Although it is one of the most fertile types and many plants will thrive if it is prepared well enough.
The trouble is, when clay soil is wet it is just a sticky mass that won’t break up easily, but when it is dry after a period of hot weather it goes as hard as concrete and is impossible to dig.
In cold, wet weather, compacted clay soil produces pools and puddles and many of your plants may not tolerate having their roots waterlogged.
If you walk on clay soil when it’s wet, you compact it more. And bulbs don’t like it because they tend to rot if they are sitting in water all winter.
To assess if you have a clay soil, squeeze a handful of your soil and if it sticks together and is easy to mould, then it is clay.
The best way to improve a clay soil is to open it up by adding plenty of coarse grit, about one wheelbarrow full to every two to three square metres.
Also add plenty of organic matter, well rotted manure or compost to provide the plant nutrients vital for plant growth.
If you don’t have easy access to horse manure, then buy some mushroom compost, which will also do the trick.
But don’t use this if you want to grow acid-loving plants such as camellias, azaleas and rhododendrons, as it contains lime, which they hate.
Eco-friendly gardeners who want to avoid using peat as a soil conditioner can use composted straw instead, although there are many other peat substitutes on the market.
Different areas need different treatment. If you are creating a new lawn on clay soil, the area should only be dug to a spade’s depth as grass roots don’t go very deep.
For a big area, save some time and energy by hiring a rotavator from a local hire shop.
For borders you will need to double dig if there is a layer of compacted soil beneath the topsoil which won’t let the roots of plants penetrate unless it’s broken up.
To double dig, make a trench the width of two spades, dig organic matter into the base using a fork and breaking up the soil.
Continue to dig down the plot, turning the soil into successive double-width trenches. Use soil removed from the last trench to fill the first.
Heavy blue or yellow clay subsoils should not be dug as you don’t want to mix the infertile lower layer with better soil above. Simply pile on deep mulches to improve the soil.
On really heavy soil it’s best to mix in a good thick layer of coarse grit as well as the organic matter in the bottom of each trench, plus more of both with the soil you use to refill the trench.
By adding all this extra bulk, you will raise your borders above lawn level, which will help them drain more easily.
It is important to dig clay soil at the right time. Don’t do it when it’s waterlogged and sticky or when it’s dry as a bone.
Autumn and spring are probably the best times, but pick your days carefully, when there hasn’t been a heavy downpour and ground isn’t waterlogged.
If you dig it in the autumn, you will find that the winter frosts break it down into smaller clods, which will make it easier to manage in the spring.
Planting as much as you can also helps as the roots of plants open up the soil as they grow.
It may seem like a lot of work, but the advantage of clay soil is that it contains masses of nutrients. Roses love it and will perform well and another advantage is that clay soil does retain water.
Author: Jonny
Author of Gardening Life!