When a burst of heavy rain regularly means small ponds forming on your lawn, you know you’ve got a problem.
Those familiar with heavy clay will have learnt tricks for treating waterlogged soil, but for those new to it – or whose garden has flooded for the first time – here are some tips for fixing drainage and reconditioning soil.
Soils are generally sandy, clay or loamy. All can become waterlogged at times but clay is most prone to this, because its particles are finer, leaving little room for air. Clay also holds onto water better – great in droughts, but not so good in floods! To test your soil, take a spoonful, add some water and see if you can roll it into a ball – if you can, it’s clay.
Why is soggy soil bad?
When water fills the air spaces between soil particles, the plant’s roots can’t breathe and neither can the worms or the soil’s microbes and bacteria that need oxygen. After a while, these die and the microbes that don’t need oxygen take over – but as part of their anaerobic lifestyle they produce smelly ‘swamp’ gases and can make the soil acidic.
Excess water can wash away precious topsoil, too.
Add the issue of rotting underground tubers – on plants such as potatoes and dahlias – and the loss of soil nutrients, and you have a growing problem.
The fix
The first rule is not to dig clay while it’s wet, as this damages the soil’s structure. Also avoid walking on it, as this causes compaction, making it harder to fix.
When the soil has started to dry out, aerate it by going over it with a garden fork, digging it in every 10–15cm and rocking the tines to create air pockets.
Next, apply gypsum – about a handful scattered over each square metre. Gypsum offers a temporary fix; it creates a chemical reaction that helps bundle the clay particles together so the soil holds more air and becomes more manageable.
Allow a few weeks for this magic to take place, then while it’s still in a good, friable mood, work on more long-term solutions.
The number one fix for any soil is home-made compost, but adding any organic matter helps create air pockets, improve drainage and replace/feed lost microbes. You can add well-rotted manure, dig in fresh garden scraps, bury your kitchen bokashi bin or, for a bare veggie patch, plant green manure.
Mix it up
Green manure can comprise any spare seed you have, or you can buy specialised mixes; these usually contain beans, mustard, a grain and a root vegetable, such as radish. Let the plants start growing then cut them back before they flower, leaving the greens as a mulch on top. The roots help stabilise the soil while the green mulch feeds the worms, adds bulk to the soil and suppresses weeds. It takes a while but it’s worth it.
Long term, you can reduce the risk of waterlogging by creating drainage trenches or building up garden beds.
In vegie patches, put down planks or paths to walk on to avoid compacting the soil, or create raised beds that lift crops well above the water table.
Happy gardening!
Do you know your soil’s composition? Has it changed the way you garden? Why not share your experience in the comments section below?
Also read: How to create a beautiful garden without spending a fortune
