Front Yard Makeover — Native Plant Edition: Digging for Me, Lots of Rain Garden Info and Resources for You

Now that the retaining wall was up, it was time to dig in and get ugly.

In almost every project there’s an ugly phase, where the project area looks like a huge hot mess. This is when I second-guess every decision I made. Being a front yard project, I was extra worried about this. The anxiety fueled my work as I put my head down and dug in.

First I laid sheet mulch (cardboard) over the areas in and around the retaining wall that wouldn’t be de-turfed or contoured. As anyone who has laid out a kiddie pool in the yard knows, it takes about two weeks to fully smother turf. But cardboard takes about 3-6 months to fully decompose. It does a great job of getting rid of grass while feeding the microbes it’s yummy cardboard-hydrates.

Then I de-turfed the conveyance trench and the rain garden area and sent the turf, grass side down, on to the cardboard areas. I dug out the rain garden and carted the displaced soil behind the retaining wall to level the ground there, and up near to the house.

Then I raked it smooth. (Is it just me or is raking out piles soothing to everyone?)

Next came contours in the rain garden. It’s on a slope, so I wanted a deep area, then some terraces that would be drier, yet allow wicking action and a bit of an over flow area. I also plan to tap into our gutter-to-street drainage to add a pipe for overflow drainage. Rule #1 for Water Harvesting: Plan for overflow. That will be added later, before we divert our roof gutter to the trench.

The following day, I beat the soil from the turf slabs and transported it to a pile in the backyard. When I’m done with this project, I’ll cover it over with a tarp and let the grass die and rot down. Then I’ll distribute the reclaimed soil to my in-ground beds giving them a bit of an elevation gain.

How to Build a Rain Garden:

1. Plan for overflow. (I’m putting in a vertical pipe that will tie into our gutter drainage system.)
2. Test soil infiltration rate. (See this video from Tualatin SWCD)
3. Calculate area necessary to drain portion of roof served by your gutter.
   • Go to Google Maps and look up your address.
   • Right-click to bring up the Measure Distance tool.
   • Get dimensions of your roof area that is drained by the downspout you wish to have serve your rain garden. (Do not worry about roof-slope, think footprint.)
   • Formula: Roof Area to Drain x 10% = Rain Garden Area
   • I had just under 500 sq feet, so I made ours 50 sq feet. But since there is slope and the soil is slightly heavy, I went deep and added contours to add volume to what the garden can handle before overflowing to drainage.
4. Add plants that can handle lots of water and drought. Sounds weird but a lot of our natives are really good at this. I got these from Sparrowhawk Native Plants Nursery:
   • Foothill Sedge (8″ tall x 18″ wide at maturity)
   • Dense Sedge (18″ tall x 18″ wide)
   • Spreading Rush (1-2′ tall x 1-3′ wide)
   • Common Rush (3′ tall x 1-2′ wide)
   • Oregon Iris (15″ tall x 2″ wide)
   • Blue Eyed Grass (10″ tall x 10″ wide)
   • Red Columbine (3′ tall x 1-2′ wide)
   • Elegant Calico Flower ( 1′ x 1′)
   • Lupine (4′ tall x 2′-3′ wide)
   • Douglas Spirea ( 2′-6′ tall x 2-3′ wide)
   • False Lily of the Valley (1′ tall x 2-3 wide)

Whaat? That’s a lot of plants for 50 square feet, Amy–are you sure they’ll fit?

Good point! I like to over plant, because some aren’t going to make it. Also some of the sedges and rushes will live in the conveyance trench and others will be placed elsewhere in the landscape. I like to have options.

If you are interested in adding more native plants, consider joining the Backyard Habitat program. You’ll get a coupon pack for local nurseries that will recoup the membership fee, which at this time is $30.

Rain Garden Resources

• Oregon.Gov Oregon Smart Guide: Rainwater Harvesting
• Oregon Rain Harvesting Company
• Tualatin SWCD Video: How to Build a Rain Garden | Urban Conservation
• OSU Extension: Rain Garden Downloads
• PortlandOregon.Gov: How to Manage Stormwater: Rain Gardens

Are you doing any rainwater harvesting? If so please share your ideas!

Front Yard Native Plant Makeover Article Series

1. Retaining Wall Complete 
2. Digging for Me, Lots of Rain Garden Resources for You
3. Moving Mountains of Mulch 
4. Nine Steps to Planting A Tree (Vine Maple)
5. How to Plant Perennials so They Can Thrive