However, heavy rain does not have to be as big a problem as we’ve designed it to be. Typically, there are four ways water can disappear:
- Evaporation off of surfaces
- Absorption into trees and plants
- Percolation into the soil
- Conveyance as runoff through streets and drains
We don’t have to limit ourselves to just the 4th option. If we allow places for water to sit and move slowly, we reduce the chance of it ending up somewhere we don’t want it. So instead of “fast” and “away”, we should look at water as “here” to “stay”, at least for a little while.
You can do this in your own yard or neighborhood by building a rain garden or a bioswale. They help slow down and filter water using the first three water disappearing tricks listed above. Plus, they also add aesthetic benefits to your home, inviting birds and butterflies to visit.
What's the difference between a rain garden and a bioswale?
Bioswale: a ditch associated with or connecting other stormwater infrastructure that has been planted with native plants. These tend to exist along property edges, by roads, or along rights of way.
Photo credit: Sarasota County and the Sarasota Bay Estuary Program
How do I build a rain garden or bioswale?
STEP 1: Find a location that makes sense for your yard or neighborhood. Is there a spot in your backyard that tends to collect water more than others? Is it in an area you can get to easily in case you need to pull weeds or do some upkeep? Then you may have a good location for a rain garden or bioswale. If your great spot is part of a Sarasota County right of way, that’s ok too! You can get a Right of Way Use Permit, which is $150. County staff can help walk you through the process. Call 941-861- NEST (6378).
STEP 2: Know what’s below the ground. You don’t want to accidentally dig into any buried utilities. Call 811 or 1-800-432-4770 (early in the week if you are planning weekend yard work) and let them know where you are planning to dig. They will notify your local utility who will send someone out in 2 – 3 days to mark where your utility lines are. Although your lines will probably be deeper than where you plan to dig, it’s always a good idea to double check.
STEP 3: Figure out size and slope. Each bioswale and rain garden will be different. There are a lot of factors that go into how much water these features will hold and how fast that water will flow through, percolate, evaporate, or be absorbed by the plants. Things like the type of soil (percolation), the slope of the surrounding area area (how fast and how much water runs through the area), the amount of sun (evaporation) all play a role. Mollie Holland, with the Sarasota County NEST Program, has example templates you can use and can offer guidance specific to your location (call 941-861-5000). In the meantime, here are a couple general guidelines to get you started:
- You want rainwater to enter a rain garden slowly to be most effective.
- Rain gardens are typically be 4-8 inches deep (max 18 inches) with all sod removed and soil loosened to allow for percolation. Plan for one end to be the lower end and one end to be the upper end, so water can still drain out.
- After planting your plants, it’s common to mulch a rain garden to help water capture and avoid erosion.
- Bioswales often allow for more water to flow through than rain gardens, especially during larger storm events. This can be achieved by creating a central flow channel using rock or wetland plants, and planting on either side if the central channel with other aquatic plants, grasses, or ground covers.
- Since bioswales tend to handle more flow than rain gardens, it is recommended to plant 1-2 feet wide strips at the top of the swale bank on either side to help minimize erosion as the other plants are getting established.
STEP 3: Pick your plants. Rain gardens and bioswales need plants that can withstand dry and wet conditions. Using a variety of Florida native plants helps with the overall function and beauty of the rain garden or bioswale. You will probably also notice butterflies and birds using the area! Here are some great options: