Regional Gardening Reports :: National Gardening Association

In the Garden:
Southwestern Deserts
September, 2011
Regional Report

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Wildflowers, grasses, and boulders create this naturalistic rain garden that blends with its surroundings.

Rain Gardens

Rain gardens in the desert? Absolutely! Although other regions of the country may have a head start on the concept, rain gardens are gaining popularity in the arid Southwest. A rain garden is a shallow depression where water can pool briefly while it percolates through the soil. It is planted with suitable vegetation that can take advantage of a brief influx of rainwater. Wherever you live, native plants are typically the best choice because they are acclimated to natural rain patterns and can still thrive when the garden dries out between showers. Rain gardens can also help recharge groundwater supplies and act as biofilters of on-site pollutants, such as oil or other chemicals that wash off driveways.

Consider these elements when planning to add a rain garden to your landscape:

Good soil drainage is key to a successful rain garden. Water should penetrate the soil within 24 hours. It is important not to have standing water, which allows mosquitoes to breed. Also, overly wet soil promotes root rot and not many desert plants tolerate wet feet. Try this quick method to determine drainage: Dig holes 6 inches deep and wide in various locations you are considering. Fill with water. Wait 4 hours and measure how much water has drained. Multiply that number by 6 to obtain the percolation rate for 24 hours. Soil drainage at the rate of 1 inch per hour is considered excellent.

Catchment Options
Impervious surfaces such as rooftops, driveways, and sidewalks capture considerable runoff. Rain gutters are a great way to direct water to a rain garden. Also use natural contours, drainage paths, dry streambeds, and depressions in your landscape to direct and pool the water. The surface area of a rain garden can vary to suit your needs. Generally, they are about 6 inches deep, and no deeper than 12 inches.

Manmade Structures
Keep rain gardens 10 feet away from building foundations and 25 feet from septic systems. A gentle slope of 4 to 12 percent will carry water away from a structure towards the rain garden. (Steep slopes require more time for infiltration.)

Final Warning: Utility Lines!
Dial 811 to be connected to your state Blue Stake. This free service will advise you about underground utility lines. No sense planning a garden where you won't be able to dig!

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