What is a Rain Garden?
A garden that encourages stormwater runoff from rooftops, driveways, roads and parking lots to soak into the ground.
The garden acts like a "sponge" and filters out pollutants picked up by stormwater (fertilizers, pesticides, antifreeze, pet droppings, etc), cleaning the water before it enters our local creeks, rivers and lakes
It is wise to use native plants in your rain garden because they have deep roots and promote a diverse and healthy microbial population in the soil that can then break down nasty toxins
Monroe County Incentive Program
- Apply for incentive
- Schedule site visit with County Stormwater staff
- Create rain garden
- Verify installation
- $1 per square foot (10 inches of compost amended soil) (up to $200)
- Provide receipts
- More information to come. If you have any questions please contact Dana Wilkinson at 812-349-2960
Build Your Own Rain Garden
Sizing and Location of the Garden
- The guideline is to measure rooftop and driveway area draining to the garden and divide by 10. The logic behind this is for every one inch of runoff volume, one half can be absorbed by the rain garden
- Generally between 50 and 150 square feet. Less area is okay, but soil amendment (adding compost or sand, removing clay) to increase infiltration becomes more important
- Rain gardens should be located at least 10 feet from the house, on a gentle slope that catches water. You want to encourage temporary water ponding, this can be done with a berm, wall or depression
- Identify the drainage pattern of your property and put the rain garden in a position the receive runoff from roof and the driveway. Do not place over septic fields or utilities. Sunny areas are best and away from large trees if possible
- Placement of the garden is essential to its success.
- Fall or spring work best for construction. Advantageous to have an observation period before planting
- For the construction phase you want to first locate utilities.
- Remove existing sod (can reuse in berm and garden). You could kill the existing sod with newspaper, black plastic or herbicide.
- Dig out the area and remove the existing clay soil - to a depth of about 10 inches.
- Create a berm with overflow away from the house. Install a border. Direct downspout water to garden.
- Backfill with "fluffy" soil - compost. Put in plants. Add double shredded hardwood mulch.
- Native plants are the best to use. Rain Garden Plant Guide is a guide to native plants appropriate to rain gardens in central and southern Indiana.
- Homeowner's Rain Garden Manual goes into detail about how to plant a rain garden. Also, the Rain Garden Design for Home Owners is a good link.
Native Plants for Rain Gardens
- Native plants improve soil health because they are deep rooted and do not require the use of fertilizers or insecticides. They provide nectar, seeds, berries and leaves that attract local wildlife - such as song birds, butterflies and bees.
- In your garden, space the plants about 1 to 2 feet apart
- Be aware of which species spread and self seed
- Inter space flowering perennials with sedges and grasses to improve root structure
- Use plugs, as opposed to seeds
- Plants that can tolerate floods, droughts, rabbits and deer are best
- Consider grouping plants. This simplifies weeding
- Annuals can be used to add color
- Ask at local garden stores for native plant availability. The Indiana Native Plant and Wildflower Society (INPAWS) has great resources on Indiana's native plants, including landscape-worthy Indiana natives and a list of nurseries and garden centers in Indiana that have native plants
Cost Saving Strategies
- Buy plugs wholesale
- Start plants from seed in trays, then transplant to rain garden
- Start your own composting pile (combination of leaf litter and grass clippings) to later add to soil amendments
- Dig in your garden and skip the gym membership
Rain Garden Photos
Students at Batchelor Middle School install a rain garden.
The ground is prepared for a residential rain garden in Monroe County.
The same garden with native Indiana plants in bloom.
Runoff from the parking lot at the Monroe County Highway Garage prior to rain garden installation.
The same area of the Highway Garage property after rain garden installation.
The Highway Garage rain garden in bloom.