Gardening: How creating a ‘rain garden’ can help tackle climate change

The Working Wetlands Garden at Washington Wetland Centre. Picture by Ian Henderson
The Working Wetlands Garden at Washington Wetland Centre. Picture by Ian Henderson
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Gardeners are being encouraged to try ‘rain gardening’ as a way of coping with the effects of climate change at a new WWT Washington Wetland Centre garden exhibit.

It’s likely that our gardens will need to withstand more periods of both drought and heavy rain in future and the centre’s new Working Wetland garden, unveiled this week, is demonstrating how to manage too much or too little rainfall.

My pond surrounded by a bog garden on the left and permeable gravel so any excess rainfall can drain away.

My pond surrounded by a bog garden on the left and permeable gravel so any excess rainfall can drain away.

The garden was originally exhibited at last year’s RHS Hampton Court Palace Flower Show, designed by Jeni Cairns, where it won a coveted gold medal and Best Show Garden.

It assumes a green roof will be impractical, so instead it channels rainfall off a central roof into a series of recycled troughs filled with gravel and marsh plants.

Anyone can do this instead of having your drainpipe pointing directly into your drains.

The troughs filter out dust, leaves, twigs and bird poo. The marsh plants take up some of the water, but after heavy rain, the troughs overspill into a pond surrounded by plants. Some of the water slowly evaporates or transpires away.

A huge diversity of planting for pollinators at  the Working Wetlands Garden. Picture by Pete Morris

A huge diversity of planting for pollinators at the Working Wetlands Garden. Picture by Pete Morris

The pond can overflow into permeable paving, flower beds and hollows, all of which allow water to soak away slowly into the ground.

WWT Washington’s centre manager Gill Pipes said: “The concept is really simple. It’s just a case of holding back rainwater and releasing it slowly. This helps to stop the garden from flooding during heavy rainfall, and keeps water reserves back for when it’s dry.

“If your garden slopes downhill, you can even use a series of troughs, channels and ponds as a slow watering system to regulate water flowing through your garden.

“The fact the pond is rain-fed with clear, clean water helps to attract wildlife. By slowing down water running off your garden you’re also helping your local environment cope with floods and drought too.”

Pelargoniums, often called geraniums, root easily at this time of year.

Pelargoniums, often called geraniums, root easily at this time of year.

The Washington garden uses 85 different plant varieties, most of them British natives, including purple loosestrife, flowering rush, greater spearwort, cornflowers, teasels, scabious, foxgloves, meadowsweet, ragged robin, and yellow flag iris.

The Working Wetland garden has been donated to WWT by HSBC as part of its Water Programme. For more information, visit www.wwt.org.uk/wetland-centres/washington/

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JOBS TO DO THIS WEEKEND

Cuttings can be taken and grown on in the greenhouse. Fuchsias and Pelargoniums (geraniums) are good candidates.

Cutting back plants in baskets followed by feeding can encourage new growth and help revive tired displays.

Plants with a carpet-like growth habit, e.g. some alpines, can become patchy, with central areas dying off. These patches can be in-filled with gritty compost, to encourage re-growth.

Some late-flowering border perennials may benefit from a quick-acting feed before they come into bloom, especially if the soil is not very fertile.

Start collecting seed from plants you want to grow next year, especially hardy annuals such as Calendula, poppy, and love-in-a-mist.

Take semi-ripe cuttings of shrubs such as Choisya, Hydrangea, and Philadelphus. Root in pots of gritty compost in a cold frame or even with a plastic bag tied over them.

Clematis can be propagated by taking internodal cuttings (i.e. taking stem sections above and below a leaf, and not cutting the stem immediately below a leaf joint).

Brown patches on conifers may show an earlier infestation by the cypress aphids. Telltale signs include black sooty mould along the stems and shed skin cases. Spraying earlier in the summer may have helped, but once the damage is done, conifers can take a long time to recover. Where hedges are affected prune out brown shoots and tie in neighbouring branches to help fill the gaps.