Clay Soil


Hello, I live in a house in Toronto with clayey soil. Recently some workers were burying a line and had to dig down about 3-4 feet, and they seem to have left the lower down soil on top. I have dumped my garden compost on top and some cow manure and mixed it in with the top of the soil.
so my questions are:
1) How deep should I mix compost in the fall each year?

2) Should I cultivate or hoe or otherwise try to loosen the soil in the growing season or before I plant seeds? I’ve heard mixed opinions.

3) Is moss growing on the surface due to the slow drainage of clay bad?

4) Should I add coir as well as compost/composted manure to improve drainage?


Presumably you are intending to grow plants in this area where you are trying to improve the quality of the soil.  The best way to amend clayey soil is to add organic material such as manure, leaf mold and compost, so you are definitely on the right track.

  1. The organic material should be spread on top of your existing soil and be at least 2 or 3 inches deep. It would be best to dig in or mix this into the top 6-7 inches  of your existing soil.
  2. Cultivate or hoe the soil to break it down before you start planting, as its a lot easier than trying to do this around plants.
  3. Moss growing is usually an indication that the soil is either slightly acidic, very moist, poor nutritionally, a shady area or the soil is very compacted. Adding compost etc. and cultivating the soil will help improve any drainage issues which most likely is the cause of the moss growing in your garden. If the moss lingers you may want to take it a step further and get your soil tested for acidity.
  4. Coir comes from the fibrous inner shell of the coconut. Coir is great if you want to improve the water retention of your hanging basket or container.  It is true that coir is less acidic than peat moss and could help with your moss issue. However, it retains water rather than helps with drainage.

For further information visit the Toronto Master Gardener website at and conduct a search for “clay soil” and you will be presented with a number of posts on the topic of amending clay soil. Below is a link to one of the posts.


How to Fix Clay Soil