Make your own compost, and when it's ready after a few months, either dig it in, or use it as a mulch around your plants. Keeping a compost bin going is the best possible thing - and it costs nothing.

If you need to do something quicker, you can buy bags of 'soil improver' and then add chicken manure pellets, which are an excellent fertiliser. Dig this in, or spread it round the plants and let the worms take it into the soil.

Spritzhenry's advice is good - other options for improving the soil and thus the conditions for plant growing are, spent mushroom compost, composted horse manure from the garden centre, soil conditioning compost from the garden centre, leaf mould, anything like that you can get hold of.

Even straw, newspaper and cardboard can all be used to mulch the ground.