Incessant winter rain reliably turns the bottom of my garden into a cold, claggy soup every year, from autumn pretty much to the middle of spring. This year a whole weekend of non-stop torrential rain – and I do mean torrential – saw water bubbling out from the bottom of my lawn by the Sunday. My neighbours tell me that our gardens stand on land once used to grow watercress. This doesn’t surprise me!
So what’s a gardener to do when faced with such extremes of weather that, in light of climate change, look set to become only more common and pronounced as the years roll by? Here are a few ideas to alleviate problems with sustained rain and sodden soil.
Improve Your Soil Structure
The success of any healthy garden relies on its soil. Add lots of organic matter whenever you have the chance. Well-rotted manure from a trusted source (so you can be certain it’s free from herbicide residues), garden compost or leafmould are all excellent at gradually improving both your soil’s structure and nutrient content.
Organic matter works to improve all soil types. It opens out close-bound clay soils, so water can pass through with greater ease, while helping sandy soils to retain moisture in dry summer conditions without adversely affecting its ability to drain in wet weather. Simply put, adding organic matter can only ever improve your soil’s structure and its ability to manage moisture.
Raise the Soil Level to Prevent Waterlogging
Raising planting areas – by piling up soil into a ridge and furrow arrangement or by creating raised beds with sides – lifts the root zone up above the general ground level and, hopefully, any saturated conditions. Raised areas are also the first to drain through once the weather does dry out, and as a result they warm up slightly earlier in spring.
Building a raised bed couldn’t be simpler and you can position beds on existing areas of lawn or even weedy areas, so long as the ground is first covered with a weed-quashing layer of cardboard. Use cut-to-size wood and fill beds with compost, soil or a mixture of the two to get started.
Manage the Moisture Using Berms
When rainwater floods into the same area time and again, a little light geoengineering may be the solution. Use berms – mounds of soil – to hold back the water or divert it elsewhere. Think of those rings of raised soil you create to hold in moisture around thirsty crops such as tomato plants at watering time. Then just scale up!
This method is particularly useful where specific areas or beds keep on getting flooded out. The downside, of course, is that all that water has to go somewhere! Carefully consider where all that water is directed to – you don’t just want to pass on the problem elsewhere. One option might be to create a bog garden planted with moisture-loving plants that will thrive in these boggy conditions. You could even develop a full-on rain garden.
How to Install French Drains
In extreme situations where the soil is almost constantly waterlogged the only answer might be to install drains that lead to some sort of soakaway.
French drains are among the simplest drains, suitable for most gardens with a gentle slope that will enable water to trickle away via gravity. Trenches are dug to follow a gradient of between 1 in 50 and 1 in 100. The trenches are then lined with a permeable membrane, such as weed fabric, which keeps the trench from silting up.
Into the lined trench go stones or rubble. Optional is a central perforated pipe, topped off with more stones so that the pipe is completely surrounded. The trench can be filled to the brim or filled most of the way to the surface before closing up with a final wrap of membrane and topping off with backfilled topsoil.
French drains must lead to an area where all that water can safely disperse (and not just into your neighbour’s garden!). The usual method is to create a soakaway by digging out a substantial box-shaped hole that’s then lined with membrane and filled with more stones or rubble. The water will fill and collect in this reservoir before gradually seeping out into the surrounding soil over a matter of hours or days.
With a little planning the rain needn’t get you down, and there’s certainly no reason for roots to sit in saturated soil for long periods. Think strategically and work with the lie of the land.