As the climate keeps changing, we must be prepared for different types of weather. We need to adapt our landscape to support the surface areas around us. One way to help is by planning a rain garden.
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What is a rain garden?
A rain garden is a shallow depression in a yard that can allow storm water to pool. Often during heavy rains, the water moves so quickly that it doesn’t have a chance to soak in the ground. A rain garden will allow the water to slow down and pool so plants can benefit. These gardens are beneficial to the environment helping to recharge the aquifer, support wildlife and filter out toxins before water can pollute streams. In a properly built rain garden the water will infiltrate through the material before mosquitoes have a chance to breed.
History of stormwater
Historically storm water management has meant getting water off-site as quickly as possible. Gutters and pipes would quickly move water off hard surfaces into local streams, ponds, and rivers. Unfortunately, this quick movement has meant that for decades our local water has been getting polluted with all sorts of harmful toxins from our hard surfaces.
Why plant a rain garden
Hard surfaces like roofs and roads are a host to grease, oil, sediment, and heavy metals. It also can contain bacteria and harmful components from pet wastes. All these components and sediment fill creeks and streams. Heavy rainfall contains 70% of the pollution that flows into water ways.
Whatever goes into a catch basin will travel to creeks and streams untreated. These untreated pollutants cause suffocation of fish and plants that need light and oxygen to live. Losing aquatic life causes stagnant, unsightly, and sometimes foul-smelling water.
By planting a rain garden, you can help to reduce the amount of pollutants that enter local waterways. You will also be improving the environment.
Fun fact: One inch of rain on 100 square feet of surface
will result in 60 gallons of water!
Advantages & Disadvantages
Advantages
- They can be easy to retrofit
- You can design it to fit a small space, there is flexibility so you can fit it into any landscape design.
- When planning a landscape, it can provide an attractive feature that can help to improve open spaces.
- Can reduce rate of run off, a rain garden soaks up 30% more water than lawns.
- Easy to maintain, as with any garden space weeding and some maintenance will be required.
- You will be providing a wildlife habitat. Choosing native plants will attract beneficial native insects.
Disadvantages
- As they are often small, their impact on volume reduction can be limited
- Although the work shouldn’t be too much it does require landscaping and management
- If it has not been planned out appropriately, they can be susceptible to clogging if surrounding landscape is not managed well.
- If you live on property with steep slopes a rain garden will not work.
Planning your Rain Garden
Depending on where you live planning a rain garden could be as simple as diverting roof run-off to an area with that already has plants and you can add a few more. If you are like me and live in a desert climate you will have to put a bit more thought into you rain garden.
If you have good sandy soil that drains freely make a garden a little larger, but a good baseline is a bed that is 20 to 30% the size of your roof or driveway. Your basin should be 10 feet away from the foundation of your house and in a downhill direction. **Make sure you are not going near your septic system.
If you have an area that already collects standing water, make sure you are choosing a low spot that allows water to drain within a day or two after a storm.
To do a soil test – dig a hole about 10 inches deep and fill it with water, if the water drains within 48 hours this is good.
Once you have dug your area up replace the heavy soil with one half sand, one quarter compost and one quarter topsoil. This will create a fast draining mixture to add you plants to.
Use the extra soil and some stone to create a berm on the side away from your home to create bowl where the water can pool.
If you need to assist the flow from your house to the newly created rain garden you can dig a shallow trench, 3 to 4 inches deep, leading from the downspout to the garden. Line this with landscape fabric and cover with stone to create a streambed effect.
Plants for a rain garden
A rain garden needs to have plants that can tolerate periods of temporary saturation and periods of drier soil.
Make sure you reach out to your local extension office for a list of native plants for your area. For your plant layout you need to consider native plants that can tolerate wet feet (roots) in the center, moving out from that place plants that can tolerate occasional standing water and then on the outer edges plants that prefer drier soil.
Some plants to consider depending you your climate are:
- A dogwood tree – these flowering trees provide blossoms in the springtime but have colorful stems which provide interest in the wintertime as well.
- Rhododendrons are a good cold hardy native to consider.
- Pink turtlehead – this is a trouble-free perennial that doesn’t mind wet feet. Late summer to early fall blooms, grows in zones 3-8, you can use several plants
- Wild columbines are an important source of nectar for hummingbirds and butterflies so will attract pollinators to your yard. They produce bicolor red and yellow blossoms in late spring.
- Meadow anemone is a deer resistant salt tolerant perennial that has white blossoms.
- Butterfly weed can provide some color as well as being an important larval food for monarch butterflies.
There are several other plants to consider. Read my article about 11 Easy Plants for the First Time Gardener.
