So far, this series of monthly articles on gardening skills has focused on fundamentals of gardening. This month we widen the scope to take in a practice that, although it fits into the gardening category, is in some neighborhoods more like a fundamental responsibility of citizenship: keeping the lawn weed-free.
Past installments have pointed out that lawn-owners really ought to decide whether they can stand a dormant brown lawn or whether they will put up with the headaches of keeping it watered and green all summer. We also discussed the fine points of mowing the lawn, a seemingly inescapable rite of warm-weather weekends. It’s all part of supporting the lawn in its role as the green carpet upon which summer plays out. But as anyone with a lawn knows well, the one thing lawns need no help doing is sprouting unsightly weeds.
While it may sometimes seem like a futile enterprise, keeping weeds out of the grass is actually an investment in the lawn’s longevity. Many common lawn weeds are lovers of hot, dry conditions, precisely the kind of weather that is toughest on most turf grass. In other words, they’re perfectly poised to take over while the lawn is struggling. Turn your back on them for a few weeks, and you’ll soon see far less grass and far more ground ivy, plantains and chickweed than one person could ever pull out.
“The first line of defense against weeds is to grow healthy turf,” says Susan Grupp, a horticulture educator for the DuPage County unit of the University of Illinois Cooperative Extension Service. “Thick, healthy turf will out-compete weeds, but if the lawn is thin and struggling with drought stress or disease problems, then weeds see their chance to take over.”
Of course, Grupp acknowledges, maintaining a luxurious mat of green lawn demands almost constant effort, with careful attention to watering, mowing heights and disease control. Nevertheless, she says, “If you can figure out how to grow a stand of healthy grass, you’ll stop the weeds before they start.”
For those of us who live in the real world, where lawns droop and wither, lawn-weed control is a year-round process. It’s not impossible, but it does require work and good timing. “You can have a lawn without weeds,” says Dr. George Kapusta, a Southern Illinois University professor of weed control, “but you can’t get it just by asking. Effort goes into it.”
One season-long practice that aids the process is mowing the grass a bit higher than might seem perfect–2 1/2 to 3 inches. The turf will keep the soil shaded, discouraging most heat-loving weed seeds from germinating. The dreaded crab grass is particularly likely to be blocked out by taller turf grass.
Beyond that, there are two primary tools for keeping weeds out of lawns: herbicides and your hands. People who are turned off by herbicides can rely on their hands alone, but they’ll almost certainly have to lower their standards for the lawn–or make weed control a full-time job.
Even those who don’t mind using herbicides should plan to use only their hands and weeding implements in the high heat of summer, Grupp says. “You don’t get great weed control from herbicides if you apply them in warm weather, because the plants may not be growing actively, so they may not absorb–or translocate–the material as much as you’d like,” she says.
Aside from pre-emergent herbicides, which are specially formulated to halt weeds before they show up in spring, herbicides can be used most effectively in the late summer and early fall. Plan to make an application once daytime temperatures are safely below 85 degrees, usually from mid-September on. Grupp explains that “as it’s cooling down outside, plants are focused on moving water and other materials downward, toward the root system, instead of upward, toward the leaves and blooms, so the herbicide is going to be carried down very well.”
Dandelions, to name one hated variety of lawn weed, are best controlled with herbicide applied in fall, not spring.
Another good reason to apply herbicides in fall is that springtime is often dedicated to seeding bad patches of the lawn. Because herbicides can kill off new grass sprouts, there’s often no time to get a herbicide down before summer heats up. If there’s no seeding to do, a spring application can attack areas the fall round didn’t beat.
Any commercial brand of broadleaf herbicide will do the trick, Grupp and Kapusta both say, but all such products should be handled with care. Read and follow all instructions on the label–especially the part where it says not to apply herbicides on a windy day. “Drift is a serious problem,” Grupp says. “You set out to clean up your lawn and you end up devastating your perennials and annuals.”
Also, don’t apply an herbicide if rain is in the near-term forecast. Otherwise, the material will all wash away and you’ll have to start over.
Using a ground-level drop spreader can minimize drift, because the herbicide comes out of the equipment closer to the ground than if you use a hand-held spreader. It hasn’t as far to fall to the ground, so there’s less time for it to blow off course. For lawns that have few weeds, “spot applicators,” which aim a liquid herbicide directly onto one plant, are useful.
During the hot weeks of summer, leave the herbicide in the bag or bottle and pull weeds by hand.
Some common lawn weeds pull out easily if the ground is moist. They include plantains (flat leaves the size of a human ear, with tall, thin flower stalks) and chickweed (tiny glossy leaves and white flowers forming a snarled mat).
Others, such as dandelions and curly dock, will put up a fight. Dandelions send a sturdy taproot deep into the ground; pulling off the above-ground greenery without getting the root does no good. A new plant will form atop the root. Dig out the entire taproot using a small hand spade. Curly dock has slender oblong leaves almost like those on an elm tree, with the edges slightly ruffled. Its taproot can make a dandelion’s look wimpy, and it, too, must be dug out completely or it will sprout anew.
If pulling weeds is your idea of hell, you can always wait until fall and start the lawn on a rigorous herbicide regimen, but Kapusta, looking for the bright side, notes, “it’s a good workout, all that bending and stretching. You don’t need to spend a lot of money on a health club.”
