The best definition of a weed is a plant that grows where it is not wanted. Invasive weeds are those that grow in the wrong place and are very hard to get rid of. These have been categorized as nuisance, noxious, and restricted. Nuisance weeds are kept in check to prevent their spread; they may be problematic but do not threaten habitats or species. Noxious weeds are controlled and can cause problems with habitats. Finally, restricted weeds are destroyed when found. These weeds threaten other species of plants or animals with extinction.

 

Weeds are further classified as perennial or annual forms. Perennial weeds come up every year from the same roots. Examples of this type are thistles or quackgrass. Generally these weeds have swollen roots which store energy much like perennial plants; some even begin as perennial plants brought into the garden. As a result these weeds are very hard to control. Chemicals that are effective on these plants will also kill or damage ornamental plants and are uaually not reccomended, though Round-Up can be carefully painted on the leaves of the weed. Cultural methods include trying to remove the entire plant, simply removing the top every time it comes to the surface (eventually this will exhaust the weed's energy supply) and using landscape fabric in evergreen plantings or perennial beds.

 

Annual weeds sprout from seed every year; the plants do not survive the winter. Because of this, annual weeds seed themselves in greater profusion than perennial weeds. On the positive side, these weeds are much easier to take care of. A consistent program of cultivation, that is turning the top inch or so of soil over periodically, will destroy weed seedlings. If your vegetable or annual garden is heavily infested an application of Round-Up on a warm spring day before you plant will be successful on any weeds that have germinated. Never spray Round-Up near the leaves of any plants you wish to keep such as perennials, ornamental trees, evergreens, annuals, or vegetables because it is a non-selective herbicide and will kill or damage every plant it touches. Chemicals like Killex, or selective herbicides that kill everything except grasses, are not reccomended because they remain active in the soil and will damage anything planted in the area.