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08/04/2016 12:01 AMIt’s hot, it’s dry. Do you know where your sedum is?
These tough plants are the quintessential ingredient in many green roofs, where they stoically withstand sun, wind, drought, and more, but still offer attractive blossoms as well as leaf colors. Any plant so brave surely has potential in other landscape battle zones.
You may know sedum as the tall autumn species that flowers along with mums and ornamental kale in doorstep planters. But several dozen sedum varieties grow low and spread wide, some of them capable of living on pure gravel, some pert and colorful through the winter. Most sedums abhor wet feet. Some refuse to grow in rich, fertile soil. In other words, they are the very definition of great landscape problem-solvers.
For more detailed information, I turned to a book by expert Brent Horvath, The Plant Lover’s Guide to Sedum (Timber Press, 2014).
Horvath explains that the term “sedum” is both a genus of plants and a widely-used generic term for relatives of the true sedums. These “succulents” store water in leaves. They are cousins in the botanical family Crassulaceae, along with the stalwart jade houseplant.
Horvath offers lists of sedums for shade, as well as for ultra-dry conditions, rock gardens, terraces and walkways, terrariums, living wreaths, green walls, and, of course, green roofs. He also offers a great deal of advice on how to design with sedums, including color groups and non-sedum companion plants.
Horvath’s beautifully illustrated book covers 150 varieties, but for species that thrive in southern New England, I asked two long-time garden center owners for ideas.
Teri Smith, owner of Smith’s Acres in Niantic, recommends ‘John Creech’ sedum (S. spurium), one of the toughest mat-forming plants of its kind. This fast-growing creeper grows only three to four inches high, but a single plant can cover two square feet. ‘John Creech’ is a close relative of another toughie, ‘Fuldaglut’ or ‘Fireglow’ sedum (S. spurium).
Both plants are extremely drought tolerant, once established. Smith reminds us, however, “All plants—without exception—need regular water while the roots become established during the first season.”
Nancy DuBrule-Clemente, owner of Natureworks in Northford, offers a number of favorites.
“‘Angelina’ sedum (S. rupestre) is an amazing plant and you can walk on it for
sure,” she says. “Other sedums that can handle a few footsteps include Russian sedum (S. kamtschaticum) and ‘Blue Spruce’ sedum (S. rupestre, a.k.a. S. reflexum).
“Among non-walkable sedum groundcovers, I love Sedum ‘Bertram Anderson’,” she adds.
DuBrule-Clemente often uses spring-blooming woodland stonecrop (S. ternatum ‘Larinem Park’) for dry shade in her landscape designs. According to Brent Horvath’s book, other shade-tolerant sedums include stolon stonecrop (S. stoloniferus) and gold moss (S. acre).
Woodland stonecrop is one of a very few eastern native sedums, which raises an interesting dilemma. If you are trying to use more native plants to support native pollinators, few sedums make the list. I find only two others in commercial trade, a tall variety called Allegheny stonecrop (S. telephioides) and groundcover sea star (Sedum pulchella).
Luckily, many native flowering plants grow beautifully in sedum beds. Yarrow, purple hyssop, penstemon, and asters, for example, all enjoy the same habitat.
Want to see sedum and other groundcovers under extreme conditions? Visit a green roof. There’s a two-thirds acre roof at Whitney Water Purification Facility, 935 Whitney Avenue, Hamden. UConn’s Storrs campus has green roofs at Gant Plaza and Storrs Hall. The Ocean House at Watch Hill, RI, has a green roof framed by a magnificent ocean view.
To learn more about the sedums and other plants that succeed in roof projects, see the delightful book, Small Green Roofs (Timber Press, 2011).
Bottom line: If you have areas where lawn grass or other plants refuse to grow, you may find a willing landscape partner in ground-covering sedum plants.
Kathy Connolly is a landscape designer and horticulture consultant from Old Saybrook. Reach her through her website, www.SpeakingofLandscapes.com.