Ecoroof in the Garden


Garden shed ecoroof

Last summer, my husband wanted to build a “garden shed” to replace the tiny dry-rotted structure we had in the driveway. I was thrilled about having a place to store garden tools and bikes, but struggled with the idea of having more impervious surface on our property. TJ agreed and decided to build an ecoroof on top of the shed to collect the storm water runoff.

The ecoroof captures rainfall and the overflow is directed down the sloped roof to a gutter, which flows into a 500-gallon water tank. There is a hose connected at the bottom of the tank so we can water the garden or use in case of emergency. The average annual rainfall in Portland, Oregon is about 40 inches. That is a lot of water that could be used on plants instead of going into the city’s storm drains.

TJ consulted the City of Portland’s Ecoroof Program web site for more information on design details. He had to construct the shed to withstand the weight of the soil and plants on the roof. TJ laid down a pervious membrane, hung the gutters and directed the flow into the water tank. Along three places on the roof, we placed some flat rocks above the gutter to slow down the rainfall and minimize erosion during heavy rains.

Following construction in October 2013, I climbed onto the roof with my shovel and a cup of coffee. It was time to plant!  Although I had never designed an ecoroof, I knew I wanted a mix of grasses, sedums, and spring bulbs. Below is the plant list I came up with:

Sedum Silver Moon, Red Ice SedumSisyrinchium Quaint and Queer, Armeria juniperifolia, October plant Sedum siebodii, Sedum “button”, Cape blanco – Sedum spathulifolium, black mondo grass, Echeveria secunda, Hens & chicks Sempervivum rojin, Double alpine geranium Erodium reichardii “Flore pleno”), Sedum reflexum “blue spruce,” blue oat grass, Mexican feather grass, Iris bulbs

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Michele laying out the plants on the ecoroof

Another feature on the roof is a metal bowl filled with stones and water which serves as a “bug bath” for bees and other insects. Last year, the bug bath was in the garden and was visited by tons of bees. I also put a small piece of driftwood on the roof for insects to use as habitat.

This summer, I plan to track all the critters I observe using the ecoroof to evaluate its habitat value. While our house sits on a busy city street, I see my urban lot as an important corridor for bees, insects and wildlife. The ecoroof serves as another spot in the yard for creatures to use.

TJ sold me on the idea of a garden shed and he built it using old cedar and vintage windows he salvaged from one of his construction projects. It was well on its way to being a beautiful, eco-friendly structure until he left the lawnmower in the yard, hung up our bikes and shoved my garden tools onto a small shelf so high I can barely reach them and moved in his tools and two motorcycles. As evidence in the photo below, our “eco-friendly”garden shed is really a motorcycle repair shop.  Sometimes in marriage, you just have to compromise, but I still have my planted roof and I love it.