How I Made A Rain Garden

No, not rainforest garden, rain garden!  I've finally finished the plantings and laid the topsoil, mulch and marble chips, and all thats left to do in this spot is wait for the plants to fill in. 

I used a groundcover of liriope "big blue" (the big clumping kind) and liriope spicata (the short and spreading kind) to create a patchwork of different heights.  Cordyline australis "red star" and "dark star" rise out of the liriope at alternating heights, and dyckia "red planet" sits on the edge of the rocks.

This is the driest and sunniest part of the yard, and I'm tired of water runoff running down my sidewalk and driveway and doing my garden no good.  If wasting water wasn't bad enough, fertilizer and pesticides wash away with the rainwater too, polluting our rivers and contributing to deadly algal blooms in the St. Johns river.  A rain garden is just what the doctor ordered here.

Here's how to make a rain garden. 

Choose Your Site.
I carefully chose a site that has well draining soil and is at a distance from the house's foundation.  By placing it in front of the patio, I'm intercepting all the water that falls on the concrete and letting it naturally drain into the soil where the garden needs it most. 

Test Your Soil
If there's a lot of clay, you may want to take steps in improving the drainage, by making the swale wider or by inserting drainage pipes, for example.

Choose Your Plants.
The plants should be real workhorses, and able to tolerate drought as well as inundation depending on how wet it gets.  Ideally your plants will also help to control erosion, especially if this is a problem in your area.

Excavate a Swale.
A swale is where the water collects during rain.  It should always drain away from the house, and water shouldn't be allowed to collect either, as algae and mosquitoes can be a problem.  This might work for larger rain gardens, but not in a small residential setting.  I recommend giving the ditch a pleasing curving shape.

Plant and Mulch.
It helps to add some moisture retentive topsoil or compost, so the rainwater can be soaked up.  Be sure to add plantings at the foot of your rain garden, to prevent water from vacating too quickly!  You can use theme you like: I opted for a simplistic one. 

Lay the Rocks.
Smooth rocks are the best, since they appear natural and don't interlock and get compacted like the jagged rocks.  I used jagged white marble chips anyways, but only after determining the fast drainage of the sand beneath.  What can I say?  I can't afford the good stuff, and thats okay.  Two bags did the trick for mine, and you can always add more later if you didn't add enough.  Try to keep the rocks thicker on the edges to keep the look of a natural creek bed.

Water Heavily.
This helps to establish the plants, washes dust off the rocks and helps to ensure that the garden drains properly.  After watering the plants, fill the swale with water to the rim and make sure it drains quickly.  If it puddles for too long, you can always help the drainage along.  Insert wide pvc pipes vertically in the center, capping with metal mesh to discourage mulch and rocks from building up.

The rocks catch rainwater and let it slowly seep into the ground instead of into the gutter.  They also double as a pleasing and natural path!  I planted a dyckia "red planet" on the edge, and it will spread out into the white rocks, adding interest and breaking up the straight lines.  Planting along or inside the swale makes it look more natural.  Here's a closeup of the dyckia.

Notice how I've continued the stream bed from the lower right hand corner of the image, where rocks are filled in between the concrete. 

I'll probably add some more liriope as groundcover until they fill in, and ad some more rocks against the patio for a more natural curve... I'll keep you posted!