Wednesday, June 25, 2014

the rain garden

First section in the yard was our rain garden.  One of our city requirements was to collect a portion of our impervious surface rain runoff in one of a couple ways.  We choose to create a rain garden in our front yard. The first step was to dig down about 18" to the native clay soil.  

Then we brought in 10 yards of special bio-retention soil to fill the hole.  I took a few days off of work to be able to focus on these next steps.

After moving the rocks into place, we spread a layer of mulch down.  It will take a few years for the plants to fill in.  Meanwhile, I wanted to cut down on weeds.  The idea was to put down the mulch first, then just move it aside when I go to plant.

Next up the river rock.  I wanted to create the look of a stream bed.

The roof water enters at the top of these photos and is absorbed into the soil.  It's designed to have 2-4" of standing water and in the event of a major storm. If the water rises higher, then it will drain into the white pipe at the bottom of the picture which then drains into the street...which then drains into the city storm water.
Always love a garden after a good soak.  The plants I ended up selecting for this first round are: 
  • acorus gramineus variegatus ogon (golden sweet flag)
  • carex 'frosted curls'
  • carex buchahanii 
  • carex glauca (blue sedge)
  • miscanthus sinensis 'dixieland'
  • miscanthus sinensis 'purpurascens' (flame grass)
  • juncus effusus
I also put some lavender in and sedums up in the dryer part.  After getting this in, I have stopped planting now till the fall.  We are about to go into our driest months and while I don't mind watering some, I also don't want to lose any plants. 

The below diagram is from the City of Seattle's drainage requirement that you can download here.

My main resource for creating this was the Rain Garden Handbook for Western Washingon that can be downloaded by clicking on the image below.