Step 1: Locate and Prepare the Site
The first step in planning your rain garden is to calculate the size you will need to offset the stormwater run-off from your roof, driveway and other paved surfaces on your property. The resources listed below will help you determine the size and best location for your rain garden!
First step, choose a location!
Pick a site for your garden that tends to collect water or where runoff from your driveway or downspout can be diverted into it. Your rain garden should be at least 10 feet away from building foundations, underground utilities, and septic system drainfields.
Measure your Garden
A typical home rain garden ranges from 100 to 300 square feet and often captures the runoff from one downspout, or about one-fourth of the rooftop area. For a better estimate, The Virginia ‘s Department of Forestry’s publication Virginia’s Department of Forestry, Rain Gardens, a technical guide pp: 10-13 can walk you through a calculation based on pervious and impervious surface area.If you don’t have room for one larger garden, you may consider planting more than one smaller garden.
Check the Drainage
It is important that your rain garden drains quickly. If drainage is poor, compacted or clay soil may need to be removed and gravel added. The ideal soil is a mix of two parts sand, one part topsoil (no clay), and one part compost. Loosen the soil to a depth of 2 feet.
Resources for Rain Garden Site Preparation
- Determine the size of your rain garden using the appropriate calculations.
- Check out: University of Wisconsin Extension Service’s Rain Gardens: A How-to Manual for Homeowners
- Virginia’s Department of Forestry, Rain Gardens, a technical guide
- Low Impact Development Center, analyze and inventory your site or North Carolina State University
- North Carolina State University, Bio Retention Areas, Designing Rain Garden