How to Build a Rain Garden in Ten Steps
Here are some basic steps to give you a good start building your own rain garden
Rain Garden Information Packets are available.
The packet includes 3 laminated, 2-sided, color sheets with
How To Build a Rain Garden, Maintenance Instructions and Plant Selection Guide.
Step #1 – Find a location
The rule of thumb suggests that you place the garden at least 10 feet away from your home to prevent flooding in your house. Do not locate the garden over a septic field. You should try to choose a naturally occurring low spot in your yard or position the garden where your downspouts or sump pump outlet can be used to direct rainwater into your garden. Try to choose a location in the sun either full or partial.
Step #2 – Measure drainage area
If you are building the rain garden in a low spot in your yard you do not need to measure the
drainage area. Just ensure the area receives water regularly during a rainstorm.
If you are capturing water from a roof or other hard surface you will need to measure the specific drainage area of that surface and multiply by the number associated with the type of soil you have. For sandy soil multiply by 20%, for loam use 30-35% and for clay use 45-60%. These numbers are somewhat inflated but they will ensure the garden holds as much water as possible.
Step #3 – Create a design
Whether your garden is large or small the same basic principles apply. By planning your garden on paper first, you will be able to create the best appearance possible for your rain garden.
Step #4 – Choose your plants
Native plants are suggested for rain garden installations because they are best adapted for our climate. You will want to choose plants (flowers and grasses) that will grow well in both wet and dry areas because the rain garden will temporarily fill with rainwater from time to time.
Step #5 – Lay out the garden
Lay out the shape and boundary of the garden based on your design.
Before you start digging contact your local (usually non-profit) organization that locates underground utilities.
Step #6 – Dig the garden
Remove the turf grass and dig your garden approximately 4-8 inches deep. Use the soil to build a berm around the garden edges if necessary.
Step #7 – Prepare the soil
Amend the soil with 2″-3″ of compost. Mix in well.
Step #8 – Plant the flowers and grasses
Follow the design you created and place your plants in the approximate positions. Step back and look at the garden and the design. Plants should be placed about 1 foot apart from each other. Once you are satisfied you can start planting the flowers and grasses using a hand trowel.
Step #9 – Mulch the garden
Use coarse, fibrous, shredded wood chips that won’t float or blow away. Apply the mulch about 2-3 inches deep. This will help to keep the moisture in and the weeds out. Avoid cypress mulch because it is made by chopping down rare, old-growth cypress in wetlands.
Step #10 – Water and arrange downspouts
After you have planted the garden water every other day for 2 weeks if it doesn’t rain until garden looks to be growing on its own. Good water techniques and maintenance is the key to a quality rain garden.
Remember: Call before you dig! (underground utilities)