With all the rainy days in northwest Florida lately, you’d be forgiven for wondering if your property would be better suited to being one giant pond. More importantly, you may begin to wonder where all that runoff will end up. It will likely flow onto non-permeable surfaces, run to your local storm drain, and ultimately end up in the Gulf of America. That thought may be a little unsettling for most of us, given the amount of pollution that water carries. That certainly is a concern, and if it is one that you share, then follow along as we discuss alternate routing of that water through rain gardens.
What is a rain garden?
Rain gardens use low-lying or sloped areas in your landscape that capture rainwater and funnel it into the local aquifer. They may be built in any shape or design that fits your yard, and planted out with appropriate grasses, perennials, and annuals that don’t mind occasionally having “wet feet”.
Placement
So where should we put these gardens? They’ll need to be at least 10 feet from your foundation and 25 feet from any septic systems. Look for areas in which water collects after rainstorms or those sloped areas where water runs through your property. For the sloped areas, you’ll need to dig out the upslope side and relocate that soil on the downslope side. That’ll create a basin to catch the water and allow infiltration.
How Big
The average size for these gardens is around 100-300 ft2, though needs can vary, and your situation may call for a different size. The idea is that the garden can handle the volume of water passing through the area without flooding. Your soil type will drive this decision. If you’re very sandy, you likely will only need to add some compost to the existing soil. If, however, you have higher clay content, you’ll need to heavily amend the soil. Your goal is to drain approximately 1 inch of water per hour.
Planting it out
To find success with your rain garden, you’ll want to select plants that are well-suited for Florida. The plants you pick will need to sustain themselves through periods of drought and survive flooding during the rainy season. Plant selection will again depend on your individual situation, but there are some common plants to consider.
Black-eyed Susan (Rudbeckia hirta), swamp milkweed (Asclepias incarnata), and canna lily (Canna spp.) are great choices for herbaceous plants.
Fakahatchee grass (Tripsacum dactyloides), and Muhly grass (Muhlenbergia capillaris) are also excellent choices. These are particularly exceptional on the berm created when upslope soil is moved to the downslope side of the rain garden, as they can stabilize soil.
In larger gardens, consider using shrubs and trees. Buttonbush (Cephalanthus occidentalis), and wax myrtle (Morella cerifera) fit this role quite well.
Summing up
Managing stormwater is a crucial aspect of living in Florida. Rain Gardens are an excellent tool in this campaign. With a little planning, you too can transform your landscape into an environmental boon that cleans pollution and recharges your local aquifer. For more information on this and any horticulture topic, contact your local Extension office.
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