Grubs can be a real menace in the garden. The worms are actually the larval state of scarab beetles, including Japanese, June and green beetles. Grubs feed on the roots of grass, ornamental shrubs and garden plants. In the garden, grubs will leave circular holes and depressions in root crops, such as potatoes, turnips and carrots. While you can use a series of chemicals on lawns to control grubs, this is not advisable for vegetables that you can eat. Instead, you can control grubs using a combination of cultural practices.
Plow your garden soil in late summer or early fall with a rototiller to expose grubs to the air and to predators such as birds. Do not break your ground up again in spring. Grubs are primarily a problem in areas where the ground was broken in spring.
Avoid rotating root crops into areas that previously held strawberries, corn grass or potatoes. These plants are favorites of grubs.
Keep your garden free of cover crops, such as clover and weeds. Adult beetles prefer to lay eggs in areas with groundcover or vegetation on them. This is why grubs are a problem in lawns.
Mix organic amendments, such as peat moss or compost, in your soil with a rototiller to improve drainage. Grubs prefer waterlogged, poorly-drained soils.
Avoid planting crops near plants that beetles prefer as host plants. Japanese beetles prefer roses and grapes. June beetles prefer oak trees and green beetles prefer ripening fruits, such as peaches.
Hand collect grubs from the ground as you rake and plow a garden. Throw grubs into a bucket of water and liquid dish soap to kill them.
Release beneficial insects, such as robber flies, into your garden. Robber flies will feed on grubs, thus killing them.