What to do if your garden is waterlogged
The UK has been hit with increasingly erratic weather over the last few years and none more so than the recent heavy rainfall and high winds that we have all experienced. Gardeners around the country were left wondering whether their gardens would ever recover and with climate change now a fact of life, there is every reason to expect that these volatile and extreme weather conditions will continue in the future.
Heavy rain causes flooding and many areas to suffer from waterlogging where water sits on the soil surface and either fails to drain away or does so very slowly. Certain types of ground are much more susceptible to waterlogging than others, such as dense clay soils and ground that is badly compacted which are more prone to waterlogging. They tend to stay wet after rain or flood for much longer, have a high water table and appear where water is always close to the soil surface. Areas that are situated near water are also highly susceptible to flood and waterlogging.
The occasional flash flood won't kill plants but sitting in saturated soil for a prolonged period of time can be fatal. When the ground is waterlogged the air spaces in between the soil particles fill up with water and plants literally drown. Also, their roots can't get access to oxygen and start to die and this affects the plant above ground too, as leaves and stems can't get water and nutrients.
One saving grace about the recent weather is that it occurred over the winter when plants need less oxygen, and can cope for much longer in a waterlogged garden than they would in warmer weather later in the year. Plants stuck in a waterlogged garden will start to show symptoms similar to those caused by drought. They are stressed in much the same way and display yellow leaves, wilting, rotting roots and stunted growth.
If you have suffered from flood or waterlogging recently and are wondering what to do, the most important thing is not to walk on a waterlogged garden until all the water has drained away. Walking on a waterlogged lawn will cause further compaction and make things even worse. To drain a waterlogged lawn, wait until some of the water has evaporated and the lawn is once more visible, then use boards to walk on and spike the grass at regular intervals with a garden fork, leaving deep, visible holes. This will help to relieve waterlogging in the future, as well as help water to drain away properly now. Top dressing the holes with horticultural sand will also help to improve drainage.
If your veg garden has become waterlogged, wash edible crops well before eating them in case they have been contaminated - also avoid eating salads and other crops altogether that you'd usually eat raw. Don't sow veg again until the soil is dry enough; digging over soil where you are sure water has drained away will break it up and help to expose it to the air. Also, drying it out quickly and sowing green manures on bare areas of previously waterlogged ground will also help to drain a waterlogged garden and restore lost nutrients.
Give plants in a waterlogged garden a feed in spring to help them gain much-needed nutrients, or give them a generous mulch of garden compost. Any plants suffering from severe nutrient deficiency, evident by yellow, mottled leaves, need an extra boost with a foliar feed. You should keep an eye on these plants in dry weather later on in the season too, as waterlogged plants are far more susceptible to drought stress.
If your garden repeatedly suffers from flood there are things you can do to help drain a waterlogged garden. Soil cultivation is vital, so improve the soil structure by adding plenty of bulky organic matter such as compost - one barrow load of compost to every metre square of ground. Always improve the drainage in planting holes before planting by forking holes in the sides and base of the hole, and plant trees and shrubs. These don't recover from waterlogging as easily as other perennials on raised mounds, which allow water to drain more easily away.
Consider making raised beds and growing plants in them, but don't use impermeable material for paths, patios and driveways - instead, opt for bricks, gravel and sets, that allow water to drain away. Creating somewhere for water to drain away such as ditches or a pond at the lowest point, will also help. If the problem is very extreme, installing a pipe drainage system is the best solution.