As lawns green up, thoughts turn to crab grass. And dandelions. And creeping Charlie. And clover. And plantains.
These are the major enemies of Chicago-area greenswards, now preparing their attack. As you plan yours, know that there is only one all-purpose weapon in the battle: a lawn that is kept healthy and thick via good fertilization, watering and mowing.
“Good cultivation is key,” says Brian Levins, landscape maintenance account manager for ILT Vignocchi, a landscape firm based in Wauconda. “A thick, dense, well-rooted lawn will choke out most weeds.”
A lawn that’s cropped close to the ground can’t shade out weed seeds, so instead, mow to about 3 to 3 1/2 inches. Grass that’s under-watered will go thin and leave room for weeds to get a toehold; but if it’s over-watered, it may develop weak, shallow roots, no match for the bullies.
Beyond keeping the lawn in fighting shape, there are specialized ways to combat the Big Five. Here are experts’ tips:
– Crab grass: The worst of the grassy weeds, crab grass is that stuff that crops up in big, sprawling tufts on bare spots in the lawn, usually in dry and hot times. Large crab grass has hairy stems; smooth crab grass doesn’t, and its blades have a purplish cast.
To stop both kinds before they can sprout, buy a pre-emergent lawn treatment whose label says it fights grassy weeds including crab grass. A pre-emergent labeled for broadleaf weeds will not do it.
The best time to apply is when temperatures have been consistently in the 60s for several days, typically by late April or early May, advises Ken Smiciklas, an associate professor of plant science at Illinois State University in Normal. As with all lawn products, follow the instructions on the label carefully and don’t convince yourself that overdosing the lawn will work better.
Crab grass, Smiciklas explains, is an annual–it sprouts new each year from the previous year’s seed. Hand-pulling any surviving plants will prevent them from leaving seed for next year.
– Creeping Charlie: It also goes under the aliases ground ivy and wild violet. Creeping Charlie is an insidious vine whose ground-hugging stems send out roots, making it difficult to vanquish. Its crinkly leaves and tiny purple blooms are pretty, but make no mistake–it’s greedy for space. In shady areas, it easily defeats grass that wasn’t bred for shade.
Sprays and granular products are available, but Smiciklas believes this one is best attacked mano a mano. “Nothing beats hand-pulling, really,” he says. “In a suburban yard that’s a typical size, you won’t have too much to get it all pretty easily.”
The vine pulls up handily; the hard part is getting the roots out too. Be sure to follow each creeping vine to its origin and pull it all out–and deposit it directly into a bucket or bag. Don Ferreri, golf course superintendent at Seven Bridges Golf Club in Woodridge, points out that little remnants of creeping Charlie accidentally left on the lawn after they’ve been pulled can root.
– Dandelions: There’s one thing you can’t deny about dandelions: They’re prolific. Allow a few to thrive in your yard this year and they’ll scatter countless progeny for next year.
Dandelions also are best controlled with a pre-emergent treatment–but one labeled for broadleaf weeds. A well-proven organic alternative, corn gluten meal, is available in many area nurseries now.
Once dandelions have shown their buttery faces, you can wipe them out one of two ways. Use a post-emergent, targeted spray (sprayed directly onto the foliage) that is labeled for dandelions. But don’t use glyphosate (Round-Up) or any other all-purpose herbicide, because it will kill any grass upon which it lands.
Hand-pulling is also very effective, if done right. Dandelions are perennials with strong taproots from which they’ll sprout repeatedly, “so you have to make sure you get it, not just the stem and leaves,” emphasizes Ferreri. For moderate-size plants, use a dandelion weeder that pokes under the plant and pops the root out. For large plants, scrape away nearby grass with a gardening fork so you expose the taproot as it breaks the surface. Grab that securely and pull. Or dig the entire root out and replace it with soil and a tiny plug of sod.
– Plantain: With its flat leaves, either round or lance-shaped, and its ankle-high bloom spike, plantain definitely looks out of place in the emerald carpet of a lawn. It usually shows up in compacted soil, Ferreri notes.
Compaction can be the result of high foot traffic or low organic content. You may not be able to cut down the traffic, but you can add organic material to your lawn via compost and other top-dressings. And you can aerate to get water and air to the roots of the grass plants.
If the weeds occur, broadleaf post-emergents labeled for plantains will do the trick, but hand-pulling is easy. When the soil is moist, slip your fingers beneath the leaves and grasp the stem. It will pull right out.
Like dandelions, plantains sprout from old roots, so getting out the root–not just the above-ground part–is essential to reducing your plantain population.
– White clover: White clover often goes unnoticed until it blooms–and then you can’t miss it. The little round leaves fit right in among blades of grass, but the cottony white flowers scream to be noticed.
What you’re actually hearing, Smiciklas says, is the soil itself asking to be fed. “White clover is a sign of low soil fertility,” he says. “Address the fertility issue and grass will be able to compete better.”
Spreading a nutritious top-dressing, such as compost, over the lawn on a regular basis will do the trick.
That’s for the future, though. For white clover that’s showing this year, you’ll mostly just have to adjust. Clover is hard to remove by hand-pulling and hard to tackle with sprays–its waxy leaves resist most chemicals, Levins says.
So relax and watch the toddlers and bumblebees enjoy it.
