It is very important that you mulch your vegetable garden, to help the soil maintain moisture and to protect the soil surface from scorching weather or frosts.
There are two types of mulch that are mainly used in vegetable gardens – pea straw or sugar cane mulch. Both of these are excellent mulches, will gradually break down and, in the case of the pea straw, add nutrients to the soil.
Bark or wood chips or old newspapers are not recommended for your vegetable garden.
And remember – do not mulch over your onions! The onion bulbs do need to be able to break the top of the soil and ripen in the sun.