The 6 Worst Lawn Weeds in Eau Claire, WI (and How to Get Rid of Them)

1. Crabgrass

Crabgrass is the most common lawn weed in Wisconsin. It is a summer annual grass, which germinates from seed each spring, grows aggressively through the heat, sets an enormous amount of seed, and dies at the first hard frost. Published estimates put seed production as high as 150,000 seeds per plant, and seed that does not germinate this year can germinate in future seasons.

What it looks like: leaf blades noticeably wider than your turf, growing in low clumps with stems running outward rather than upright.

How to control it: prevention is the whole game. Pre-emergent has to be down before soil temperatures hold around 55 degrees so the product is in place as seed germinates. Escapes still happen in thin areas and along pavement edges where soil warms first, and those can be spot-treated with a post-emergent. Most companies here make one spring application. We make two, early spring and late spring, because pre-emergent only stays active for roughly six to ten weeks and a single early application leaves the back half of the germination window uncovered.

2. Dandelion

A perennial with a deep taproot that spreads by wind-carried seed. The seed germinates readily and persists in the soil for a few years.

What it looks like: smooth, sharply toothed leaves in a flat rosette, bright yellow flowers, and round white seed heads.

How to control it: most people associate dandelions with spring, but a major germination flush happens in late summer and early fall. Fall is also the strongest treatment window, because the plant is moving carbohydrates down into its taproot and carries systemic herbicide with them, which kills the root rather than just the top. We use a specialty weed shield product designed to reduce how many emerge, and escapes can be treated with a broadleaf herbicide at other times of year.

3. Creeping Charlie, also called ground ivy

A tenacious perennial named for its creeping stems, which root at the nodes as they run. It spreads by those stems and by seed, favors shade and moisture, and moves into lawns that are already thin.

What it looks like: a low vine with round, scallop-edged leaves and small purple flowers, forming a dense mat.

How to control it: it resists many common broadleaf herbicides, which is the core problem. One or two plants can be pulled by hand. On a patch, hand pulling makes it worse, because every stem fragment left behind or dropped elsewhere in the lawn can root and start a new colony. We treat it with a specialty liquid product across multiple applications through the year, with fall applications doing the most work. Standard store-shelf products generally will not finish it.

4. Clover

White clover fixes its own nitrogen through root nodules, which is why it thrives in underfed lawns. It has a competitive advantage exactly where your grass has a nutritional disadvantage, so clover is as much a fertility signal as a weed problem.

What it looks like: three leaflets at the end of a stem and small round white or pink flower heads.

How to control it: feed the lawn and stop mowing it short. A dense, well-fertilized stand removes clover's edge and crowds it out. Established patches respond to broadleaf herbicide, but if the fertility problem is not corrected it returns.

5. Broadleaf plantain

A stubborn perennial that favors compacted soil, thin turf, moist shade, and areas with uneven irrigation. It has a shallow fibrous root system with a short central taproot and overwinters as a basal rosette.

What it looks like: medium green oval leaves with prominent parallel veins forming a flat rosette, with narrow flower spikes carrying dozens of tiny buds in late spring.

How to control it: remove the conditions it prefers. Core aerate in fall to relieve compaction, mow at three to four inches, seed thin areas, and fix uneven sprinkler coverage. Established plants respond to broadleaf herbicide, and fall treatment works best.

6. Annual bluegrass, or Poa annua

One of the most common grassy weeds in cool-season lawns. It germinates in late summer or early fall, grows through fall and the following spring, flowers heavily, then typically dies out when summer heat arrives, leaving thin or bare patches behind.

What it looks like: similar to Kentucky bluegrass but a lighter, yellower green, with a noticeably finer texture and a profusion of short seed heads early in the season, often below mowing height.

How to control it: it is difficult, because it is a grass growing among grasses. A fall pre-emergent application timed ahead of its late-summer germination is the most practical preventive step. On heavily infested areas, spot treatment with a non-selective herbicide while the plant is actively growing, followed by renovation and reseeding, is the remaining option. A dense, well-fed lawn with good drainage and correct mowing height is the long-term defense, because annual bluegrass establishes in wet, compacted, closely mown turf.

The best defense against all of them

Every weed above is easier to prevent than to remove, and a thick healthy stand of turf is the prevention.

Mow high

Cutting lower to take weeds down is counterproductive. Taller grass grows thicker, shades the soil surface so weed seed does not get the light and warmth it needs, and supports deeper roots. Mowing short heats the soil, which is what crabgrass seed is waiting for.

Water correctly

Both extremes favor weeds. About an inch per week including rainfall, delivered in one or two long cycles finishing in the early morning, builds the root system that lets grass outcompete them. A properly designed irrigation system makes that consistent.

Treat on the right calendar

Spring preventive timing follows soil temperature, which in Wisconsin puts the start anywhere from March to May depending on the year. Curative treatments run April through early October. Many of the worst spring weeds germinate the previous fall, so a program that stops in August gives up its most productive window.

Spot treat where that is enough

Crabgrass requires whole-lawn pre-emergent coverage because seed is distributed everywhere. Most broadleaf weeds do not. Treating only the plants present uses far less product, which is better for your yard and for everything downstream of it.

Expect some weeds anyway

No program removes 100 percent of weeds, and anyone claiming otherwise is not being honest. Herbicide commonly takes ten days or more to show results, and the goal is killing the plant rather than browning it off. We return for persistent escapes at no charge or catch them at the next visit, which is how our lawn care programs are structured.