Creeping thyme (Thymus serpyllum) is a somewhat woody, very low-growing perennial. It forms a mat of foliage 2 to 3 inches tall, which spreads over time by rooting stems. When it is stepped on, it perfumes the air. You can plant it among stepping stones, as shown here. Also called mother-of-thyme, it is densely flowering, with deep pink to purple flowers that appear in summer on short stems. Bees love its tiny flowers, and the honey they make from thyme blossoms is aromatic. Creeping thyme has cultivars with dark green, lime-green, or variegated foliage. It grows in full sun and tolerates drought and dry, shallow soil. Zones 4–8.
Low-growing common violets (Viola sororia), with their heart-shaped leaves, is a native found throughout eastern North America. It is very easy to grow as a ground cover under shrubs or larger perennials. In spring, it is covered with small purple flowers that serve as an early nectar source for pollinators. Violets thrive in cool, moist, shady conditions but also tolerate drought. It forms colonies and spreads by seed or short rhizomes. Try the cheerful cultivar ‘Freckles’ (Viola sororia ‘Freckles’) with its white flowers speckled with deep China blue. Flowers are edible! The leaves and stems of violets are rich in vitamins A and C. Zones 3–9.
‘Scentsation’ honeysuckle (Lonicera periclymenum ‘Scentsation’) is an extremely fragrant vining honeysuckle with showy yellow flowers that bloom from mid-spring to late summer. The flowers are followed by bright red berries. ‘Scentsation’ grows to 10 to 15 feet tall, and it is not invasive like other honeysuckles. Full sun. Zones 4–9.