How do you fix a flooded lawn?

What should I do when my lawn is waterlogged?

Rain, rain and yet more rain – that’s exactly what many parts of the UK see regularly. Although the British population may be used to the almost constant deluge, our lawns may not. Sadly, one of the most common problems caused by excess rain is waterlogged lawns. The effects can be devastating for your garden. To drain your waterlogged lawn quickly begin pricking or slitting the surface. We recommend using a pricking or slitting tool designed to leave holes 10-15cm (4-6in) deep. It is worth remembering that the pricking and slitting methods are best carried out once the excess water has drained away.

Effects of waterlogging

Although grass can cope with wet conditions better in winter than summer, water sitting on the surface of a lawn will cause problems at all times of the year. Compaction stifles airflow and water flow to the roots of the grass. This will ultimately drown and kill the plants, leaving turf yellow and patchy.

Waterlogging also increases the rate of growth of unwanted plants like lichens and liverwort. Not only do they look unpleasant, but these plants can eventually cover wide areas of the lawn. They will stifle grass growth and kill the turf. It is therefore of utmost importance that you deal with a waterlogged lawn as soon as possible.

Two-step lawn reparation

1. Let the lawn drain

Avoid walking on it or treating it in any way until most of the water has drained away. Smaller patches can be swept towards areas of the garden that drain more easily. If draining only takes a couple of days, your turf is repairable. Grass that has been waterlogged for over a week is likely to be a lost cause and will need to be replaced.

2. Aerate roots

To start with, there are two ways to do this, with a manual hollow tine aerator or a powered aerator. They will both make small holes all over your garden. But, the powered hollow tine aerator will leave plugs of soil on the surface – be sure to remove them. Then, holes can be filled with topdressing soil or sand to improve future drainage.

Those of us unlucky enough to have faced storms recently now face the prospect of repairing a flood damaged lawn. But, putting the damage right depends on how long your lawn was waterlogged and just how much water the grass was under.

What does waterlogging do to plants?

The good news is that during winter, our gardens are far more tolerant of very wet conditions. Grass plants can survive being underwater for longer than when they are growing faster in summer. Water on a lawn will still pose problems at any time of year, because water sitting on the surface will create compaction. Waterlogged lawns means roots will be starved of air drowning the plant and killing the turf.

How soon can I start repairing my lawn?

It is important not to begin regenerating the lawn until the water has drained away. Walking on a waterlogged lawn will cause further compaction and just add to the problem.

If most of the lawn is dry but for one or two small wet areas, sweep away the water in patches from the better-draining parts of the garden. Unfortunately, if the grass has been underwater for over a week, it is likely it will need to be reseeded or replaced.

Step by step guide to repairing a flooded lawn

1. Repairing a flood damaged lawn – give the roots some air

First, to recover the lawn , aerate it and improve the drainage. For small lawns, this can be done with a manually operated hollow tine aerator. It will make small holes all over the garden, the deeper the better, up to about six inches.  You can buy these tools online for under £20 and they’re well worth the investment.

Then with larger lawns, it is easier to use a powered hollow-tine aerator if you can obtain one. The machine will leave the plugs of soil on the lawn’s surface which should be removed. Most machinery hire shops have them in store for a reasonable price. The resulting holes in the lawn should be filled with sand or topdressing soil which will improve the drainage.

2. Repairing a flood damaged lawn – give the plants a boost

Then the next step is to feed the lawn with a spring fertiliser once it begins to grow again as the temperature improves. By this time, it will be clear whether any areas of the lawn have been killed by the flooding and whether these areas will need to be reseeded or replaced.

Avoiding flood damage

As always, prevention is better than cure. Topdressing and aeration can improve your lawn’s drainage and prevent flooding in the first place. Keeping your lawn healthy and feeding it in spring and autumn will also mean it can survive longer in floods. If you have very heavy clay soil, it may be best to replace the lawn rather than recovering the lawn only for it to flood again.

Laying a new lawn on top of several inches of sand and loam topsoil could solve the problem – though in extreme cases, it may be necessary to install drainage.