Understanding Lawn Drainage & How To Improve It

Making sure that surface water has somewhere to go after rainfall, no matter how heavy, is crucial to maintaining a healthy lawn and garden. After all, whilst watering plants is a necessary part of keeping them healthy, at the same time excessive water will be too much for them to cope with.

Soil Type

It’s important that your garden is able to drain just the right amount, and there are obvious causes for incorrect amounts of drainage. If the soil in your garden is particularly sandy then it may not be able to retain sufficient water to feed the lawn and plants as the porous nature of sand means the water will simply drain through it. On the other hand if you have clay based soil, or soil that is compacted then the water will have nowhere to go at all, leading to too much retention of water in the soil, and by extension the plant life.

Water loss due to evaporation and Transpiration

It’s important to remember that this issue isn’t purely governed by the make-up of your soil, there are several other factors that affect the success of your garden’s health when it comes to drainage. Perhaps the second most important area is water loss in the environment, either by evaporation, or evaporation via the plants, known as transpiration. These processes remove much of the water from the soil, but during colder conditions when less evaporation takes place, then this effect will be lessened.

The types of plant in the garden

Most plants will suffer from being in closely compacted/or dense clay based soils, not just because these conditions prevent sufficient water from reaching them, but also because their delicate roots are unable to penetrate the soil and establish themselves. It also means that air cannot reach them, preventing respiration from taking place.

Plants and grasses that are better adapted to wet conditions are able to survive in part because they take in water, and air through openings on the exposed part of the plant rather than the roots. In general though, even the most well adapted plants need some space in the soil in order for air to reach the lower ends of the root network, so keeping soil well aerated is imperative.

Improving Drainage

If your garden sits on a natural slope then excess water can be encouraged to collect in a purpose built furrow or trench at the lowest point. This can be dug by hand or mechanically depending on the size of the area, and dug sufficiently large enough to keep the rest of the area free of water, whether on the surface or within the soil.

As touched on above, if dense or compacted soil is the culprit then it becomes necessary to aerate or break up the soil. This can be undertaken at the most basic level with a hoe, or you might want to rent a tiller for larger areas. As part of this process it’s a good idea to introduce a permeable material such as compost. Give yourself a head start on growing lawns and other plants by adding fertiliser into the mix as well.

Other than this consider elevating important areas such as flower beds, and placing drainage channels to their side, ideally funnelling towards the lowest point in the garden.

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