Rain Gardens

Cutting the curb allows more runoff from the street to soak into the rain garden. photo courtesy of thecoves.ca

A rain garden is a depression in the landscape planted with native plantings that allows rainwater to runoff of impervious surfaces such as roofs, driveways, walkways, parking lots and even compacted lawns and gives it an opportunity to soak into the ground rather than into the stormwater systems.

Do areas of your landscape collect water? With spring season rainfall, you may notice the low spots in your landscape where water flows naturally.  Turn those undesirable low spaces into functional and beautiful rain gardens. Rain gardens are a great way to beautify an unsightly area and reduce the amount of stormwater runoff. Designed with native plants, these gardens break up soil, filter water from impervious surfaces, and replenish our depleting ground water supply. If a low spot does not occur naturally, create one and place in between areas where run off occurs; eliminating much of the water in its path from reaching the storm water collection systems.

Rain gardens are beneficial for many reasons including erosion control, improving water quality by cutting down on pollutants and local flooding, and replenishing our diminishing groundwater supply. Stormwater runoff contributes to 70% of the pollutants in our local waters. Rain gardening is an environmentally friendly and attractive way to optimize rainfall.

Start by determining the right location for the new garden. It is important to avoid utilities and septic tanks, stay at least 10 feet from the house (to prevent infiltration from seeping into the foundation of a home), and avoid existing trees. Changing the soil level near a tree’s roots can cause it to die. Test the soil to see how well it drains and determine how it will need to be amending.  A rain garden should have a filtration rate of 1” an hour. A balance of topsoil, sand, compost and mulch will result in the best filtration system. Consider adding a few rain gardens to your landscape and directing all the rainwater from your roof to the gardens through underground piping. If you use rain barrels, use rain gardens as a location for your rainwater overflow.

Calculate the size of your garden and consider where you will direct water from; a well-drained rain garden will require being 20 to 30% of the impervious area you are collecting. The poorer the soil quality the larger the garden needs to be so amending is the best bet. If the soil is very compacted and heavy, the rain garden will function properly by excavating and amending soil and adding an underground drainage system with gravel and perforated pipe allowing excess water to permeate. Any rain garden is better than not one at all, so if your landscape only allows for a small garden, any little bit helps!

After preparing your garden, make sure to select a variety of native plantings to meet the sun exposure and water requirements of your location. A rain garden is comprised of three zones; wet, wet-dry and dry. The use of native plantings for rain gardening is important because of their tolerance to the local climate and soil and water conditions. Native plants have extensive root systems enabling them to improve water filtration and soil conditions. Native plants do not require fertilizer and once established will require little maintenance.

courtesy of elkhorn.unl.edu

Rain garden designs differ from retention basins in a sense that they infiltrate water within a day or two; eliminating stagnant water and mosquito breeding. Not only are they extremely functional gardens but also beautiful spaces encouraging butterflies, birds and beneficial insects to visit your landscape. A beautiful rain garden will absorb 30% more water than a traditional patch of lawn! A small garden goes a long way in terms of eliminating a portion of runoff from reaching storm drains. Create a few gardens or direct more water to the garden and build a larger rain garden that is unique to your home and property layout. An environmentally friendly landscape design company can assist you with the perfect design layout for your home. If you live in northern Illinois or southern Wisconsin, contact Crimson Valley today for a consultation. We would be thrilled to advise and install the proper eco-friendly rain garden for your home.