Step-By-Step Sustainability: How (And Why) To Make a Rain Garden

Step-By-Step Sustainability: How (And Why) To Make a Rain Garden

  • “Step By Step Sustainability,” written by Kane County Resource Management Coordinator Jessica Mino, focuses on ways Kane County residents can move toward a sustainable, future-friendly lifestyle. Each article will help you take that next step toward sustainability, with topics ranging from household products to managing your outdoor spaces to travel to work life.

This month we will be heading outdoors to explore how to enhance an eco-friendly yard while dealing with (and protecting) all the stormwater we have had with during the wettest spring on record!

My Stormwater Management System

At my home, our gutters are connected to a rain barrel that first captures as much water as possible from a rain event. This allows me to have the water I need in my yard/garden without drawing from other freshwater supplies like groundwater.

The gutters then discharge to vegetated areas or the new rain garden we installed this year.

The new rain garden captures the water that my rain barrel cannot hold, allowing as much water as possible to infiltrate back into the ground, remaining in the water cycle it was intended to and minimizing the impact from my home.

Instead of being rushed to a storm drain that shoots the water out directly to a river (causing flooding and pollution), the water falling on my yard has time to soak back into the ground, replenishing groundwater supplies, not exacerbating flooding issues, and being filtered by the soil to keep human impacts out of the nearby rivers.

How I Built My Rain Garden

Step 1: Lay Out The Footprint

First, lay out the size and shape of your rain garden using string or a hose.

Next, excavate to the necessary depth.

Ours was 9 inches below the level line. Make sure that the bottom of the excavated rain garden is level so that you do not end up with pooling water in a particular area.

You can do this by tying string to stakes around the perimeter, leveling these strings, and then making sure the excavated depth is exactly 9 inches below that leveling line across the entire area.

If you have clayey soils like I do (and many people in our area), put in a layer of sand (about 2 inches) to help with drainage and water storage below ground.

Step 2: Backfill With Soil

Backfill with soil amended with sand and compost to promote infiltration.

If the back of the rain garden is slightly lower than the front, you will want to create a berm on the low end to ensure that stormwater has time to infiltrate without just running out the low end. Unlike the rest of the rain garden, compact the berm so that it remains stable.

We plan to plant native species that tolerate drier conditions on the berm to ensure this area blends in well with the rest of the landscaping.

Step 3: Install a Footpath

You want to make sure the soil does not compact so be careful not to walk on your rain garden!

To access the center of the rain garden for planting and maintenance, install a foot path. This way, your steps will be concentrated to just those areas and the remainder of your rain garden will remain porous.

Step 4: Fill In With Native Plants

Finally, the fun part! Fill with native plants that are appropriate for moist conditions and sun or part-shade depending on the location of your rain garden. (The stakes mark where I have planted seeds or root balls that are waiting to sprout!)

Then cover with hardwood mulch. It is important to have hardwood mulch so that it doesn’t float away.

Step 5: Install an Overflow

Make sure to install an overflow for rains that exceed the capacity that your rain garden is able to intake. Reinforce with rock to prevent erosion.

Refer to the Rain Garden Manual for further information about how to install an overflow and other rain garden details.

Our current rain garden is only half of the planned final area. We will be doubling this size in the fall when we have more time and native plants can be transplanted again.

3 Common Mistakes

  1. Putting it where there is already standing water. Wrong! If there is standing water in a location, that most likely indicates the soils do not quickly drain there. Choose a different spot where the soils have better drainage, possibly up-flow of the wet location to minimize the amount of water that ends up where you have standing water.
  2. Directing water to soil without amending it. Wrong! Not all gardens are rain gardens. To be a rain garden, the soils need to be somewhat sandy AND not compact. This step is really what promotes infiltration and prevents runoff.
  3. Planting ornamental plants instead of native plants. Wrong! Yes, the amended soils allow for faster infiltration, but the deep roots of the native plants also help with this. As the roots push deep into the soil, they continue to create avenues for water to reach deep within the earth. The deep native roots also uptake a significant amount of additional water, further reducing stormwater issues. The best part is that native plants need minimal maintenance and almost no watering after a year or two of extra attention when first getting established.

Check Out The Kane County Rain Garden!

Check out the Kane County rain garden that comes up and grows happily on its own with minimal maintenance each year.

For more information on constructing a rain garden, check out the University of Wisconsin-Extension Rain Garden Manual.

Rain gardens are an excellent way to deal with the immense amount of rain we have gotten while promoting environmental stewardship. Thanks for taking another step toward sustainability with us!

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