As winter approaches, your lawn management priorities shift. While mowing and irrigation schedules slow, there is still plenty to be done. Fall is one of those times of the year when you have to be on the lookout for weeds in clients’ lawns. Relax your vigilance in the cooler, shorter days of the fall and your customers can expect the wrong kind of green next spring: weeds.

Customers hate weeds. That’s why they hire you in the first place. If they see weeds in the lawns that you’ve been treating, they will not be happy. Unhappy lawn care customers soon become former lawn care customers.

Jack Robertson, Robertson Lawn Care in Springfield, Illinois, has an enviable record for managing weeds and keeping customers from season to season. Robertson laughingly refers to “snow” as his customers’ most unwelcome winter weed. No wonder he’s such a fun guy to be around. But, there are other weeds, he admits: dandelions and clover being two of the most common culprits.

Robertson says you must be able to identify and also understand the life cycle of weeds if you want to control them. Learning about them is not so difficult if you devote time to it and learn the basics.

For example, annual weeds sprout from seeds, grow, flower and die all in one year. Perennials come back year after year. Both annuals and perennials can be further classified as grassy or broadleaf weeds.

PHOTO: GREG HUME

Grassy weeds are monocots. They’re ugly, off color and they crowd fine turf by robbing it of nutrients and sunlight. Grassy weeds include crabgrass, foxtail and goosegrass, which are annual weeds. Common perennial grasses include bermudagrass (in cool-season lawns), nimblewill, quackgrass and orchard grass. Applying a preemergent herbicide at the proper time each spring usually provides good control of annual grassy weeds. It may take a contact herbicide applied in the summer to knock down perennial grassy weeds.

Winter weed no. 1: dandelion

In the fall, you will mainly be dealing with broadleaf weeds, such as dandelions, which are dicots. Although there are more than 40 species of dandelion, Taraxacum officinale is the most widespread cultivar. (The dandelion is an introduced species, brought from Europe by colonials for use as potherb and as a medicinal plant.)

Dandelions grow best in full sun in moist areas. Dandelion strong taproots are capable of penetrating the soil 10 to 15 feet deep, but in most lawns are usually only about 6 to 18 inches long. Buds grow from the top of the root, even if it is cut down to soil level. In addition, sections of root as small as an inch can produce new plants.

PHOTO: WHITNEY CRANSHAW, COLORADO STATE, BUGWOOD.ORG 

The leaves of the plant form a rosette, and can vary from 2 to 14 inches long. The margins of the leaves are serrated, and were thought to look like a lion’s tooth, which gave the plant its name (dent-de-lion means tooth of the lion in French.)

Flowers of this too-familiar plant are yellow and occur as soon as the plant is established, then quickly form the “puffballs” that spread the seed. Since dandelion plants can live for many years, if they remain untreated, it doesn’t take long for them to cover a lawn. Also, since the seeds can be blown in from miles away, there will probably always be new plants sprouting.

“There is no better time to control dandelions than in fall,” says Robertson. He uses a common three-way herbicide. “We do an application in September or October, then in November again if weeds are present.”

Winter weed no. 2: clover

Clover is another common weed in cool-season lawns. The dense, spreading plants can crowd out desirable turfgrasses. Clover’s creeping stems multiply across the surface of the soil and its rhizomes (basically underground stems) do the same below the soil surface. Clover blossoms also attract bees.

The clover species that is the peskiest in cool-season grasses is a member of the Trifolium species. White clover, T. repens, is probably more common, but strawberry clover, T. fragiferum, can also become a pest.

Seed mixes containing clover are once again on the market, and have become more popular as concerns for the environment grow. Strawberry clover is generally the species that is used. It can be robust and aggressive and although it has pink flowers, they are not as showy as white clover flowers.

PHOTO: FOREST AND KIM STARR

Robertson controls clover in the fall using the same three-way product as he uses on dandelions. “It usually will take care of the dandelions in one application in September or October, but we often come back in November to finish off the clover,” he says.

Of course, like with any pest, the best defense against weeds is a strong, healthy turf.

“What we basically advocate is Integrated Pest Control (IPM),” Robertson points out. “You really want a strong, healthy turf, and a regular fertilization program can really help you achieve that.”

That, of course, means applying the correct amount of fertilizer at the optimum time in the fall. “We had such a rainy summer that the nitrogen is pretty much used up,” says Robertson. “We will be coming back in the fall to put down fertilizer to be sure that the turf can grow some vigorous roots before the soil cools down completely. We will fertilize all the way until the first part of December or so. That makes a dense turf that can resist weed infestations.”

“Usually we are cooling off at the end of September, but this year, cool temperatures and plenty of rain made the fall weeds pop up earlier,” he adds.

Another tool in Robertson’s bag is overseeding. Getting grass to grow in bare spots and thickening weak areas on lawns discourages weed infestations. “Fall seeding is a big part of our overall program,” he notes. “Even if the seed doesn’t sprout before the cold, you get a jump-start in the spring,” he explains.

Because of the differences in soils, exposure and temperatures, lawns in different regions of the country are plagued with different weed species. Your local cooperative extension turf expert is an excellent resource for weed information. Chemical companies that market and sell herbicides to the industry also have online identification guides that can help you decide on a course of treatment.

The most important take-away when it comes to weed control tasks in the fall is to do them.

“Take care of problems now,” Robertson cautions. “Don’t wait until spring. I see many newcomers to the business make that mistake. Fertilization and weed control in the fall will make a big difference come spring.”