Garden design solutions: 3 tips for making a rain garden
Very sadly, we have recently witnessed extensive flooding across our local area, and with extreme weather events seemingly becoming ‘normal’ now, we need to do our bit to help.
Rain gardens are one way we can make a difference. In simple terms, a rain garden is an area of planted ground which can receive surface water rainfall from roofs or paving. They catch occasional flooding and allow the water to percolate down to natural underground aquifers.
This can not only help to relieve the pressure on our drains, but it can also help to reduce the risk of our sewers becoming overloaded and raw sewerage escaping before it has been treated. Rain gardens can also help to absorb many of the contaminants and pollutants that would otherwise enter the drainage system or our local rivers.
So, how can we create our own rain garden? Here are three tips to help us get started:
1. Choose the location for our rain garden carefully
Our rain garden should be away from buildings (the minimum distance will depend on the local topography), and ideally on gently sloping ground which is well-drained and reasonably sunny. We’ll need to be able to direct the water from a downpipe to the rain garden, either via a channel of bricks or setts, or with an underground pipe. We also need to think about where any excess water could go if the rain garden reaches capacity. In many cases this could be to an existing drainage system, but it may be necessary to prepare a new soakaway.
2. Size matters...tailoring our new rain garden to our specific requirements
This really depends upon the size of the surface we want to take the water from, but we could aim for about 20% of our roof area. Multiplying the length of our house by its width should help us establish the surface area we’ll need (tip: we can use the ‘measure’ tool on Google Earth if necessary). Depth will depend on how well our soil naturally drains, but between 150 - 450mm is usually a very good starting point.
3. Under construction...building a rain garden needn't be complicated
To build our rain garden we will need to mark out a shape and then lift any turf or existing plants. We can then dig out the excess soil and use some or all of it to create a small lip or berm around the edge of our rain garden. The next step is to choose some plants to bring our rain garden to life (planted areas tend to be considerably more absorbent than lawn), so let’s look at species which can tolerate wetter soils for the lower areas of the rain garden, with more drought-tolerant plants for the upper edges. We’ll need to keep everything watered until it becomes established, but then it should largely manage itself without too much intervention.
A single rain garden on its own isn’t going to solve our flooding issues, but imagine how much difference we could make if there was a rain garden in every garden or public space in the UK. Even really small gardens can contribute with a rain garden in a well-designed raised bed. For more information, visit www.raingardens.info or other online resources.
Image credit: https://www.raingarden.uk/