Rain Garden
Your Quick Guide to Green

A rain garden is not only good for the land, it can be fun, too. By allowing the rain at your home to soak into the ground in your lawn, you help the environment. For me, it might just be a good excuse to grow more Iris.

Reducing runoff protects our natural resources. It helps to recharge natural water supplies and protects your area from flooding. Plus, given a little 'design flare', it can be a great enhancement to your garden and benefit wildlife.

Mosquitoes? Don't worry about it. There are gardens that are designed to hold water, but this is not one of them. Yours should allow water to soak into the ground within a few hours.

Location

Plan your garden at least 10' from the house. You don't want to have water soak in near your foundation.

Find a flat area for your rain garden. This is because the rain will need to have a chance to soak in -- a steep slope will just give you run off. When you've got the right area, you can create a low berm around it so the water won't escape. A typical depth is from 3" to 8".

Below a downspout? Sure! Your home downspouts are great for rainwater gardens. You can direct your downspout with an buried extension or a swale. Again, make sure it is at least ten feet from the house.

Remember, don't put your rain garden over your septic system or sewer lateral. You also don't want to place it in an area that is already wet -- if it's a wet area, it's not draining well enough.

Also, it's not recommended that you build it under a large tree. Trees' root systems draw a lot of water. The roots also might get damaged.

Size

The size of your rainwater garden is determined by two things: your home and your soil. You can calculate the square footage of runoff from your roof. Measure the length and width of your house. Then, multiply the square footage according to what type of soil you have and how far away your rain garden is from the house.

When you look at your home, how much of your roof runoff runs through your downspout? If your home is roughly 40'x50', your home square footage is 2000 square feet. If 1/4 or 25% of that runs through one downspout, multiply 2000 by 0.25 and your answer is 500 square feet of runoff through one downspout.

The location is important. If it's closer to the house, it should be larger. This is because you'll want to make sure it soaks into the ground faster. If it soaks in slower, it could be bad for your home. If it is further than 30' away, it could be smaller. Some of the rain will soak in before it gets to your garden.

Now, if you live in the Eau Claire, Wisconsin area, your soil very well could be sandy or sandy loam. If you've situated it away from your home (further than 30'), it can be smaller. If you're in Rice Lake, have clay soil and it's closer to the house, your garden should be larger.

Unsure about your soil? Dig a hole about 8 inches deep and fill it with water. If it still has water after 24 hours, it's not going to work. You want a garden, not a pool.