How to fix a garden that stays wet after rain

Why standing water kills things

Roots need air as much as they need water, and that is the bit that surprises people, because a plant sitting in a puddle looks like it is being looked after rather than drowned. When water fills every gap in the soil there is no air left in there, the roots stop working, and the fungi that cause root rot get exactly the conditions they have been waiting for. So a plant in a wet spot goes yellow and sulks and dies looking for all the world like it needed more water.

Before you dig anything, have a look at what is actually happening after the next decent rain, because the fix depends entirely on which of these you have got.

• Water sitting in a low spot. Everything drains into one corner and stays there. That is a shape problem rather than a soil problem.
• Water sitting everywhere, evenly. The soil itself is not letting water through, which around here usually means clay.
• Water sitting where people and mowers go. A worn track across a lawn, or the strip along a path where everybody walks. That is compaction.
• Water running straight off and not soaking in at all. A hard crusted surface or a mulch that has gone water repellent, so it is not a drainage problem so much as the opposite.

Start with the cheap fixes, because they usually do it

Open the ground up

For a compacted patch, a garden fork pushed in and rocked back, every hand span or so, right across the area. You are not turning it over, you are just making holes for air and water to get down. On a lawn a hollow tine aerator does the same job and pulls little plugs out, and you leave the plugs on the surface to break down. This is the fix that costs nothing but an hour, and on a lot of blocks it is the whole answer.

Gypsum through clay

Gypsum is the standard treatment for heavy clay and it works by getting the clay particles to clump together into crumbs, so water can move between the crumbs instead of sitting on top. I will be honest with you though, it does not work on every clay, and the type it does nothing for looks exactly the same in the ground. So do a small patch, give it a few weeks and a couple of decent rains, and see whether that patch behaves differently from the rest before you buy enough for the whole yard.

Organic matter, constantly

Compost and aged manure worked into the top of heavy soil is slower than gypsum and more reliable than gypsum, because you are physically changing what the soil is made of rather than getting it to rearrange itself. It is not a one off either. Heavy ground wants organic matter going into it every year, and the improvement stacks up in a way that is genuinely noticeable after a couple of seasons.

Build up instead of digging down

Where the ground is beyond reasonable help, stop fighting it and put the growing bed above it. A raised bed on top of bad ground gives the roots somewhere with air in it, and treated pine sleepers make a bed that will outlast your interest in the project. We cut timber to length on the saw bench while you wait, so you can turn up with the measurements rather than a plan to cut it yourself in the driveway.

Put the right plant in the wet bit

One corner of nearly every yard stays damp no matter what anybody does to it, and the low fuss answer is to stop planting things that hate it. Something that tolerates wet feet in that spot will look after itself, and you get to spend the effort somewhere it changes the outcome.

The thing not to do

Do not dig sand into clay. It is the most common piece of advice going and it is the one that makes things worse, because a bit of sand through a lot of clay fills the gaps and sets harder than what you started with. If you are going to use sand it has to be a genuinely enormous quantity to work, which is why nobody ever manages it in a home garden. Gypsum and organic matter, not sand.

When it is a trench job

Sometimes the water has nowhere to go and no amount of soil work changes that, and then you are into a trench with a drain in it, running the water somewhere sensible. That is a real job with real depths and falls involved, and it is worth getting somebody who does it for a living to look at where the water should end up before anybody starts digging, because getting rid of your water into next door's yard is a conversation you do not want to be having.

None of the soil work above is hard. It is just unfamiliar, and those are different problems.

Shop related products

• Neutrog Upsurge Crumble 20kg. A soil conditioner in a crumble, for working through heavy ground.
• Naturally Good Mushroom Compost 25L. Organic matter by the bag, which is what heavy soil is short of.
• Neutrog Whoflungdung Mulch 20kg. Mulch on top, so the surface stops sealing over and shedding water.
• Seasol Seaweed Concentrate 600ml. For roots that have had a hard time sitting in water.

Did you know we also stock bagged gypsum in 10kg and 20kg, lawn aerators, garden forks, Easy Wetta wetting crystals and treated pine sleepers for raised beds. Most of that is not on the website, so give us a ring on (08) 8536 4333 to check what is on the shelf.

The soil conditioners and the mulches are in the garden centre and the online range is in garden products. Sleepers and the rest of the timber sit in building materials.

Sleepers and bagged soil are both awkward in a car, so we deliver. Strathalbyn is $5 and the wider run is $10, Tuesdays and Thursdays, with the towns listed on the local delivery page.

Read next

• How to turn compacted soil without wrecking your back
• How to keep a garden green on less water
• How to prepare your soil for a winter vegetable garden

I am a big believer in doing the cheap fix first and seeing what happens, which is partly good sense and partly that I would rather not dig a trench.

Cheers,
Candeece