Broadleaf weed killer: what works and when to spray
A broadleaf weed killer is a selective herbicide that kills dandelions, clover, plantain and other wide-leaved weeds without killing lawn grass. For most lawns the best choice is a three-way mix of 2,4-D, MCPP and dicamba, sprayed on actively growing weeds in fall (or spring as a second chance), between about 65 and 85°F, on a calm day with no rain in the forecast.
Contents
What counts as a broadleaf weed?
Broadleaf weeds have wide leaves with a net of branching veins, unlike grass blades with parallel veins. Many have showy flowers. Common lawn examples:
- Perennials that come back from roots each year: dandelions, white clover, creeping Charlie, wild violets, plantain.
- Winter annuals that sprout in fall and flower in early spring: chickweed, henbit.
- Summer annuals that sprout in warm weather: spurge, purslane.
Not covered by broadleaf herbicides: grassy weeds such as crabgrass, sedges such as nutsedge, and moss. If you are unsure what you have, check our weed identification guide before you buy.
How broadleaf herbicides work
The classic broadleaf herbicides (2,4-D, MCPP, MCPA, dicamba and triclopyr) are growth regulators. They mimic a plant hormone and make broadleaf plants grow abnormally: stems twist, leaves curl and cup, and the plant eventually dies. They are systemic, moving through the plant to the roots, which is why they kill perennials that a contact spray only burns back. Lawn grasses process them differently, which makes these products selective.
No single ingredient controls every broadleaf weed. Iowa State University Extension notes that mixtures work best for that reason, which is why most lawn products combine two to four ingredients.
Common active ingredients
| Active ingredient | Strong on | Notes |
|---|---|---|
| 2,4-D | Dandelion, plantain and many common broadleaves | Backbone of most mixes; many 2,4-D products are not labeled for St. Augustinegrass, and centipedegrass tolerates only low rates |
| MCPP (mecoprop) | Chickweed, clover | Usually in mixes with 2,4-D and dicamba |
| Dicamba | Clover, chickweed and other harder-to-kill weeds | Taken up by tree and shrub roots; can volatilize in heat |
| Triclopyr | Creeping Charlie, wild violets, clover, oxalis | For cool-season lawns; injures St. Augustine, centipede and bermudagrass |
| Carfentrazone, sulfentrazone | Speed | Added to some mixes so weeds brown within days |
| Iron HEDTA | Dandelion, clover and other broadleaves | Iron-based contact product; perennials need repeat treatment |
Three-way mixes of 2,4-D, MCPP and dicamba are among the most common broadleaf weed control products for lawns. Read the active ingredients on the back of the label, not the name on the front, and use exactly what the label allows. In the United States, the label is the law.
When is the best time to spray broadleaf weeds?
Fall is best for perennial broadleaf weeds. In autumn, perennials move sugars from their leaves down to their roots to survive winter, and a systemic herbicide travels down with them. Iowa State University Extension names mid-September to early November as the best window in Iowa; farther south, the window runs later. For creeping Charlie, the same source recommends two applications about a month apart, starting in mid to late September.
Spring is the second window, once weeds are actively growing. Spraying spring dandelions often kills the tops but leaves more survivors than a fall treatment. On warm-season lawns, avoid broadleaf herbicides during spring green-up, when the turf is easily injured; Clemson Extension notes this especially for centipedegrass and St. Augustinegrass.
Temperature matters. Most broadleaf weeds are best treated when air temperatures are between 65 and 85°F. Above that, turf injury is more likely. Iowa State University Extension advises not to spray when temperatures are forecast to exceed 85°F within 24 hours.
How to apply a broadleaf weed killer
- Skip mowingDon't mow for two to three days before treating, so weeds have plenty of leaf to absorb the product. Wait three or four days after treating before you mow again.
- Pick the right dayCalm (wind under about 5 mph), no rain forecast for 24 hours or the rain-free period on your label, and temperatures in the 65 to 85°F range.
- Liquid: spot-sprayUse a pump sprayer at low pressure with a nozzle that makes coarse droplets. Wet the weed leaves; don't drench the soil.
- Granular: wet the leaves firstGranules work through the leaves, so apply when weeds are wet with dew or after a light watering, and don't water in until the label allows.
- Repeat if the label allowsTough perennials such as violets and creeping Charlie often need a second application, at the interval on the label.
Drift, volatility and tree roots
Broadleaf herbicides kill broadleaf plants, and your tomatoes, roses and shrubs are broadleaf plants too. Three ways they reach plants you didn't target:
- Drift: fine spray droplets carried by wind. Spray on calm days, low to the ground, with coarse droplets.
- Volatility: some formulations turn to vapor after application, especially in hot weather, and move with the air. Ester forms of 2,4-D are more prone to this than amine forms, and dicamba can volatilize too. Another reason to stay under 85°F.
- Root uptake: tree roots spread far beyond the canopy and run under the lawn. Purdue University Extension notes that dicamba, unlike 2,4-D and MCPP, can enter tree roots and has caused damage. Don't broadcast dicamba products, including weed-and-feed, over the root zones of trees and shrubs; spot-treat there instead, or pull the weeds.
Grass clippings: many broadleaf herbicide labels say not to use clippings from a treated lawn as mulch or compost around vegetables and flowers for a set number of mowings. Check yours before you bag clippings for the garden.
Is it safe for your grass?
Cool-season lawns of Kentucky bluegrass, tall fescue and perennial ryegrass tolerate most broadleaf mixes. In the South, St. Augustinegrass and centipedegrass are sensitive to several of the usual ingredients, so buy a product that specifically lists them. Bermudagrass and zoysiagrass handle most three-way mixes. On new lawns, wait until the grass has been mowed a few times, or as long as the label says, before using any broadleaf weed killer. Our guide to choosing a weed killer for lawns has a grass-by-grass table.
Common mistakes
- Spraying in summer heat: more turf injury, more vapor drift, weaker control.
- Mowing right before or right after, which removes the leaf surface the herbicide needs.
- Using a dicamba product under trees and shrubs.
- Expecting it to kill crabgrass or nutsedge.
- Spraying once in spring and giving up on violets or creeping Charlie, which usually need fall treatments, often two.
- Leaving the lawn thin afterward. Overseed bare spots and mow high so new weeds don't fill the gaps.
Broadleaf weeds are only part of the picture. Our lawn weeds guide shows how to prevent them with mowing, watering and feeding, and the weed control calendar tells you what to spray when.
FAQ
What is the best broadleaf weed killer for lawns?
For most lawns, a three-way mix of 2,4-D, MCPP (mecoprop) and dicamba controls the widest range of broadleaf weeds, from dandelions to clover. For hard-to-kill weeds such as creeping Charlie and wild violets, a product containing triclopyr works better on cool-season lawns. Pick one that lists your weed and your grass type on the label.
Is broadleaf weed killer safe for grass?
Broadleaf herbicides are selective: at the label rate they kill broadleaf plants and spare the lawn grasses listed on the label. Turf can still be injured if you spray above about 85°F, during spring green-up of warm-season grass, on new seedlings, or on a sensitive grass such as St. Augustinegrass or centipedegrass.
What herbicide kills creeping Charlie?
Triclopyr, alone or in a mix, is the usual choice for creeping Charlie in cool-season lawns. Iowa State University Extension recommends a first application in mid to late September and a second about a month later. See our full creeping Charlie guide.
How long after spraying broadleaf weed killer can it rain?
It depends on the product, so check the rain-free period on the label. Iowa State University Extension advises not to apply when rain is forecast within 24 hours. Granular products are the exception in one way: they need wet leaves at application, but should not be watered in until the label says so.
Is there a pre-emergent for broadleaf weeds?
Yes. Isoxaben is a pre-emergent labeled for many annual broadleaf weeds in established lawns, and several crabgrass pre-emergents also list some small-seeded broadleaf weeds on their labels. Pre-emergents do nothing to perennial broadleaf weeds already growing from roots, such as dandelion or clover.
How long does broadleaf weed killer take to work?
Growth regulator herbicides such as 2,4-D and dicamba usually cause twisting and curling within days, but complete kill of perennial weeds can take a couple of weeks or more. Some products add a fast-acting ingredient such as carfentrazone or sulfentrazone so you see browning sooner.
Related
- Lawn weed killerWeed killer for lawns, explained: selective vs non-selective, pre- vs post-emergent, liquid vs granular, grass type limits and the right ingredient by weed.
- DandelionsHow to get rid of dandelions in your lawn: dig out the taproot, spot-spray a broadleaf killer in fall, and thicken the grass so new seeds can’t take hold.
- CloverHow to get rid of clover in lawn grass: pull small patches, feed the turf, spot-spray the right active ingredient in fall — or decide to keep it.
- Creeping CharlieCreeping Charlie (ground ivy) is one of the hardest lawn weeds to kill. What works: triclopyr in fall after frost, pulling runners, more light, thicker grass.
- Wild violetsHow to get rid of wild violets in a lawn: dig out the rhizomes, spot-spray triclopyr in spring and fall, repeat for more than one season and thicken the grass.
Updated October 3, 2026