By Cindy Gilberg
There is something magical and magnetic about a water garden that adds new dimensions to the pleasure of being in the garden. You can create your own natural oasis, reminiscent of some of Missouri’s most beautiful aquatic habitats, with the addition of native wetland plants. The plants described here are excellent, hardy choices with great ornamental qualities that can be real show stoppers for water gardens.
Just as grasses are an integral part of our prairies, so sedges (Carex sp.) are to our natural wetlands. There are more Carex species in Missouri than any other genus. However, for small to medium size water gardens it is best to stick to those that don’t spread rapidly. Gracefully arching, grass-like leaves soften the edges of the water garden, and the interesting, persistent seed heads are an added feature. The most unique seed heads appear on Carex grayii, round and spiky at the same time and resembling the also unique hairdos of some rock music enthusiasts. The palm sedge (C. muskingumensis) has distinctive foliage that radiates from the arching stems. Try also the tussock sedge (C. stricta) with its clumping habit that is similar to many of the smaller ornamental grasses. All of those mentioned here tend to be clump-forming, grow 1 to 3 feet tall and are well-behaved for use in a garden setting.
A six-foot wonder is thalia, sometimes called hardy canna (Thalia dealbata), native to the southeastern (bootheel) part of Missouri. Large, canna-like leaves give it a more tropical appearance. Its foliage makes it a great choice for adding impact amongst plantings of grass-like plants such as rushes. Most intriguing are the tall flower spikes that bear pendulous purple flowers in mid to late summer.
Water plantain (Alisma triviale) is a lesser known plant that deserves a place in our water gardens. Large, rounded leaves provide a light green foil for the airy white flower sprays that arrive on the scene in mid to late summer. I have deadheaded the flower stems and been rewarded with even more of the baby’s breath-like flowers, extending its bloom time into fall. This is another one whose foliage is valuable when designing good textural combinations with fine textured or grasslike plants.
The most significant feature of rose mallow (Hibiscus) is its large, showy flowers that appear in late summer. Hardy hibiscus is no stranger to gardeners with all the hybrids that have been introduced, but many may be surprised to think of them as wetland plants. There are two species that are native to Missouri, H. lasiocarpus and H. laevis (formerly H. militaris). Both of these put on a grand display of elegant white or pink flowers. I suggest a tip pruning after the first flush of growth to promote a more branched and shorter growth habit. Even with this method, they will attain a height of about 5 feet. Create a stunning combination by planting hibiscus with cardinal flower and some sedges or rushes.
Red is a commanding color in the landscape and the cardinal flower (Lobelia cardinalis) provides that blast of color in late summer and early fall. Its flowering corresponds to the increased feeding activity of hummingbirds that fight over the rights to its nectar. Standing tall (2-3 feet), this native is one that tolerates shade and still puts on a good show.
If part to full shade is an issue for you in choosing plants for your water garden, try adding some of the wetland ferns. They add a lushness to the scene that is soothing and cooling – a plus on a hot summer day. Native ferns thrive with wet ‘feet’, not submerged, so be sure to situate them in more shallow water where they receive afternoon shade. Some classic choices include the ostrich fern (Matteuccia struthiopteris), royal fern (Osmunda regalis) and cinnamon fern (Osmunda cinnamomea). All are about 3 feet tall and bear spectacular chocolate to cinnamon colored spore fronds.
These native plants are not fussy and will put on a commendable performance with little care. Explore the possibilities for your water garden and be sure to find a place for some of these gems. Ask for them at your local independent garden center.
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.