My green roof had a tougher winter this year – lack of snow cover meant the relatively thin soil layer heated up and cooled down a lot. Most of the plants did very well anyway, but a couple of sedum species had more winter kill. No dandelion taproots have yet emerged through my kitchen ceiling (this is my secret fear about the roof). I still enjoy looking out at it every time I go by the window at the top of the stairs and seeing the yarrow and little bluestem grass peek over the parapet from the ground.
In the wider green roof world – here’s a snazzy little tool from American Rivers using Google maps to pick a roof – your own, or the local Target store, or any downtown building and (virtually) turning it green to see how it can help improve river quality and save money. I tested it out with the roof of City Hall (which needs repair anyway) and the approximately 10,000 sf roof, if green, would save about 116,000 gallons of stormwater from reaching the river and save about $9000 in heating and cooling costs.
Although I love my little green rooflet, I’m not ready to advocate for projects like greening City Hall. Green roofs take structural reinforcement (they’re heavy with soil and all that water) and regular maintenance (see the dandelion remark, above). I’d like to know the scale at which green roofs make the most sense in terms of stormwater/savings vs. installation and maintenance. Or, what proportion of roofs in an area need to be green have a significant impact on the heat island effect and stormwater management? Would large flat roof surfaces be better green or with solar panels? Bottom line: I’m eager to keep learning about how we reduce energy costs, improve water quality and use all that rooftop real estate to help…
The thrilling conclusion to last summer was installing the green roof on our house. See here and here for previous posts. As the snow fell last winter, we wondered what would happen this Spring. Here is what grew:
I blogged about the construction of our green roof leading up to the great mud-slinging event, but now the green roof is actually green and growing.
Through some contacts at the Minnesota Green Roofs Council (you can go see their “portable” green roof at the State Fair – it’s on a small trailer), I’d heard that Dragonfly Gardens in Amery, Wisonsin was a great source for green roof plants and advice – it was. They stocked a huge variety of sedum (stonecrop) and in addition to 8 flats of assorted sedum from Dragonfly, I supplemented with some red bee balm (monarda) from my garden and some bright yellow yarrow (achillea) from Knecht’s Nursery. Justin rigged up an irrigation system. Watering the roof seems a bit odd, but we’re happy to report that the design of roof and scuppers works perfectly, the roof drains appropriately and the plants are getting established.