Click on the 'C' at the bottom of the page, and you'll find 'Clay plants' guest.

You could also improve your soil by digging in lots of organic material, home-made compost, well-rotted manure, mushroom compost plus horticultural grit.

Also remember that despite all of its disadvantages, clay soils tend to be very fertile and retain water far better than sandy ones, which is a big advantage in drought conditions.