The most common description of a weed is a plant growing where you don't want it. Weeds in the vegetable garden cause problems but weeds on the hillside provide erosion control. Weed killers are chemical herbicides that can also kill or damage vegetable plants and pose a health risk. There are a number of natural methods to control the weed problem around vegetables.
Weed seeds are very prolific and often out-produce the surrounding crops, making weed control an economic necessity. Some weeds create up to 250,000 seeds from a single plant(Ref.1"characteristics of weeds"). Thistle, milkweed and dandelion have long feather-like structures that are carried by the wind. Weed seeds stick to bird and animal feet and also pass through their digestive tracts to germinate in new areas.
Weeds compete with vegetable plants for available soil nutrients, water and sunlight. They sometimes serve as hosts for problem insects and disease organisms. Non-native plant species are considered weeds. They invade local areas and destroy naturally balanced eco-systems. Weed control in the vegetable garden can be accomplished with chemical or organic methods.
Chemical Weed Killers
Roundup is a well-known chemical herbicide made by Monsanto. Home gardeners may not be aware that it is highly toxic to reproductive health. A 2009 study at the University of Caen revealed that the "inactive ingredients" in Roundup cause significant cell damage. Farm workers exposed to chemical weed killers such as Roundup report eye irritation, headache, nausea, skin rash and other flu-like symptoms.
The Capitol District Community Garden recommends methods for organic control of weeds, saying "prevention is the best medicine." Barrier techniques include mulching with black plastic, organic materials or newspaper. Weeds may germinate under the mulch layer but cannot grow without sunlight. Cover crops also prevent weeds from gaining a hold in the vegetable garden.
Weed control for large vegetable gardens is accomplished by planting cover crops between rows. Cover crops crowd out weed growth, reduce erosion and provide nutrients for soil. Commercial vegetable growers also use cover crops as a cash crop. The University of California Davis Sustainable Agriculture Research and Education Program has identified 32 species of plants usable as cover crops. Small home vegetable gardens use clover, pea or mustard as cover crops.