Weed control in a garden is a major challenge. The chemical industries have provided an arsenal of powerful herbicides to exterminate weeds; their effectiveness is beyond question but they are toxic substances which require special care in handling and to apply, and leave residue that may be harmful to animals and can contaminate ground water and streams. Chemical herbicides have been developed chiefly for commercial agriculture, but are also widely used in home gardens. Weeds are unwanted because they appear spontaneously and compete with garden plants for water, light and soil nutrients. Weeds are native or exotic wild plants, which most of them are, but they may also be formerly cultivated plants gone wild (feral) which have become weeds. A number of grass species fit this latter example. Both non-woody and woody plants can be designated as weeds. In nature, weeds perform important ecological functions in providing food for wildlife and insects, as well as building soil in barren sites. Weeds tend to be very hardy invasive plants which are among the first plant types to occupy open wild areas resulting from natural disasters or deforestation.
Gardeners who wish to avoid using harsh chemical herbicides have several options for weed control. One approach, is to accept weeds as a part of nature. A “natural” lawn where weeds are allowed to grow, if kept regularly trimmed, looks almost as good as one that is regularly treated with chemicals. In fact, a natural lawn is more hardy than one sustained by chemicals. The oldest practice for weed control is physical; that is, the weeds are pulled up by hand or dug out with a hoe. In a small garden, this is a feasible option and also provides a good form of exercise without going to the gym. Mulching is another benign means to control weeds in flower beds and around shrubs and trees. Weeds can be cut off at ground level before a few inches of mulch is spread to cover the surface; some gardeners chose to lay down a black plastic sheet beneath the mulch to more effectively kill the weed roots. Weeds can also be killed by using a flame-weeder or boiling water. These practices may not kill the plant roots and have to be repeated on a regular basis. Weed control can also be carried out by the application of several different natural organic herbicides. Among these are corn gluten meal, which inhibits weed seed germination; common vinegar, 5-20% acetic acid, applied to plants acts as a desiccant killing the plant by drying it out; and vegetable oils can suffocate weeds. Canola or sunflower oils, as well as citrus oil extract, neem oil and pine oil are all potent weed killers. Pouring salt or salt water on the roots of weeds is also effective. These organic substances break down in a short time and do not contaminate the soil or water in which they come in contact.
Controlling garden weeds organically may be more work, but has the advantage of managing a lawn and garden that is safe for children, pets and friendly to the environment.