How To Build A Rain Garden – A Solution For Soggy Wet Areas On Your Property

Dear Casual Gardener,

What the heck is a “Rain Garden”?

Signed, Curious on Country Ridge Road

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Dear Curious,

This is a timely question as we are entering a typical Fall rainy season. It is a good time to get a Rain Garden started, with the intention of completing the process in the Spring.

Do you have a wet spot on your residential or business property? Go with the flow and create a rain garden to help solve the problem. An existing wet spot is the perfect area to place a Rain Garden because it’s the area that naturally accepts a lot of rain water run-off. Fighting against this location and having the water run-off elsewhere might be an unending battle. My suggestion if you have an existing wet area in your yard, is to build a Rain Garden on top of the spot and redirect the water from your roof, home and driveway to the location.

A “Rain Garden” is a man-made depression in the ground. Rain gardens are suitable for any land use situation; residential, commercial and industrial. It is used as a way to improve water run-off while beautifying your landscape. A Rain Garden forms a “bioretention area” by collecting water runoff, storing it, than permitting it to be filtered through and slowly absorbed by the soil. Ultimately, by creating a rain garden you are assisting your community with Stormwater Management.

We suburban homeowners – or anyone for that matter – can creatively recycle all the wasted water which runs off our roofs and landscapes this way. Usually the water gets shuttled to the drain and eventually a river through the stormwater system, then sent off to the ocean. It is much better if we are able to replace the water to the water table after we “filter” it through a Rain Garden. By creating a “Rain Garden” you are truly contributing to the environment in a positive way. It also allows some people to grow beautiful wetland perennials – a magnificent contribution to your community.

Choosing the right place for your rain garden is important. A rain garden is a system of retention pond area, soil, plants and mulch that will retain water and soak it up instead of letting it run off of your property (even though your “pond” will be dry most of the time). So the most basic things are the “pond,” or depression into which water will flow, and the soils that will absorb the water. Each Rain Garden site should be considered unique. Microclimates (light, temperature and wind), and the size of the drainage area will influence the size of the rain garden and plant selection process.

The base layer of a Rain Garden should be a reservoir of gravel at the bottom of the garden bed. You can also add tiles or an under-drain that leads to another area. This will prevent a waterlogged rain garden. The idea is to create a living sponge of soil, plants, roots and mulch, not a soggy bog. Additional components of a Rain Garden include a base mulch/organic layer. It provides for the decomposition of organic material, and also plays an important role in the removal of metals. Shredded hardwood mulch is the preferred choice, since it allows for maximum surface area for binding and resists flotation/wash-out. Mix in planting soil. The best mix is probably organic matter in the form of leaf mulch (20%) blended into a sandy soil (50%) with and about 30% top soil. The planting soil mixture provides a source of water and nutrients for the plants to sustain growth.

A planting design should include species that tolerate extremes. My suggestion is to use native species. You can creatively plant them to be “naturalistic” in design or combine them with grasses and non-native perennials which might be more floral. There will be periods of water inundation and very dry periods, so plant selections must be able to survive all these conditions. Most river bank plant species will do well in rain gardens. The choice of species could include plants that mimic forest habitat and have an aesthetic landscape value such as flowers, berries, interesting leaves or bark. Groundcovers, perennials shrubs and trees can be incorporated into the planting design as well.

So go out there and work on that wet spot in your yard - - fix it by building a Rain Garden!!

For further information on Native Plants and Rain Gardens and how to build them, please contact Jim Kleinwachter of Conservation @ Home, a division of The Conservation Foundation (http://www.theconservationfoundation.org/), at 630-553-0687 x 302.

Jim’s website suggests the Rain Garden Manual  (which can be downloaded here in a PDF format) from The University of Wisconsin Extension Service .

Another good online resource for Rain Garden building with very detailed information is www.raingardens.org or this blog, which also has some marvelous photos - http://bit.ly/1DAjqw.

Special thanks - - The diagram photo above is credited to “The Family Handyman” section on Readers Digest.com and an article by Lucie B. Amundsen. What a great resource! Thank you very much for sharing this diagram with The Casual Gardener readers.

Shawna Coronado says Get Healthy! Get Green! Get Community! www.thecasualgardener.com, The Green Blog - www.gardeningnude.com, or The Garden Blog - http://thecasualgardener.blogspot.com