By Cindy Gilberg
Recently, on one of our many rainy days, I perused a copy of the Plants of Merit brochure. Curious as to which ones are native to Missouri, I noticed that many natives are also plants that are recommended for moist soils. Despite periodic and brief dry spells, this has been no doubt a wet year for most if not all of our region. By now it is quite evident where there are water issues in the landscape. When you look at a Plants of Merit brochure from Missouri Botanical Garden you will see that those that are native have a notation that indicates they are Missouri native plants.
Swamp white oak (Quercus bicolor) is a handsome, large tree (50-70′ tall) that hails from the lowlands of Missouri’s waterways. It is adaptable to both wet and average conditions as is common with many wetland species. It is happiest with an average soil pH, ranging from 6-7.5 and grows surprisingly fast for an oak. Where water is an issue, this oak is a clear candidate for use as a shade tree. The species’ name refers to its large leaves that are glossy dark green on top with a silvery underside.
Two small-stature trees that love moist soils are also listed – spice bush (Lindera benzoin) and red buckeye (Aesculus pavia). These two are actually listed as large shrubs that can be loosely defined as having a multi-trunk growth habit. There is a fine line between a large shrub and a small tree, and I usually see both of these grown as single trunk specimens with a maximum height of about twelve feet. Both tend to grow in open woodland areas where there is either light shade or periodic shade, though they adapt to full sun with proper moisture and average soil. The spice bush blooms with a lovely chartreuse color in March before the leaves have emerged. Not only are the flowers fragrant but the leaves, when crushed, are as well. If you are trying to attract wildlife to your garden, this one is noted as the larval food for the spicebush butterfly, and the rich, red fruit that ripens in fall is popular with many birds. The red buckeye grows naturally in wooded lowlands and along streams where the soil is rich in organic matter. Full panicles of large red tubular flowers make their show in April to May, offering an open invitation to hungry hummingbirds. Its large palmate leaves add a unique texture to the garden.
Another shrub that thrives in wet soil is buttonbush (Cephalanthus occidentalis). This is definitely a multi-stemmed shrub that forms large clumps in full to part sun situations. It was June the first time I saw its unusual, round white flowers, and they were covered with hundreds of pollinating insects, from native bees and wasps to numerous species of butterflies – quite fascinating to see! Buttonbush averages about 8-10 feet in height and can be pruned in early spring to shape or remove the older stems to rejuvenate it.
There are a couple of perennials from the Plants of Merit list that you can add to fill the ground layer. Cardinal flower (Lobelia cardinalis) is a well-known and popular perennial that blooms a brilliant siren red in late summer, beginning about the first part of August. Late summer and fall bloomers are always welcome in any garden and this 3-4 foot tall perennial thrives in moist soils. Hummingbirds, always on the look-out, find their way to cardinal flower instantly. The other from the list is soft rush (Juncus effusus), a tall, graceful grasslike plant that is a perfect textural complement to all of the above plants. It is a common sight along Missouri rivers and streams and in most flood plains. The 3-4 ft. long leaves make perfect perches for dragonflies that rest between feasting on mosquitoes and other small insects in the garden.
So don’t distress when you see water sitting on or moving through your property. This is just a small sampling of those plants that can help you solve water issues while allowing you to have an attractive garden as well.
If you would like a more complete list of plants that grow in wet conditions, visit the Shaw Nature Reserve website and view Chapter 2 – Rain Gardens of the Native Landscaping Manual online.
Cindy Gilberg, horticulturist and Missouri native, founded and ran the garden center at Gilberg Perennial Farms with her husband Doug for 28 years, also teaching classes and workshops on gardening and garden design. She now focuses on garden design, consulting and teaching, and also works part-time in the Whitmire Wildflower Garden at Shaw Nature Reserve, emphasizing the use of native plants in home landscaping.