A weed is any plant that grows where it is not wanted. It is best to try to control weed growth in the spring and early summer, before they have a chance to develop deep, complex root systems or go to seed and reproduce. The most effective measures of weed control include cultivation, smothering by mulching, and chemical sprays. Cultivation is particularly successful in flower and vegetable gardens where chemical sprays are potentially destructive. Frequent use may be necessary, but should only be done when the soil is dry to avoid soil structure damage. Mulching is also effective in controlling weeds in gardens and orchards, and is available in various ingredients. Mulches help conserve the soil's moisture and assist in maintaining a more even soil temperature. Chemical sprays, called herbicides [ER-bih-sides], are also available in a number of weed-killing forms. Be sure to read the labels on these products to ensure you have selected the appropriate type for your particular weed problem, and follow the correct procedures to avoid the possibility of damaging the surrounding healthy grass and shrubs. For more information on controlling weeds, consult a lawn care professional.