Rain Garden Takes Root During Green Week

Plus: A Step-by-Step Guide to Planting Your Own Rain Garden

by Catherine Wachs of Right Brain Design & Jan Feinman of Parks & Trees Com.

(Green Week: April 16, 2008) Editors Preface: The corner of Kane Park at Beach Avenue and the Boston Post Road in Larchmont Village is undergoing a transformation from a little-noticed patch of dull grass to a vibrant, colorful rain garden, thanks to the efforts of the Village of Larchmont Parks & Trees Committee, Department of Public Works, Sheldrake naturalists and a gang of kids who showed up on Wednesday, April 16 during Green Week to help dig dirt and dump gravel so planting can begin on Friday.

The colors in the plan are the bloom colors for the various plants going into the Kane Park Rain Garden.

Catherine Wachs, an environmentalist, designer and community volunteer, worked with Jan Feinman, chair of the Parks and Trees Committee, to research, design and plan the garden. The schedule calls for: digging the drainage, preparing the beds, planting in the spring and fall, and laying a path of pavers that will run through the two sides of the rain garden and on through the park where other developments are underway.

The garden began with a hole dug by the DPW and gravel added for drainage. A crew of kids helped Catherine Wachs amend the soil with compost. Photos by Jane Lipman (above) and Catherine Wachs.

The new rain garden sits on a relatively dry, elevated section of the park. “Everyone asked why not put the rain garden down where it floods,” reported Ms. Wachs. “ but that's not usually the best place.” Flooded areas are wet for a reason – they have poor soil for drainage or are below the water table., she explained. “Planting uphill from the flooded area will divert some of the water away from there.”

That’s the point of a rain garden – to soak up water so it doesn’t run off and create problems.

The point of the Kane Park exercise, however, is not only to improve one corner of Larchmont.

“We chose Kane Park near Beach Avenue for visibility,” said Ms. Wachs. The idea is to encourage those who pass by to plant similar gardens on their own properties – both for their beauty and for their ability to retain storm water. To further their goal of spreading rain gardens throughout the community, Ms. Feinman and Ms. Wachs laid out a step-by-step guide for how – and why – to plant:

Step-By-Step Guide To Building A Rain Garden

What is a Rain Garden?

Rain gardens are shallow, basin-shaped gardens designed to soak up rainwater, mainly from roofs, driveways and patios. Rain gardens look exactly like regular flower gardens, but act as a “living sponge.”

When it rains, a rain garden fills with a few inches of water and allows that water to slowly filter into the ground, but it drains before mosquitoes can breed.

Rain gardens are optimally planted with native, perennial species that provide food and shelter for birds, butterflies and beneficial insects.

How Do Rain Gardens Help?

Roofs, roads, parking lots and other hard surfaces channel rainwater onto the streets and down storm sewers instead of into the soil. This water, tainted by chemicals, oil, pet waste and fertilizers it picks up from lawns and driveways, is discharged into our water, polluting our lakes, streams and drinking water reservoirs.

By capturing this water, rain gardens filter the pollutants and recharge groundwater. Rain gardens help to protect and conserve precious water supplies, while providing hydration for our trees and gardens.

Planting a rain garden may seem like a small step, but when you calculate the amount of rain that runs off your roof, the positive impact becomes clear. A rain garden allows 30% more water to soak into the ground, compared to a patch of lawn.

By capturing rainwater in a rain garden, holding it and then slowly releasing it into the soil, the rush of every rainstorm can be slowed and cleaned – quickly, neatly and naturally.

How to Build a Rain Garden.

Step 1: First determine where you would like to site the rain garden. As long as it’s 10 feet from a structure’s foundation, you can put a rain garden anywhere.

If you are discharging your gutter downspout into the garden, or capturing water from a sump pump, you can determine where the water will flow by spraying a garden hose along the ground to replicate the natural path of where the water flows. This is the optimal place to capture the runoff.

Step 2: If you are capturing roof runoff, the formula for water holding capacity is:
roof square feet divided by 3 = rain garden square feet. That handles 1 inch of rainfall.

Step 3: Test the chosen spot for drainage. Dig a 1 foot hole, fill it with water and see how long it takes to drain. If it doesn’t drain completely after about 6 hours or overnight, you have a high clay content and you will need more sand - about 50-50 soil to sand. You can also add gravel at the deepest level for even greater storage capacity.

With a hose or spray paint, outline the area to be planted. Remove any grass and
dig to a depth of two feet in the center, sloping up gently to form a gradual depression. Then you can amend the soil you dug out (minus grass) with a mix of sand and
compost for drainage.

Step 4: Spread the soil mixture evenly over the bed. Place the plants that like moisture in the deepest part of the bed. Move all the plants around in their pots until you are pleased with the arrangement. Then you can plant. Cover the bed with shredded leaves or mulch.

Care: For the first 2 months, make sure the garden is well watered until the plants become established. Weed frequently, as you have disturbed the soil and activated weed seeds.

For the remainder of the growing season, keep an eye on the garden if you experience drought. Otherwise sit back and enjoy. You’ll soon have gorgeous blooms and an abundance of birds and butterflies.

Good Web Sites to Get You Started:

Rain Garden Network
Healthy Landscapes, University of Rhode Island

Native Plant Center at Westchester Community College
Bronx Botanical Garden

Rain Barrels and More

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