After the weather we’ve had recently it occurred to me that you might be interested in Rain Gardens. It would be nice if these gardens were about the magic of a rain shower , refreshing our senses and firing our imagination – but they’re not. They are basically ways to store rainwater so it has time to filter slowly back into the earth and not just rush into storm drains and back into the sea taking valuable soil and minerals with it. Here’s one by Olympic Park designer Prof. Nigel Dunnett in the London Wetland Centre.
The amount of rain in urban areas that flows into drainage systems from roofs and hard areas can be enormous, so the more rain that gardeners can temporarily collect, slow down or retain the better. These swells of water can then be used to advantage to make temporary wetland areas, thus increasing biodiversity on a garden sized plot.
Rain gardens encompass all the elements that can be put to use to collect and move water: roofs, gutters, downpipes and channels, as well as planted areas and ephemeral pools.
The least efficient surface to collect water in a garden is a flat area of concrete; a close-mown lawn would be preferable, but an area of herbaceous and shrub planting would be better still. The ideal solution is to mix in a few small trees to the lower-level planting, as this not only helps retain the downfalls, but also attracts wildlife. The diagram gives a rough idea of how it works – and yes – it’s not tricky at all. Here are a couple of books which give a thorough grounding in the basics: ‘Creating Rain Gardens’ by Cleo Woelfle-Erskine and ‘Rain Gardens’ by Nigel Dunnett and Andy Clayden – both published by Timber Press.