These seeds have the ability to become established in a wide range of environments and to remain viable over an extended period of time. Control of annual weeds, for the most part, is dependent upon the control of the seeds. Biennial weeds reproduce by seed and live for two growing seasons. They sprout and undergo vegetative growth during the first season, then flower, set seed and die in the following season. Control of biennial weeds is centered on control of the plant in the first growing season before it has a chance to set seed.
Perennial weeds reproduce both by seed and vegetatively.
They produce new top growth from buds located on the root stock. The root stock can be bulbs, tubers, rhizomes, stolons, crowns or taproots. Control of perennial weeds is dependent upon the control of the root stock buds. Appendix B , the Recommended Reading section of this FAQ, also lists a number of references. Knowing the characteristics and life-cycles of those plants counted as weeds is the starting point in their control.