Wednesday, April 6, 2016

It's Water-Wise Wednesday with Frannie the Fish {Rain Gardens}

Spring has sprung! Frannie wants to share a great activity you can do with your troop that will have far-reaching positive impacts for your community and groundwater - installing a rain garden. A rain garden is a garden of native shrubs, perennials, and flowers planted in a small depression, which is generally formed on a natural slope. It is designed to temporarily hold and soak in rain water runoff. Rain gardens help filter out pollutants such as fertilizers, chemicals, bacteria, and others contained in runoff. They also incorporate native vegetation, reducing the need for fertilizers and after the first year, maintenance is usually minimal. Here are just a few of the benefits rain gardens provide:
  1. Improves water quality by filtering out pollutants. Rain gardens are effective in removing up to 90% of nutrients and chemicals and up to 80% of sediments from rainwater runoff.
  2. Allows for 30% more water to soak into the ground than a conventional lawn.
  3. Attracts beneficial birds, butterflies and insects.
  4. It looks great!

Work with your Girl Scout troop and local community to find an appropriate area to install a rain garden. Here are some helpful tips from Frannie to get you started:
  •  Check with your local nursery for a list of rain garden approved native plants. These plants don't require fertilizer, have good root systems, and are better at utilizing water and available nutrients than non-native species.
  • A rain garden should have an area about 20% the size of the roof, patio, or pavement area draining into it.
  • A rain garden should be longer than it is wide and positioned perpendicular to the slope of the land in order to catch the maximum amount of rainfall.
  • The cost of a rain garden is dependent on a lot of factors (soil type, size, types of plants, etc.). But you can expect to pay between $3 and $5 per square foot in plant costs and soil amendments (a soil amendment is something added to alter the properties of the soil, for example, peat moss should be mixed with soil with high levels of clay).
  • Find out more about installing your own rain garden here!

A troop working hard can install a rain garden in an afternoon. Digging the garden is the most time consuming part, as 6-8 inches of soil is typically removed to add amendments. Conduct an infiltration test and a ribbon soil test in preparation for installing your rain garden:

Infiltration Test

Here's what you need:
  • Shovel
  • Water
  • Popsicle stick 
  • Ruler

Here's what you do:
1.  Dig a hole about 6-12 inches deep and at least 4 inches in diameter in the rain garden site (roughly the size of a coffee can). 

2.  Fill the hole with water and let it sit for an hour or two to pre-wet the soils for your test.
3.  Refill the hole with a water and push a popsicle stick into the side of hole to mark the water level.

4.  After an hour, measure and record the depth of the water again. You may want to continue taking measurements at hourly increments for a few more hours.
5.  If the water has dropped 1/2" or more; this is a good site for a rain garden. You still might want to consider soil amendments.
6.  If the water level dropped less than 1/2"; you will have to amend your soil or try another site.

Ribbon Soil Test

Here's what you need:
  • Small measuring cup 
  • Water
  • Ruler

Here's what you do:
1.  Collect a few teaspoons of soil from 4-6" beneath the surface.
2.  Place about 2 teaspoons of soil in the palm of your hand and add drops of water until the soil has reached a consistency that makes it moldable, like moist putty. Knead the soil while you add water.
3.  Form the soil into a ball and place the ball between your thumb and forefinger.

4.  While gently pushing the soil with your thumb, squeeze the soil upward into a strip of uniform thickness and width.

5.  Allow the strip, or ribbon, to emerge and extend over your forefinger until it breaks from its own weight. 
  • If the soil could not remain in a ball form, you have sandy soil.
  • If the soil formed a ribbon less than 1" long before it broke; you have silty soil.
  • If the soil formed a ribbon 1-2" long before it broke; you have slightly clayey soil.
  • If the soil made a ribbon greater than 2" long before it broke, you have highly clayey soil which is not suitable for a rain garden.

6.  Refer to the resources at the bottom of the rain garden page to calculate garden depth, garden size, placement, and plant selection.

Share pictures of your troop installing a rain garden and you could be featured on Frannie's blog!