Landscaping the Back Yard

Our smallish back yard, dominated by shade from a neighbor’s huge burr oak, has endured a number of attempts at landscaping over the years. Early on, I planted various ornamental trees around the perimeter: crabapple, redbud, serviceberry, arbor vitae, white pine. I dug in hostas, Epimedium and wild ginger behind the garage and mostly left them on their own. The grass yard space got progressively smaller as I increased the size of mulched shade beds at the borders.

A few years ago we added a water feature (limestone fountain with river rocks) next to the patio, surrounded by hostas. Then the columnar white pines on the south edge finally succumbed to disease and we removed them, resulting in new sunlight and a set of raised beds. But the rest of the back yard was still a bit of a mess, and every rainstorm resulted in a washed out lawn and, often, a small temporary lake at the bottom of the yard.

A Dry Stream Bed

I wanted to solve the water issue with a rain garden to capture excess water, using deep rooted perennials to let the water dissipate into the subsoil. But rain gardens do better in sun than shade, so I was persuaded to go with another solution: a dry stream bed together with French drains (deep holes into the subsoil filled in with rocks) to speed the percolation of water. Dan Van Weelden from Country Landscapes completed the design last fall, we signed off, and the project was completed over 3 days this spring.

The new dry bed is a deep, gravel-filled cut in the soil, lined with medium to large boulders and snaking around to the back of the yard where the French drains are dug. A second ‘fork’ originates behind the garage and goes to the same place. Large limestone slabs bridge the stream at several points where paths intersect.

The dry stream appears to originate at the rock fountain, but that’s a just a visual ruse — it actually is engineered to take in storm runoff flowing down from the patio path, and it hurries the water along to the cachement area at the back of the yard.

Some of the soil removed during dry bed construction was used to raise the central lawn and level it out, with sod and some flagstone paths completing the look.

Aside from the artfully placed stones, the landscapers added some shade-tolerant plants in and around the dry stream bed: Siberian iris, sedges, and some striking native shrubs: summersweet (Clethra alnifolia) and bush honeysuckle (Diervilla rivularis).

I upgraded and rearranged some of the surrounding beds and borders, using divisions from my hosta collection plus a few new ones. The result is a reasonably harmonious display of greens, blue-greens and yellows amongst the rocky surfaces of the stream bed and paths. We are pleased with the results and were happy to open the garden to visitors for the 2019 Beaverdale Garden Walk.

At the first rainstorm, we rushed out to watch the stream bed at work! As can be seen from the photos below, it does its job very nicely. Water from a 1-inch storm fills the cachement about half full, and water dissipates overnight. I expect that with a huge deluge (3 or 4 inches) we would get some overflow, but that’s probably unavoidable without converting the entire back yard to a cachement.

Rainscaping

During the garden tour we spoke to a number of area homeowners who are also dealing with water drainage issues. Aside from the esthetic and structural problems caused by runoff, the cumulative effects on city storm sewer capacity and flood control make this a growing problem as we face more extreme weather due to climate change.

Our solution is only one of many possible approaches. Several online resources are available to help homeowners with rainscaping.

Here are a few:

https://www.iowaagriculture.gov/press/rainGarden.asp

https://www.polkcountyiowa.gov/conservation/education/rain-gardens/

https://www.nrcs.usda.gov/wps/portal/nrcs/ia/communities/NRCS142P2_011811/

https://iowastormwater.org/rainscaping/rainscapes/rain-gardens/