Stages of a Weed Plant

Type of Weed

• All weeds go through four life stages; however, different types of weeds go through the stages at different times. Annual weeds complete all four stages in one year or less. Winter annuals germinate in late summer or fall while summer annuals begin germination in late spring. Biennial weeds require two years to complete the life cycle, and perennial weeds require many years to grow.

Seedling Stage

• The seedling stage begins when the plant germinates and produces two sets of leaves: the seed leaves, or cotyledons, and the first true leaves. Environmental conditions trigger annual plant seeds to germinate. Weeds in the seedling stage are small, vulnerable and easily controlled, according to Purdue University. Young leaves easily absorb herbicides during this stage. Weeds in the seedling stage require less herbicide for control.

Vegetative Stage

• Weed plants in the vegetative stage experience rapid growth of roots, stems and foliage. The plant is rapidly taking up water and nutrients, moving them throughout the plant, which makes weeds in the vegetative stage vulnerable to many herbicides. Washington State University recommends the elimination of weeds during the vegetative stage or earlier. The herbicide quickly moves through plants in the vegetative stage.

Reproductive Stage

• Flowers appear during the reproductive stage. Depending on the type of weed plant, the process of pollination happens through the aid of insects, animals or the wind. Fruit-set occurs with seeds developing during this stage. Growth slows down, and the plant takes up fewer waters and nutrients during the reproductive stage. Manual removal of weeds should occur before the plants produce seeds. Some plants, such as cocklebur, produce seeds that are viable even when immature. The movement of herbicides within the plant is reduced during this stage, according to Purdue University.

Mature Stage

• Plants in the mature stage exhibit little growth. The movement of herbicides within the weed plant slows, with plants beginning to store sugars in their roots. Translocated herbicides become effective against perennials when they reach the mature stage.