Q: Our backyard has very low spots where the water ends up after heavy rains. How do I deal with this? I would like to plant a garden of shrubs and perennials but don’t think many can take that much water. Red maples and birch seem happy, but the hydrangeas I planted last year all died. It gets quite a bit of sun.
Answer: Most plants will not tolerate sitting in standing water or saturated, soggy soil for long periods. You may be able to add one to two inches of soil to fill in low spots or raise the grade enough so that water will run off better or at least not accumulate there. A steep grade is not necessary or desirable because in dry years you do want the water to sink into the soil and down to plant roots.
You may have a good location for a rain garden. Many plants love this environment — some stunning natives in particular, such as button bush and clethra. (Both are also butterfly magnets!) Take a look at the University of Maryland Extension webpage on stormwater practices.
Don’t get bogged down (no pun intended!) with details. Just plant what likes “wet feet.” Native plants are the best. For more plant choices, look at the U.S. Fish & Wildlife Service’s excellent publication, “Native Plants for Wildlife Habitat and Conservation Landscaping: Chesapeake Bay Watershed.” In the lists, ‘Plants for Freshwater Wetlands and Other Wet Sites’ should be helpful. (There is also the equivalent online database, http://www.nativeplantcenter.net/.).
You may not have standing water continuously in the future. However, it is predicted that we can expect a lot more wet years and extreme weather ahead because of climate change. A rain garden is a smart way to handle this, as long as this spot does not hold water all summer (and breed mosquitoes). When you install a rain garden, the plant roots will be pulling in the water and drying up the low area, too.
By Ellen Nibali, Horticulturist, University of Maryland Extension Home and Garden Information Center. Ellen writes the Garden Q&A for The Baltimore Sun.