Annual weeds complete their life cycle—germinating, flowering, setting seed, and dying—within a year. They often emerge in disturbed soil, hindering the establishment of desired plants. Biennial weeds, on the other hand, take two years to complete their life cycle, growing without flowering in the first year and producing a flowering stalk in the second. Both annual and biennial weeds reproduce solely by seed, such as cheatgrass (annual) and many thistles (biennial). The key to controlling them is preventing seed production.
Perennial weeds live for three or more years. Simple perennials, like dandelions, grow singly with a large taproot and reproduce only by seed. Spreading perennials, such as bindweed, start from seed but spread vegetatively once mature, reproducing both by seed and asexually, making them particularly difficult to control. Effective management involves preventing seed production and completely removing or killing the entire plant, both above and below ground.
Hand-pulling: Hand-pulling involves digging out the above- and below-ground parts, effectively controlling annual and biennial weeds. For plants with deep taproots, such as many biennials and simple perennials, complete removal is necessary
Mowing: Mowing can prevent seed production if done as weeds begin to flower, but it must be repeated regularly. While mowing effectively manages annual and biennial weeds, it only slows the spread of perennials and requires additional control methods to kill them
Mulching: Mulching with a 3-4 inch layer prevents seed germination
Chemical control: Chemical control, using organic or synthetic herbicides, can manage all weed types if applied correctly. Carefully read and follow the label, never use an herbicide in a manner inconsistent with the label. Avoid applying to annuals or biennials after flowering, as it will be ineffective
***Hand-pulling, mowing or mulching alone will not kill perennial weeds, especially spreading perennials. Multiple control methods must be used.***
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