Where did those weeds come from?
Simple perennials reproduce by seed. Dandelion is an example of a simple perennial.
Written by Peter Russell
Imagine for a moment, that it is early summer, and you just spent hours in your garden removing weeds. Then, one week later, to your surprise, new and different weeds emerged from the soil in that same garden. You ask yourself, “Where did those weeds come from? The answer is that weeds, like other plants, go through a life cycle that includes germination, growth, reproduction, and how long that weed will live. That life cycle depends on whether the weed is an annual, biennial, or perennial. Being able to correctly identify a weed by its life cycle is critical to the management of each weed. Here is a brief introduction to those life cycles.
Annual Weeds germinate, flower, set seed, and die in one year. There are two types of annuals:
Summer annuals - generally emerge as soon as soil temperatures warm in the spring or early summer. These weeds grow, flower, produce seed, and die by first frost. Crabgrass is an example of a summer annual weed.
Common Chickweed plant
Winter annuals - germinate from seed in the late summer or early fall. Young winter annual plants live through the winter then flower, set seed, and die out the following summer. Winter annuals generally cannot survive the hot summer months. Common Chickweed is an example of a winter annual weed.
Biennial Weeds reproduce by seed and complete their life cycle in two years. Biennial weeds germinate in spring to early summer and grow vegetatively forming a leaf rosette during the first growing season. After over-wintering as a rosette, the biennial weed resumes growth, flowers, produces seed, and completes its life cycle in the second growing season. Some biennial weeds flower in the spring, others during the summer months. Queen Anne’s Lace and Bull Thistle are examples of biennial weeds.
Perennial Weeds typically live for two or more years and reproduce by seed and vegetative structures including roots, rhizomes, stolons, tubers, and bulbs. There are two types of perennial weeds:
Simple perennials- reproduce by seed. Dandelion is an example of a simple perennial.
spreading perennials- reproduce by seed and vegetative structures. Ground Ivy (stolons) and Star-of Bethlehem (bulbs) are examples of spreading perennials.
If you are interested in learning more about how to identify and control weeds by using this simple equation, “Weed ID + Weed Life Cycle = Control, please join me for the workshops to be scheduled for Saturday mornings in February (Winter Annual Weeds), April (Biennial and Summer Annual Weeds), and June (Perennial Weeds).
I hope you will join me!
Peter Russell is a UConn Certified Advanced Master Gardener and Board Chair, Bartlett Arboretum and Gardens. Sign up for Pete’s series on weed identification and control here.
Sources:
Penn State Extension: Plant Life Cycles
UMass Extension: Understanding Plant Life Cycles