Understanding Weeds

Weeds occupy open spaces. Designing the flower bed to utilize all the of bed space will increase competition and reduce the sunlight reaching the soil surface which will decrease the weed population. Proper soil conditioning and amendments, in concert with quality plant selection and maintenance will minimize seedling weed emergence later in the season.

Weeds compete with ornamental plants for water, light, and nutrients, reducing aesthetic quality and plant growth. To minimize these problems, a weed management program should be developed and implemented prior to planting. A successful weed management program involves four steps.

• Understanding weeds (identification and life cycle).
• Understanding the available weed management options.
• Site preparation - eliminate perennial broadleaf weeds and sedges before planting.
• Implementing a combination of effective methods to prevent and control weeds.

The first step in developing a successful weed management program is identifying your weeds and their associated life cycle. Knowing the correct name helps to understand the herbicide labels and control recommendations. Several pictorial guides are available for identifying weeds (refer to suggested references).

Most weeds found in color beds have one of three life cycles: summer annuals, winter annuals, and perennials. The weed's life cycle provides information on timing of germination and method of reproduction.

Summer annual weeds germinate in the spring (beginning with dogwood bloom) and continue throughout the summer months. They flower and produce seed prior to the first frost.

Common summer annual weeds include grasses such as barnyardgrass, crabgrass, and goosegrass; and broadleaves such as annual lespedeza, carpetweed, common purslane, morningglories, pigweed and prostrate spurge.

Winter annual weeds germinate in late summer and early fall, overwinter as small dormant but green plants, and flower and produce seed in late winter and early spring. Winter annual weeds die with the onset of warm weather usually in late spring to early summer.

Common winter annual weeds include annual bluegrass, annual sowthistle, common chickweed, hairy bittercress, henbit, horseweed and short buttercup.

Perennials weeds are classified according to their method of reproduction as creeping or simple. Creeping perennials reproduce by above ground stems (stolons) or below ground stems (rhizomes).

Of course, most perennial weeds can also reproduce by seed. Examples include nutsedge, bermudagrass, red sorrel, bindweed, groundivy, and quackgrass.

Simple perennials spread by seed, they have no natural means of spreading vegetatively (stolons or rhizomes). Their roots are usually fleshy and can grow very large. Examples include common dandelion, curly dock, buckhorn and broadleaf plantain, and pokeweed.

Control the weeds in your garden

In addition to culture practices, sometimes the assistance of chemicals is needed to control weed growth. In that case, there are several types of herbicides that can be used. Preemergence herbicides will affect seeds that are germinating. Since they are best used two to three weeks before the seeds start to grow, these work best to combat annual weeds.

Postmergence herbicides are used, as their prefix implies, after the weeds have sprouted. Since they must be absorbed through the leaves, this types of herbicide works best with a spray. These can be used at any time, but are most effective when the weed is still young and growing.

Selective postmergence herbicides are usually used to control annual, biennial and perennial broadleaf weeds, as they will not damage grass. But, they can kill trees, shrubs and flowers. These have to be used in proper conditions as well, with no rain in the forecast for two days to follow, air 60-80 degrees and no winds.

Finally, non-selective postmergence herbicides kill all types of weeds, and are best used to spot treat grassy weeds that are not affected by the selective herbicides.

Control the weeds in your lawn

Once you understand what is growing in your lawn and decide that it is unwanted, you can treat it and/or control it. Weeds can actually be controlled by your lawn care maintenance. If you maintain a dense and vigorously growing lawn, you are already combating the problem.

Weeds can be a sign of underlying problems in the environment beneath. So by just killing them, you are simply putting on a band-aid, not solving the problem. For example, some weeds grow in situations of compacted soil, such as knotweed.

You can also control the growth by taking better care of the grass, rather than focus on the weeds. You can raise or lower the mowing height, change the frequency of mowing and changing the amount of time between irrigating.

Also, you can increase or decrease application of fertilizer and aerify the soil. This will maintain better grass, thus keeping the growth dense and vigorous, which as discussed above, does not attract weeds.

It is important to scout the weed population throughout the year to assess the success of the weed management program.