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Wednesday, 23 May 2012 00:00

Rain Gardens

Come rain, come shine

We live in interesting weather, to misquote the proverb, from drought to flood and back again within weeks. 

In March we rushed out with our shorts on only to rush back in again in search of the waterproofs with April’s soggy arrival.  Many areas were flooded as rainwater ran off hard ground into rivers.  
Such weather extremes are predicted to become more common as our climate changes.   As the 2012 hosepipe ban showed, at the same time as demand for water is growing its supply cannot always be guaranteed.  It’s clear that we need to think differently about how we use and manage water both in the house and the garden.  


Planting for drought has become fashionable and will certainly reduce the amount of water needed but many gardens don’t have the right site conditions and we don’t all want lavender and rock roses.  Another option is to consider a ‘rain garden’.  Nigel Dunnett’s garden at the Chelsea Flower Show last year showed that such gardens can look amazing as well as being functional.  The idea is that the garden captures, channels, diverts and soaks up water rather than letting the surplus run off into the drainage system. Typically it could include a number of components, such as:


•    storm-water planters (above-ground plating containers that intercept water from the roof)
•    green roofs (layers of living vegetation installed on the roof that reduce water run-off)
•    rain barrels and water butts for above-ground water storage
•    rain harvesting reservoirs for below ground water-storage
•    ponds/pools
•    gullies and rills
•    porous groundcover, such as gravel, which helps absorption of rainwater
•    planted sunken infiltration areas (where the water can seep away and be taken up by plants).  

In periods of low rainfall some of these components will be dry and the planted areas will look no different from any other area of the garden but in wet periods the whole system comes to life with running water.  You don’t have to involve the whole garden to make a difference and not all elements have to be included; budget, site, soil conditions, runoff levels and how you want to use the garden all need to be considered.  But even one or two elements can help and combining two or more multiplies the benefits.     You could simply disconnect your downpipes and channel the water into storm-water planters that overflow gradually into gullies, or install a green roof on the shed.  


Planting is key in any garden but the more diverse the plants in a rain garden, the better it will work.  A well-designed rain garden will not be submerged for long periods and even in long drought periods there will be some moisture still available deeper down so there is a wide choice of perennials, grasses, shrubs and trees that would cope with such conditions.  


Unlike some eco friendly schemes, creating a rain garden need not be that complicated; the hard landscaping involved can be a lot less and expensive water features are not needed to enjoy the movement of water through the garden.  Best of all, with a rain garden you can feel good about doing your bit while the garden does the work for you.