Wildflowers on the roof

Pete, Nicola, Lola, 9, and Nell, 6, spent three happy months during summer of 2007 traveling around Britain. Now we’re home, but the travel bug is still there. Join us for the occasional sightseeing plus tips on how to shrink your carbon footprint. This post is from Nicola.

Green roofs may be the new trend – a wildlife haven, light on materials and a boon to the city – but it turns out that not all are equal. At the same time as the Guardian’s new King’s Cross office is being criticized for having a green carpet of sedums with low wildlife value I’m sowing a cornflower mix on to the roof of our hen shed.

When it comes to sedum versus native wildflowers then the wildflowers win because they will attract such a variety of insects including pollinators like bees and butterflies. In fact I choose wildlflowers for aesthetics as sedums are generally quite low growing so on my new 3m high shed it wouldn’t have been possible to admire any rooftop greenery. What’s more the cornflower mix was much cheaper at #7.50 for a 100g bag from Norfolk’s Emorsgate Seeds. In contrast I’d need either nine sedum plugs per metre at 1.50 each (and I’ve got three metres square to cover) or to order a ready-made sedum carpet which offered little change from #90.

Instant gratification is another advantage: it’s November but I can still go ahead and sow the cornfield mix of pheasant’s eye, corn cockles, corn chamomile, thorow-wax, cornflower, corn marigold, common forget-me-not, common poppy, corn buttercup and night-flowering catchfly. To go ahead with the sedums I’d have needed to keep the rooftop soil weed free and then planted in the spring… such a long time away.

Like a volcanic tropical island most of the green roof is out of sight – around 80 per cent of the box is hardcore and gravel, most of this rescued or pounded up from bits that I’ve found in skips over the years and then left lying around our garden. To see if it is a success I’ll have to wait, but it is definitely keeping the rain off our hens which is after all its real raison d’etre.