Soil with 'poor drainage' can be a plus for gardeners
Does your landscape have areas that retain water? I find it interesting that we use terms like “poor drainage” and often assume that this is a negative in the landscape, and should be corrected. Certainly there are many plants that cannot tolerate “wet feet,” but a drive through any wetland tells you there are many plants that can.
In fact, today’s trend toward a more sustainable landscape has initiated new ideas on managing water movement. Old ideas are to get that water moved off the property, pronto! We use gutters, pipes and drainage tiles to shunt it downslope, where it becomes the problem for the people that live down from us, so they shunt it quickly further downhill, and so on. Gaining volume and speed, the building momentum of the water becomes a factor in erosion, pollution, even flooding.
As our knowledge grows of how large-scale wetlands contribute to soil and water quality, these concepts gradually permeate landscape designs in urban and suburban settings. Containment systems are developed to slow and retain the water from rainfall events, allowing it to percolate slowly down through the soil, refreshing aquifers while being filtered and cleansed in the process.
Every little bit helps and so began the community efforts to establish rain gardens. Rather than drain that wet area in the landscape, it could become part of the healing network by using plants that tolerate or even prefer soggy settings. Many are lovely species, so it does not have to mean a sacrifice in aesthetics.
That said, most rain gardens I’ve seen are not particularly appealing. Plant choices aside, just putting a group of water-tolerant plants in a large depression in the ground has no relation to the larger design. It appears to be just plopped there.
I began to look for those designs that were using the rain garden concepts in a more coherent and artistic application…and they are there. I’ve seen one that perches water in a series of terraces down the side of a house toward the back yard where the terraces broaden and curve until they become the sweeping boundary for the back border.
I was wowed by one that took a more geometric approach. The depression took the form of an ample moat that divided the back yard, spanned with a rustic foot bridge. It was planted with ferns, cardinal flower and common bald cypress. I would want it for my landscape even if it didn’t have such a worthy function.
Not every wet site in the landscape is the right place for a rain garden, and there are certainly times that you may need or choose to change the drainage patterns that exist to suit the larger intention. Just don’t assume that is the only solution.
Carol Reese is ornamental horticulture specialist for the Western District of the University of Tennessee Extension Service.