Tips to improve and break up clay soil to improve the structure and drainage

Frequently asked Questions about improving and breaking up clay soil answered on this page. 
  • What is clay soil?       

  • What are the problems associated with having clay soil in a garden? 

  • What's good about clay soils?        

  • How can I improve and break up clay soil? 

  • When is the best time of the year to dig clay soil ?

  • Recommended tools and materials further down this page.

  • The best way to improve and break up clay soil long term.

  • How soon can I plant in the improved clay soil.

If your soil looks like this It's clay
If your soil looks like this It's clay read on

Also read the Old timers tips for first time gardeners

How to dig and improve clay soil

How to improve clay soil for growing plants in my garden. 
If the clay is not causing water logging but you want to improve the structure and break up hard soil to make digging easier, these tips may help.
Clay soil can be a good thing lots of plants grow well in it.  
Clay soils are hard to dig but retain moisture better than sandy soil, clay is also rich in the nutrients plants need to grow, holding calcium, potassium, and magnesium. Improving the soil to make it easier to dig is a better and cheapest option than replacing it.
What is clay soil?
Clay soil is composed of mostly clay particles. Soil that consists of over 50% clay particles is referred to as heavy clay.  
Carry out this simple test to find out if you have clay soil: if the soil sticks to your wellies, garden spade and fork like glue and forms big hard lumps of soil that are difficult to break up and the garden surface cracks up in dry weather, it's clay.

What is bad about clay soil in my garden.
Clay soil can be a nuisance, even if it's not waterlogged. Hard clay soil is hard to dig and although many trees and shrubs grow well in clay,  the roots of the some annuals, perennials, and vegetables, especially root crops like carrots and turnips can't grow their way through heavy clay.
Clay soil is slow draining, slow to warm up in spring and compacts easily into large hard lumps of soil making it difficult for plant roots to grow. In dry weather the surface cracks up.
What's good about clay soils?
Clay soils retain moisture better than sandy soil, handy during long dry spells. It's also rich in the nutrients plants need to grow, holding calcium, potassium, and magnesium. See the note below to understand a little more about calcium, potassium, and magnesium in garden soil.
How can I improve and break up clay soil?
It's possible, with some hard work, to make clay soil more workable and suitable for planting and growing most plants and at the same time keeping the good things about clay such as nutrients essential for plant growth. Clay also has moisture retention properties.
Improving Clay Soil.

Improving your clay soil will take a lot of digging but will improve the structure of your soil and make it easier to work with. Their are two main stages: the hard work to change and improve the clay soil, followed up with the easier but just as important once a year maintenance, needed to continue improving your soil. Two simple ways  to improve  clay soil and maintain the improvement 

When is the best time of the year to dig clay soil ?
The best time of year to improve clay soil is late Spring or early Summer, right after the frosts have finished and the clay has warmed up. 
This is the best way in the long term to improve and break up clay soil.
There are no short cuts. Digging out and improving a small area or a planting hole doesn't work. The plant will be ok for a while but as it starts sending out roots that hit the hard clay, they will start circling around in the planting hole, just like in a flowerpot and will become pot bound.

The other problem with just improving a small area is the surface water draining from the clay into the area you have improved and subsequently water logging the area.

So it's best to improve an entire planting area, decide how much of the garden you want to improve and dig out any plants you want to keep. 

1 You will need to cover the entire area with about 8" of organic matter. This could be anything that hasn't been treated with chemicals, compost from your compost heap, rotted manure or lawn cuttings.

2 Now the hard bit, this can be done over several days. Dig the organic matter into the top 10" of the clay soil, trying not to compact the dug soil. Digging in with a spade is the best way but using a rotivator works ok too. Be careful if you are going to use a rotivator, it's likely to bounce off the compacted clay until you have got the hang of it. 

The garden bed will be a couple of inches higher when you have finished improving the clay soil and will settle down over a season.

3 Add more organic matter to the top of the garden bed each year, as the clay soil improves, this can be left on the surface for the worms to take it down into the clay for you.
How soon can I plant in the improved soil.
As soon as you have recovered from digging it all in. And remember - try not to compact the freshly dug soil. Use a roll out track if you are wheel-barrowing over it

Essential Minerals for healthy soil  Magnesium, Potassium and Calcium.

Types of Soil and plants and wild meadow flowers that will grow and thrive in them I have listed a few species of wild flowers that will thrive in clay here, soil wildflowers grow in and other plants here
 plants to grow in clay

There is an alternative to digging clay soil to make it workable, check out my article here  

The best tools to use digging clay.

Cheap spades and forks are not much use when digging clay soil, the handles bend and break and the fork prongs bend, I have broken more than i care to remember.
 For just a few pounds more I recommend the spades and forks I have listed here, most good gardening equipment shops stock them or you can buy now from Amazon.

Don't try digging frozen, frosted or baked clay. It's impossible even with these tools.

Grit sand for breaking up and improving heavy clay soil.

It's extra work but worth spreading a one or two inch layer of grit sand across the clay soil before spreading the organic matter and digging the whole lot in at the same time. This will help break up even heavy clay soil. You will need to work at it over the years by repeating the process though. Baked clay is almost impossible to break up, rotivate or dig, it's easier to spread the organic matter and grit and wait until the worms have done some of the work for you.
This is the Sharp Sand I use its composed of grains of rock,  with a high percentage of larger grain sizes making it ideal for improving clay soil. 
Bulk bags weigh a minimum of 800kg, cost under £70 inc delivery.
Do not use ordinary builders sand it will clog up the soil.