If you'd rather not use chemicals in your vegetable garden, you can control weeds, diseases, and insects by other means. The primary means of controlling weeds without chemicals is mechanical good old-fashioned weeding. Remove weeds with a hoe or rotary tiller while they're small and before they compete with vegetables for water, nutrients, and light. Never let weeds go to seed in the garden.
Some weeds can produce hundreds of thousands of seeds from one plant.
Controlling weeds also will help control insects and diseases. Many insects and diseases overwinter in weeds, as well as in crop residue. Turn old, spent vegetable plants under the soil as soon as possible after harvest to reduce overwintering sites. Other nonchemical methods of pest control include using mulches, avoiding plant stress, rotating plantings, maintaining good air circulation, timing plantings, and general sanitation. There are barriers, repellents, traps, baits, and beneficial insects.