Clay quandary

Credit: Brand X Pictures/Gardening/Sandra Ivany

A few plants are adapted to growing in very heavy soils, but you will have to modify the clay for most plants to do well. If the soil is merely “clay soil,” you might be able to add enough compost to make a difference; but if you have the genuine “we should open a pottery” kind of clay, you need to take an extra step, which is where gypsum comes in handy.

Gypsum is an organic, naturally occurring product (available at garden centres and feed stores) that has been used to improve the tilth of clay soil for over a hundred years. It bonds with the clay molecules and changes the structure of the soil, opening it up so that water drains and plant roots have room to grow.

Work it into the soil as much as possible, and water it down well. The free particles will eventually penetrate several metres or more into the ground – which is where the roots of your new trees will want to be. Top-dressing (on lawns or existing beds) also works; just remember to water it in well.