Are you ready to create your own rain garden? The following design elements should be considered when planning your rain garden. Check out the resources for more detailed information as you consider each step in creating an effective, functioning and beautiful rain garden. Learn about UD’s Lewes Campus Rain Garden, why and how it was created by watching this video story, then follow the four steps below to create your own.
Things to consider:
- Step 1. Location and Site Preparation
- Step 2. Garden Design and Plants
- Step 3. Construction of the Garden – Equipment, Permits, etc.
- Step 4. Garden Maintenance
NOTE: You can keep your garden green and growing by connecting a rain barrel to a downspout that will drain into your garden.
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 Developpment Center, analyze and inventory your site or North Carolina State University
- North Carolina State University, Bio Retention Areas, Designing Rain Garden
- For information on soil testing, contact your County Cooperative Extension Office
Determine the planting zone you are in for plant hardiness and geographic location, this will help you select the right plants for your region. Will the garden be in a sunny or shady spot? What would you like to attract to your garden? Butterflies, birds?
- Choose your Plants
- For best results, select native plants suitable for the geography and site specific conditions of your rain garden
- Select a variety of native, flowers, ferns, grasses, shrubs and small trees that will provide color and interest throughout the season
- Group the plants together for the most impact, and estimate one small plant per square foot.
- Select plants can also provide food and habitat for birds, butterflies and bees.
- Resources for Garden Design and Plants
- The following websites and publications offer a range of garden designs and templates, taking in consideration geographic location and site specific conditions (coastal, piedmont, sun, shade).
- There are also garden designs featuring plant materials that will attract birds and butterflies to further enhance your enjoyment! Native, non-invasive plants are encouraged as they are best suited for local climate and site characteristics.
- Design Templates
- Native Plant Resources
- Helpful Tools – Need help figuring out what size your rain garden should be, how many plants you need and how much mulch to buy? Check out these links to help you make those decisions
- Build and Plant Your Rain Garden
- Are you ready to construct your Rain Garden? You determined the size, shape and location.
You tested the soil and determined it has adequate drainage, know how to amend the soil to allow the rain garden to both evaporate and slowly drain rain waters.
- Will you need only shovels and strong backs? Depending on your design and site preparation needs, a roto-tiller or larger equipment may be required.
- Volunteers needing to fulfill scout or school service projects may be ready and willing to assist if you’re doing a rain garden for a school, church, or town building!
- Ready, Set, Go!
- Lay out a rope or garden hose in the shape desired as a guide for digging.Dig the garden; the depth of the depression may vary from 4 to 8”.
- Create the “saucer” contour of the garden. For best infiltration, the bottom of the garden should be level. On a slope, the soil from digging may be used to create a berm on the downhill side.
- Introduce and gravel, peat, sand, etc, that are needed to give proper drainage
- Install your rain barrel, or create swale to direct water into the garden from a downspout or pavement
- Like any new planting, the rain garden may need watering for the first few weeks.During the first season, some extra watering, thinning and replacement plants will also be needed.
- Below is a graphic illustration of the elements of a constructed rain garden.
- Resources for Building Your Rain Garden
- For more detailed information on the actual construction of a rain garden, please visit the following sites:Pennsylvania Stormwater Best Management Practices Manual Chapter 6, Section 6.4.5 Rain Garden/Bioretention, pp. 52
- University of Wisconsin Extension Service’s Rain Gardens: A How-to Manual for Homeowners pp: 11-16
- Low Impact Development Center’s Rain Garden Construction and Sequence of Construction
- West Michigan Rain Gardens, Saving the Great Lakes One Garden at a Time
- North Carolina Cooperative Extension, Building a Backyard Rain Garden
- Rain Gardens are Easy to Maintain but are not Maintenance Free
- More maintenance will be needed during the first two or three years to remove weeds and replace plants that did not survive.
- Mulch annually to keep soil moist and allow easy infiltration of rain water
Rain gardens should be re-mulched with 2-3 inches of mulch every spring. Use a natural, un-dyed mulch.
- Minimize sediment flow into the garden
If construction is still underway on your property or adjacent properties, wait until the soil in the area is planted and stabilized before constructing your garden Sediment in a rain garden can decrease runoff infiltration, and also kill plants.
- Weed, prune, and water your garden, especially during the first season
Newly planted species may have a tough time competing with weeds. The plants in your rain garden will need to be watered regularly during establishment to ensure healthy growth.
- Keep your garden healthy and clean
Rain gardens should be periodically cleared of dead vegetation and any debris that may collect. Replanting may be necessary over time. If a plant is not doing so well in one location of the garden, you may want to relocate the plant to a wetter or dryer area.
- Resources Rain Garden Maintenance
- North Carolina State University: Bioretention Performance, Design, Construction,and Maintenance
- Rain Gardens: A How-to Manual for Homeowners pp: 16-17