Horses for Rain Gardens in Puget Sound

Rain gardens are a bright new idea for dealing with two frequent issues for horse properties: excess runoff and MUD!

A rain garden can be a multi-purpose solution in helping to make both your place and the environment just a little bit cleaner. Most cities and urban areas have realized that more plants are needed to drink up all the storm water that pollutes our recreational and drinking water bodies - old practices just aren’t working with surges in development. On a smaller scale, sacrifice areas, arenas, buildings and take away from plant habitat too, and can contribute to flooding, drainage, and horse health issues. Rain gardens can be a beautiful solution to prevent run-off of livestock manure and urine and can help provide your animals a drier environment.

If you are a horse person and you’ve never heard of a rain garden - you’re likely not alone! A rain garden is a planted, shallow depression in the ground that captures and filters the rainwater that rushes from our barns, houses, driveways, and roads. Rain gardens are planted with native and ornamental plants which help break down pollutants such as nutrients from manure, soap, pesticides from agriculture or petro chemicals from roadways. Rain gardens cut down on erosion and mud, reduce the amount of pollution reaching creeks and streams, recharge groundwater and can be an attractive landscape feature. Plus, they supply a bit of habitat for native insects and small animals like birds and amphibians.

A rain garden isn’t meant to hold water for more than 72 hours so don’t worry about it breeding mosquitoes or creating other problems. In fact, a well-planned and maintained rain garden attracts birds and insects that control pest populations such as mosquitos. It may seem like a small thing, but many rain gardens together (as in neighborhood clusters) help clean up dirty water and slow the flow of runoff reaching Puget Sound. There is a huge movement to install rain gardens all over the Puget Sound region to try and curb the amount of pollutants leaving homes, farms, and businesses. 

Think back to wintertime flows and where wet areas accumulated. Is there a gutter and downspout depositing rainwater into a high-traffic area? Perhaps this water could be channeled into a rain garden.

Native plants are often used in rain gardens. These are the plants that grow in the area naturally, their advantages include:

  • They are better adapted to local climate and soil conditions
  • They are more resistant to diseases and pests—a bonus for you because you won’t need pesticides, fertilizers, or extra water to help them along.
  • Native plants are what local wildlife and pollinating native insects are attracted to.

However, although native plants provide an advantage as far as maintenance, they can also grow quickly in the moist but well-drained rain garden. Dwarf ornamentals, grasses, and even edible plants can be used to provide variety and color, especially in the spring and summer. For specific plant types, choose those that don’t mind getting their feet wet. Pacific Northwest species to consider are red osier dogwood, black twinberry, salmonberry, pacific ninebark, along with rushes and sedges. Plan for drier conditions along the upper edges of your rain garden, and don’t be afraid to add some year-round color or interest in these areas by adding a few ornamentals and edibles. You might even want to add yard art, a hollowed out stump as a nurse log (photos below), or a bird bath or two.  Remember to fence your animals away from the rain garden so they don’t nibble on plants or compact soils which would breakdown its function as a filtration system. 

Once you decide a rain garden would help with your run-off issues, look for resources in your area. It’s important to work with a professional trained in designing a rain garden. They will assess your property and design the garden to factor in the topography of the site, the amount of water it may accumulate, the resonance time needed to filter the water slowly into the ground, and your plant preferences. Local conservation districts, WSU Extension personal, and professional consultants will be able to help with design and installation. In most cases, a downspout from your barn or arena roof will be diverted to the rain garden. Surface water can also factor into the amount of water entering the rain garden.

Once the site is dug, a special rain garden soil mix suited to filtering water is added to the bottom of the rain garden. Many landscape and compost companies now carry this special mix. Various zones in the depression will be planted based on plant needs and water accumulation.

Zone 1, the lowest area, will be well-suited for Dagger-leaf rush, dwarf red-twig dogwood and Henderson’s checker-mallow.

Zone 2, higher up in the depression, can be planted with Daylily, giant camas and columbine (pictured), dwarf tall Oregon grape, Boxwood honeysuckle and dwarf red-twig dogwood.

Zone 3, at the top of the bank, is suited for Ornamental grasses, Ocean spray, red-flowering currant, dwarf strawberry tree and snowberry. (see the Rain Garden Handbook for Western Washington for more plant and design ideas).

There are other ways that owners of farms and ranches can help protect their watersheds and limit the amount of polluted runoff leaving their property. These can include the use of cisterns and rain barrels to capture and reuse clean rain water, natural yard care, limiting impervious surfaces and adding bio-filtration swales. Protecting wetlands, creeks and streams will help fish and wildlife, as well as help, protect Puget Sound. Natural non-chemical pest control is another great practice to sustainably control insects - think bat houses, violet green swallow next boxes and providing a variety of habitat with rain gardens and hedgerows.

For specific help on how to design and install a rain garden, contact your local Conservation District.

Other resources include:  Western Washington Rain Garden Handbook

Rain gardens can:

  • Reduce flooding
  • Reduce mud and erosion
  • Filter polluted runoff
  • Recharge groundwater
  • Provide wildlife habitat – particularly for native pollinators
  • Provide attractive, low-cost landscaping which you may even be able to incorporate into your trail course as a water feature!

Support for this publication was provided by Snohomish County Surface Water Management and the Puget Sound Stewardship and Mitigation Fund, a grant-making fund created by the Puget Soundkeeper Alliance and administered by the Rose Foundation for Communities and the Environment.