All About Lawn Weeds

Lawn weeds can be one of the more troubling aspects of lawn care. Most weeds are opportunistic and will take advantage of any weakness in the turf. Thinner areas of grass, grass that is mowed too short and even infertile soil make perfect opportunities for weeds to grow. Weeds compete with turfgrass for space, nutrients and water. Many weeds grow much faster than turfgrass and can quickly get out of control if measures are not taken to stop them. At the very least, they detract from the quality and appearance of your lawn.

The conditions that allowed for weeds to flourish must be corrected or they will continually be a problem. Lawns must be maintained in a way that promotes a healthy lawn, while discouraging lawn weeds. There are many ways to accomplish this. Some types of grasses can be overseeded to thicken the turf. You should develop a sound fertilization program based on the needs and use of the grass. It is also important to mow the lawn at the highest recommended level. These tactics will hinder weed germination and growth since most weeds cannot compete with a thick lawn.

If the lawn is in serious decline, it may take a couple of years to begin seeing a quality turf and a major reduction in weed growth. There are not too many shortcuts to producing a nice lawn. For the most part, the methods are the same for homeowners and professionals alike.

The last resort for weed control is to use chemical herbicides. However, as lawn quality improves, lawn weeds and herbicide use will be greatly reduced.

While there are herbicides labeled for the majority of broadleaf lawn weeds, this is not the case with some grassy weeds. Since many desirable grasses and grassy weeds are genetically similar, there are fewer herbicides that can effectively control one type of grass without harming other types. Fortunately, some of the more common grassy weeds, including crabgrass, foxtails and sedges can be controlled using selective herbicides. Remember, before using any herbicide, the label must first be read carefully and completely. The label will contain instructions on how to use the product safely and correctly.

Weed Classifications

A weed is classified as any plant that is growing where it is not wanted. Even turfgrasses can be considered a weed when they have spread into planters or into neighboring yards.

The two main weed categories are broadleaf weeds (dicots) and grassy weeds (monocots). When these plants first emerge from the soil after germination, monocots will emerge as a single blade while dicots emerge from the soil with two blades.

There is also another group of lawn weeds called “sedges” that are related to grasses. These look very similar to grasses, but are easily distinguished by their triangular stems.

The broadleaf category contains some of the most commonly recognized weed types. Within this group are plants such as dandelions, plantains, chickweed, clover and many other species.

Grassy weeds contain some of the more difficult weeds to control. They include annual bluegrass, crabgrass, foxtails, goosegrass, barnyard grass and sandbur, to name just a few. The small groups of sedges contain a few varieties such as purple nutsedge, yellow nutsedge and also hurricanegrass.

Annual and perennial weed types

Many weeds are annuals and have a one year life cycle. This means they will germinate from seed, mature and die within twelve months. There are summer annuals and winter annuals. Winter annuals will germinate from seed in the fall, survive the winter, mature in the spring and die as the air and soil temperatures heat up in late spring or early summer. Annual bluegrass, common chickweed, and henbit are examples of winter annuals.

Summer annuals will germinate from seed in late spring, mature and die in the fall with the first killing frost. Crabgrass, sandbur, black medic, prostrate spurge and carpetweed are examples of summer annuals.

Since annuals die each year their survival depends on the seed produced the previous year. Most annuals produce large volumes of tiny seed. These small seeds are easily blown and worked into the soil.

With perennial weeds, their survival is attributed to well developed root systems, rhizomes and stolon production, or seed. Some weeds will use a combination of all three.

Some weeds are capable of growing in compacted, rocky or nutrient depleted soils. They can survive under conditions that would kill other plant life.

Many weeds have very unique methods of ensuring their survival. Oxalis (Yellow Wood Sorrel), for example, produces seed pods that explode when they are touched, spraying tiny seeds for several feet in all directions. Dandelion tap roots can extend a foot into the soil. Not only that, but even if you cut the root into a dozen pieces and plant each piece, they would produce a dozen new dandelion plants. This means, if you attempt to rid your lawn of dandelions by pulling them up by hand, any portion of the root left in the soil will produce a new plant.

Quackgrass is a grassy weed that emits chemicals from its roots that harms the other plants around it. This helps quackgrass to get established and gain the upper hand. These and other unique qualities of lawn weeds are part of the reason lawn weeds are so common and wide spread.

How this section can help you

The pages throughout this lawn weed section will help you identify common lawn weeds and the best methods of controlling them. When you remember about 75% of weed control is non-chemical, it makes weed control much safer and easier in the long run. Cultural practices that emphasize a thick, vigorous turf will leave little room for lawn weeds to germinate and grow.