How to make soggy gardens flood-proof

Record wet winters and squelching lawns could cause long-term damage to our gardens. The experts at the Royal Horticultural Society share their top tips on how to flood-proof sodden gardens.
After the wettest winter on record, lawns are squelching underfoot or are maybe still submerged. Borders are sodden, too, with plants that either vanished in the deluge or look unlikely to recover. Slugs and snails, meanwhile, are thriving, revelling in the unseasonal wet and warm conditions.

What will be the long-term damage to our gardens? We won't know yet, says Jenny Bowden, horticultural adviser at the Royal Horticultural Society. 

"It's prolonged saturated soil that's the big problem. London gardens do get soggy, and they do recover, but gardens that have been under water for more than a week will probably take until May to recover fully because the water table is so high, and will stay high for weeks."

There might be plant damage that isn't immediately obvious. "You might find that a shrub sends out shoots in spring, but then suddenly dies because the root structure has been damaged. 

Roots need oxygen and when the ground floods, the oxygen isn't available. Bigger plants will fare better. Smaller plants, with less of an established root system, are more likely to suffer."

Saturated soil and strong winds can destabilise trees. If you're concerned about a tree in your garden, find a local consultant at

When you can get out into the garden — and Bowden recommends using a board or instant roll-out path (see to walk on, so you don't further compact the soil or lawn — fork over the soil in beds and borders, to get more air into it.

Aerating the lawn is essential, says Bowden, as it encourages water to soak through instead of sitting on the surface, encouraging moss. "Soil under lawns, especially on London clay, compacts easily," she adds. "For larger lawns, hire a lawn aerator. 

For small lawns, dig in a fork every three or four inches, going four to six inches deep so you make small, deep holes." In mid-March, she suggests using a combined weed, feed and moss killer, resowing where necessary with a patch pack.

If the lawn is severely damaged, you might need to re-lay it — but improve the drainage first. Bowden advises laying a two-inch bed of sharp sand, then overlaying with a six- to eight-inch layer of topsoil mixed with soil conditioner.

Dirty flood water, algae and moss can make decks or paving slippery, so jetwash or clean with a plant-friendly product. Consider slip-proofing wooden steps or paths with a layer of chicken wire.

"Rain washes nitrogen out of the soil, leaving a lot of plants, such as box, looking a sickly gold or bronze," says Bowden. "In March or April, give plants a foliar feed for a quick pick-up, and to encourage roots to grow."

There is much you can do to prevent rain stopping play in future. "Consider raised beds in areas that are particularly soggy," says Bowden. 

"Plant trees and shrubs on a slight mound, so water drains away. Improve the structure of heavy clay soil so that plant roots can access air as well as moisture, using bulky, organic matter such as stable manure, soil conditioner or council landscape waste. Plant bulbs on a base of grit so that they don't rot in wet."

Use landscape materials that allow water to soak through rather than flow away into the nearest drain: permeable paving, shingle, grass.

"Make sure you give a plant the best possible start by planting it in the right place. London lavenders are suffering this year because many have been planted in shade instead of sun, and the combination of shade and wet has made them sulk," says Bowden.

"Choose plants for your garden that are tried-and-tested 'doers', such as buddleia, choisya, viburnums, potentillas. When the only certainty about climate change is that it will bring more weather extremes, we need to face the future with robust, adaptable plants."

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