Plants for a green roof

Posted: Friday 8 June 2012
by Kate Bradbury

When I look at my green roof, I don’t know whether to laugh or cry [...] it looks very lush and green, but I wish I’d never planted those red campions.

When I look at my green roof, I don’t know whether to laugh or cry. I made it (with some help) in autumn, hoping it would fill a dead space with plants, reduce the amount of water rushing into the drains when it rains, and attract wildlife. It has done all of those things and it looks very lush and green, but I wish I’d never planted those red campions.

The red campion is one of my favourite wild flowers, not least because it grows in my garden (many ornamental plants refuse to because of the pitifully small amount of sun the garden gets). I planted it among foxgloves at the back of a tiny border, behind a lush green hebe and in front of a honeysuckle. Its pink flowers complement the green of the hebe beautifully and it covers the bare bit of trellis before the honeysuckle gets going. It’s my favourite area of the garden – it looks effortless and (dare I say) stylish, unlike the larger border, which still needs a bit of work.

It’s a reliable plant too – red campion featured in many of the gardens at the Chelsea Flower Show this year, presumably because it flowers regardless of the weather, unlike other plants that might otherwise have been used.

But it’s not a plant for green shed roofs, which I have learned to my cost. The first mistake I made was thinking the roof would get no sun. It leans against the north-facing wall, and the plants beneath it are in permanent shade. But the roof is elevated, so it gets as much sun as the south-facing border (around two to three hours a day). The second mistake I made was thinking the smaller root run of the roof would mean the plants wouldn’t grow as tall as those in the border (about 30cm). Not so: they’ve grown taller. Then the winds came and blew the plants down and I’m left with a shed that looks like it has a bad (albeit colourful) comb-over.

So what to do? I could remove the red campion, in the hope that the plants beneath it have survived. Or I could just leave it until it’s finished flowering. The bees are certainly enjoying the nectar and pollen, and the other night, while trying to decide what to do, I caught a glimpse of a large moth visiting the blooms. Aesthetics aren’t everything, I suppose.

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janfran 11/06/2012 at 11:21

I have made a green roof on top of a sloping shed just outside my backdoor. I trawled the internet for advice and placed several layers in a frame (membrane, old towels, rough gravel, soil, grit etc). I have planted it with sedums and sempervivums. I did this early in the year (March I think) and everything has already grown really well. I left plenty of space between plants and I have also tilted the shed slightly, and used a chain under the front ridge of the roof along which the water drips, and then goes down the chain at the end into a bucket. It is in shade for much of the day but this hasn't been a problem so far. I thought all the rain we had would rot the plants but so far, so good. One note of cuation, she little shed is now harde to move; well impossibloe really!