Are you lucky/unlucky enough to have a garden or allotment with heavy clay in the soil? Or just mostly clay like my allotment?! Well, you’re in a lucky/unlucky situation. Heavy clay is, yeah let’s be honest, very difficult to work with sometimes. It gets stuck to your boots if it’s damp or wet. And heaven forbid you get a really dry spell, because it will bak e hard in the sun and crack, looking like some kind of dried up river in drought-struck Africa. Underneath, it will be tightly compacted, meaning less water and oxgen can move, even though the moisture is held in there.
However, heavy clay can also be a blessing in disguise, because even though it can be really hard to work with sometimes, it is also very fertile and certain veg actually thrive on this harder type of soil. We got our first allotment about ten yrs ago and most of it was very heavy clay that had been worked in parts and had had hens running around some of it. So we knew there were easier sections and that the fertility was high everywhere. But boy was it hard to dig and improve the workability!
Keys to Improving Heavy Clay Soil
- Add organic matter to your soil if you can – make or bring in your own compost and add this in layers (or dig it in if you’re feeling brave!). This will greatly improve workability
- Add sand if you can get hold of some free or cheap – this will break up the particles of clay and make the soil lighter, but you need to dig it in again, not an easy task
- Choose veg that thrive on harder soils (see below)
- Employ various no dig methods to save yourself the back pain – raised beds, Hugelkultur (mound gardening), doing a surface cultivation of the top few inches and then sprinkling an inch or two of compost on top
- Create permanent beds and paths so you never have to walk on the soil – raised beds or mounds work well here. You can add layers of cardboard, veg scraps, and compost, twigs, grass clippings, worn sawdust etc. to make highly fertile and biologically active growing beds for your veg
- Add a mulch – this can be a layer of compost, straw, grass clippings, or old leaves. They act as a bit of a shock absorber when it’s raining or hailing and they will break down and improve your soil over time, as well as hold a layer of moisture at the top when it gets dry, potentially avoiding the baked hard cracking we all hate!
- Use a broadfork to get oxygen into the lower levels of your soil
Which Vegetables Work Best on Heavy Clay Soil?
Certainly when you first get your hands on some clay soil, you would probably want to stick to vegetables that thrive on it, until you have built up the workability over a few years. These are the veg I have had most success with in my heavy clay (may contain affiliate links):
- all kinds of lettuces. The best were Romaine/Cos lettuces called Ballon and Red Salad Bowl
- spring onions (sown in modules and then transplanted) I grow Kyoto and White Lisbon
- pumpkins and squashes of every kind (please see specific tips for planting pumpkins in this post) I am currently growing Olga hulless pumpkins
- chard – thrived like crazy, a little too crazy haha
- beetroot – the white and red (purple) varieities did well, the white did the best
- brassica crops – kale and sprouting broccoli did very well. I’ve got cauliflowers for the first time this year and they seem to be doing fine
- onions – I started getting success with onions (bulbing onions from sets) a couple of years ago, they seem to like the firm soil, but they really thrived more when I added a really thick layer of grass clippings
This year, we have taken on a new piece of land and will be creating permanent beds and walkways in between so we never have to walk on the soil. We know there is a good layer of clay underneath, although the top several inches look like good tilthy topsoil, so hopefully I will not have as many problems as I did when we first took on our allotment.
Let me know if you have heavy clay and what do you do about it? What have you found that works for you?