Horticulture Magazine

Drainage Solutions For A Waterlogged Garden

a waterlogged garden lawn

Draining away excess H2O from a waterlogged garden is entirely achievable with a little bit of forward planning and a lot of elbow grease.

There’s nothing worse than a squelchy garden which retains water. Not only is a waterlogged backyard uncomfortable underfoot and unpleasant on the eye, but it can damage the soil quality, encourage the accumulation of moss and inhibit the growth of other plants. As such, it’s an issue that can’t be allowed to fester.

There are many reasons why a garden might become waterlogged. It could be compacted soil is preventing adequate drainage, or clay soil precluding it altogether. Perhaps the problem is caused by an uneven or sloping lawn which diverts water into a place where it can gather, or a result of your garden lying lower than the land around it. Maybe it’s due to impermeable surfaces or drainage pipes from outhouses depositing water into the garden, or structural features like swimming pools or home extensions interfering with the water table.

Whatever the problem, it will only deteriorate without proper care and attention. That’s why it’s important to first ascertain that the problem is not a temporary one and cannot be avoided via preventative measures – then implement an appropriate plan of action to remedy the situation. This helpful guide will outline how you can do so safely, affordably and effectively – although the process is likely to require a significant investment of time and effort. As long as you’re prepared to put in the hard labour, there’s no reason why you can’t turn a soggy backyard space into a blooming garden of which you can be proud.

How to tell if your garden is waterlogged

waterlogging on a lawn after heavy rainfall
A soggy lawn is a sorry sight indeed

In many situations, it will be immediately obvious whether your garden is waterlogged or not. Persistent puddling which doesn’t drain away, a squelchy sensation when walking on top of it and a surge of water-loving plants like moss, reeds and other long grasses are all tell-tale signs that there’s a problem. Of course, standing water could just be the inevitable consequence of prolonged heavy rainfall, but if you suspect the issue might run deeper, it’s important to avoid stepping on the affected area as much as possible. This is because foot traffic will only compact the soil and compound the issue further.

The best way to check whether or not your garden is waterlogged is to dig a hole around two feet deep and at least one foot in diameter, then fill it halfway with water. If the liquid is still there (or has increased in volume) four hours later – without the help of any precipitation – you’re undoubtedly dealing with a waterlogged lawn and steps must be taken to address the problem. If, on the other hand, the water does drain away, but slower than expected, it’s possible that certain preventative measures will avoid a reoccurrence of the issue in future.

Preventative drainage solutions

use of a scarifier on a lawn
Prevention is invariably preferable to the cure

If you’re on the ball, there’s a good chance you can nip the problem in the bud by taking these preventative measures to improve the soil quality and avoid a descent into full-scale waterlogging. However, it should be noted that these solutions will not work in scenarios where the topographical layout of the garden or a large clay concentration of the soil is the root cause of the problem, but they may be worth a try in other circumstances.

1. Plant your way out of trouble

Perhaps the most straightforward solution to waterlogging issues is to select plants which thrive upon the particular type of soil found in your back yard and assist with its drainage. For example, gardens with a heavy clay content will benefit from species like fuchsia and geraniums, while some hydrangeas are excellent at regulating soil moisture.

2. Spike the lawn to aerate the soil

A garden that takes its time to drain after heavy rain could simply suffer from compacted soil. Your best bet here is to aerate the area, either by using a bespoke mechanical tool (like the scarifier pictured above) or manually with a garden fork or other hand spiking implement. For best results, make the holes around half a foot deep and fill them with a permeable substance like horticultural sand.

3. Collect rainwater

Your home should already have a dedicated guttering system in place, which directs rainwater into the sewers. However, any sheds, summer houses or other outbuildings you might have may not. Take the time to install guttering on them, then collect the rainfall they channel into water butts, which can be used to irrigate your plants in the dryer months.

4. Kill moss

Moss is not only a giveaway sign of a waterlogged lawn, but also a contributing factor to death and destruction in your garden. As soon as you notice moss beginning to infiltrate your lawn or other areas of your back yard, ensure it doesn’t stand a chance of corrupting the whole space by using a commercial moss killer.

5. Fertilise and feed

After a particularly wet winter, a lawn may need an extra helping hand in order to re-establish itself. That’s when fertiliser can come into its own, promoting growth of more complex and robust root systems that are better equipped to withstand waterlogging pressures. Organic matter and lawn feed can help to achieve similar ends.

6. Make a feature of it

While this course of action isn’t exactly preventative, it can be a rewarding choice in its own right. If the waterlogged area won’t respond to other measures and you don’t fancy implementing a full-scale drainage system, you can always turn your back yard into a bog garden. Careful selection of the right plants can achieve an almost exotic aesthetic and encourage biodiversity, essentially transforming the problem into the solution.

Comprehensive drainage solutions

These solutions (like this French drainage) tackle the issue head-on

If none of the above preventative measures have the positive effect you’re aiming for, it’s time to roll up your sleeves and address the problem with a more comprehensive drainage solution. Depending on the cause of the waterlogging and the layout of your garden, one of these suggestions should help:

7. Dig a ditch

The most logical and straightforward solution to standing water is to find a place where it can rest in peace. Digging a ditch is a basic but often effective method of draining waterlogged gardens that sit on a slope. Simply excavate the section of land at the bottom of the slope to a depth of at least three metres and let gravity work its magic. For best results, ensure ditch has sloping side to ease the flow of the H2O.

8. Install a French drain

Despite the name, this drainage solution is actually named after a green-fingered American by the name of Henry French, who used it to alleviate the same issue back in the 19th century. It involves digging a horizontal trench from the highest point of your garden to the lowest, with a minimum depth of 18 inches. The trench should end at a ditch or soakaway where the water can drain in its own time.

When excavating the initial trench, retain around a third of the best soil to fill it back in later. Before you do that, however, you should lay down some landscaping fabric to ensure separation of the different elements of the drain. Then, shovel around a foot of coarse gravel into the opening, before folding the fabric back over the gravel. Finish by topping the trench with the retained topsoil, overfilling it slightly to account for the settling of the earth.

This type of drain is best suited for gardens where a high clay content is the main issue at hand. It will certainly require some planning and a lot of hard work, since you’ll need to excavate and remove as much clay as the drain spans, then fill it back in with gravel. Nonetheless, it should pay off by providing a long-lasting solution to the problem.

9. Go herringbone

This type of drainage system is a variation on the French drain outlined above and is most appropriate for sloping gardens that are uneven in shape and that exhibit signs of waterlogging throughout. Begin by digging the same trench used in the French drain above, but maximise its capabilities by including several secondary ditches which split off from the main drain.

These should be placed at 10 feet intervals for clay soil or 25 feet intervals for loamy soil and connect with the main drain at a 45° angle. They should be dug to the same depth as the main drain and follow the same process of lining, filling with gravelling and finishing with topsoil. Make sure the main trench is connected to your ditch or soakaway and voila! Your herringbone is complete.

10. Perforated piping

This is a step further than any of the previous methods and will require the purchase and installation of perforated drainpipes inside your trench. Again, you’ll need to dig a horizontal trench from the highest to the lowest part of the garden and repeat the steps of involving landscaping fabric and gravel. At this stage, you should lay the piping down and surround it with gravel, before finishing with the topsoil as before.

It should be noted that this particular method of drainage has proven to be controversial among gardeners, with even the placement of holes in the pipes a matter of some debate. While it has shown impressive results for some people, it may seem like more trouble than it’s worth, especially given the additional financial outlay for the piping and the effort required to install it. In most scenarios, a simple French drain or herringbone drain will suffice, but perforated piping could provide an alternative option for those who still experience problems.

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