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Waterlogging
Into every life some rain must fall – just don’t let it water-log my lawn…
To quote the stereotype it’s true that the English love to talk about the weather as much as we like tea, crumpets, and the Antiques Roadshow. However, although we know it’s guaranteed to rain, it is impossible to know how much we are going to get – just ask the Met Office.
When we get too much rain, there comes a point where the soil struggles to absorb any more water and it gets saturated to the point where it becomes waterlogged. Stepping onto a waterlogged lawn you will notice the soil feels `squelchy’ underfoot and in some cases, puddles may form on the lawn. In extreme cases, the lawn becomes flooded and submerged, whilst prolonged waterlogging can cause lawns to suffer and in extreme cases, it can die.
What Causes Waterlogging?
This really is as straightforward as it sounds. The soil becomes waterlogged when water builds up and is unable to drain away, which in turn creates various issues for the grass. A sudden downpour rarely harms the grass plants which make up your lawn, it is prolonged periods of saturated soils that cause the most damage.
Waterlogging brings a number of problems, one being the presence of the water itself which limits the crucial oxygen supply to the grassroots. It also prevents carbon dioxide from diffusing. The roots’ functionality is reduced or even stopped completely as they start to die, which in turn enables the invasion of rot and decay organisms. In addition, essential nutrients are leached out which results in hungry soil as well as severe compaction. The lawn can also thin out, creating an environment where moss will pitch-in to the new gaps and thrive in the damp conditions.
Regular aeration can prevent the lawn becoming compacted and reduce risk of waterlogging in the first place but if you have a more severe drainage issue, more extreme measures may need to be considered.
How to Deal With a Waterlogged Lawn?
- If the waterlogging was caused by a flood, then wash down hard surfaces and collect up debris to avoid drains being blocked and allow a steady flow of water to remove pollutants.
- Try not to step on the soil, as doing so will compact it and worsen the conditions.
- Remove any damaged shoots from affected grass plants.
- Once the lawn has dried out, assess the damage and what repair work may be required. In most cases saturated lawns naturally recover as conditions start to dry out but it could be that repairs are needed to reinstate a severely waterlogged lawn once the water has receded to create an environment where new grass seed can thrive. This will likely involve aeration, top dressing, seeding moss control and fertiliser application. We recommend that lawns prone to regular water-logging should be assessed to see if it is possible to fit land drainage which will relieve the problem.
Longer Term Solutions
Land or French Drains
If you have frequent/ ongoing issues with waterlogging, it may be worth investigating longer term solutions such as Land Drains or French Drains.
Both of these consists of a trench (or series of trenches), dug into the lawn and lined with a porous membrane. The trench is then filled with shingle and/or graded stone before being finished off with topsoil so that the relaid turf on the surface returns to being level with the rest of the lawn. The difference between a Land Drain and a French Drain is that the former also has a pipe (often perforated) embedded along its length to carry the excess water away more quickly and efficiently. In both of these cases, the trenches are dug at a shallow angle so the water flows along the trench by gravity to a strategically-placed Soakaway. From there it is guided to dissipate harmlessly underground. The porous membrane is designed to filter out silt from any water which is washed into the trench. Without this filtration, drains of either type can easily be clogged with silt and inundated with the very water which they exist to channel away.
Air Blast Aeration
We recommend regularly aerating the lawn due to its many benefits, but if soil underneath a waterlogged area has been badly compacted over time, a more intensive air blast aeration may be something to consider.
Unlike traditional aeration, which typically involves inserting a set of spikes or tines into the soil to a depth of 3 inches to leave thousands of bore holes behind, Air Blast Aeration uses a single spike (or pair of spikes) to drive right down to 1 metre below the surface. Once there, a shot of compressed air is blasted at high pressure, in up to 4 directions at a time. This breaks up the compacted sub-soil, helping to drain away any water which is already present and creating new channels for rainwater to drain away.
Air Blast Aeration is seen as an excellent long-term solution to waterlogging, to the point where operators are prepared to offer a 10 year guarantee on the effectiveness of their treatments. For more information, click on this link:
Hopefully, these suggestions will help your lawn to combat even the worst effects of waterlogging. Your lawn’s condition should improve as a result, but it’s equally important to stay vigilant and not let it go the other way and become too dry.