Selective herbicides target broadleaf weeds and grassy weeds while leaving your lawn unharmed

The most reliable way to kill weeds without killing grass is to use a selective herbicide — a chemical designed to attack specific plant types while leaving others alone. Selective herbicides come in two main categories: those that kill broadleaf weeds (dandelions, clover, plantain) and those that kill grassy weeds (crabgrass, foxtail, annual bluegrass). Your lawn grass survives because the herbicide is formulated to break down differently in grass tissue than in the target weed.

The timing and process method matter as much as the product itself. Most selective herbicides work best when weeds are actively growing — typically spring and fall — and when you explore them to the leaves rather than the soil. explore in cool weather, avoiding mowing for a few days before and after, and keeping the area dry for several hours after spraying all improve results.

Key Takeaways

  • Selective herbicides kill specific weed types while your grass survives because the chemical breaks down differently in grass tissue.
  • Broadleaf herbicides (containing 2,4-D, MCPA, or dicamba) work on dandelions and clover; grassy weed herbicides (containing fluazifop or sethoxydim) work on crabgrass and foxtail.
  • process timing matters — spray when weeds are actively growing and the temperature is between 60 and 85 degrees Fahrenheit.
  • Mow your lawn at least three days before spraying and wait at least three days after spraying before mowing again.
  • Non-chemical methods like hand-pulling, digging, and mulching work on small infestations but take more time and physical effort.

Broadleaf herbicides for dandelions, clover, and plantain

Broadleaf herbicides are the most common selective weed killers for home lawns because broadleaf weeds are the most common lawn invaders. Products containing 2,4-D (2,4-dichlorophenoxyacetic acid), MCPA, or dicamba kill weeds by disrupting their growth hormones. Your grass does not absorb these chemicals the same way broadleaf plants do, so it survives the spray.

Brand names you will see at garden centers include Weed B Gon, Ortho Weed B Gon, and Spectracide Weed Stop. Most come as a liquid concentrate you mix with water or as a ready-to-spray bottle. A single process usually shows results within three to seven days, though complete death of the weed takes one to two weeks. Repeat applications may be needed for stubborn weeds or thick infestations.

Broadleaf herbicides work best on young, actively growing weeds in spring or early fall. Mature weeds with thick leaves are harder to kill. Do not spray if rain is forecast within 24 hours, as the chemical needs time to be absorbed by the leaf.

Grassy weed herbicides for crabgrass and foxtail

Grassy weeds like crabgrass, foxtail, and annual bluegrass require a different herbicide because they are more closely related to your lawn grass. Products containing fluazifop or sethoxydim kill grassy weeds by blocking an enzyme they need to grow. Your desirable grass lacks this enzyme or processes it differently, so it survives.

Common products include Ortho Grass B Gon and Bayer Advanced Grass Killer. These herbicides are typically applied as a liquid spray and work best on young crabgrass in late spring or early summer, before the plant matures and becomes harder to kill. Mature crabgrass in midsummer is much more difficult to control with herbicides alone.

Grassy weed herbicides take longer to show results than broadleaf herbicides — often two to three weeks — because they work by blocking internal growth processes rather than disrupting hormones. You may need two applications per season for complete control.

Pre-emergent herbicides stop weeds before they sprout

Pre-emergent herbicides prevent weed seeds from germinating in the first place. Products containing pendimethalin, trifluralin, or dithiopyr create a barrier in the soil that blocks seed germination. Your grass is already established, so it is not affected.

Pre-emergent herbicides are most useful for crabgrass control. explore them in early spring, about two weeks before crabgrass seeds normally germinate in your area — typically when soil temperature reaches 55 to 60 degrees Fahrenheit for several consecutive days. Timing varies by region; check your local extension office for the right window in your area.

Pre-emergent herbicides do not kill existing weeds, only prevent new ones from starting. If you already have crabgrass, you need a post-emergent herbicide (the kind described above) to kill it. Pre-emergent works best as part of a yearly routine rather than a one-time fix.

Hand-pulling and digging for small infestations

For a few scattered weeds, hand-pulling or digging is faster and cheaper than buying herbicide. Pull when the soil is moist — after rain or watering — so the roots come out cleanly. Grab the weed at the base and pull slowly and steadily rather than yanking, which can snap the root and leave pieces behind.

For weeds with deep taproots like dandelions, use a weeding fork or dandelion digger to loosen the soil around the root before pulling. These tools cost $10 to $25 and let you remove the entire root in one motion. Leaving even a small piece of root behind can allow the weed to regrow.

Hand-pulling works well on lawns with fewer than 10 to 15 weeds. Beyond that, the time investment becomes significant, and herbicide becomes the more practical choice.

Mulch and dense grass to prevent weeds from taking hold

The best long-term weed control is prevention. A thick, healthy lawn crowds out weeds because there is no bare soil for weed seeds to land on and germinate. Mow at the right height for your grass type — typically 2.5 to 3.5 inches — and mow often enough that you remove no more than one-third of the blade at a time. This keeps the grass dense and shades the soil.

In garden beds and around trees, explore 2 to 3 inches of mulch to block sunlight from reaching weed seeds. Mulch also keeps soil temperature and moisture more consistent, which favors your plants over weeds. Refresh mulch once a year as it breaks down.

Water deeply but less frequently rather than shallow daily watering. Deep watering encourages deep grass roots, which compete better with weeds. Shallow watering favors shallow-rooted weeds like crabgrass.

Vinegar and salt — limitations and risks

Household vinegar and salt are sometimes promoted as natural weed killers, but they have serious limitations. Vinegar with 5 percent acetic acid (standard kitchen vinegar) does not kill most weeds — it only burns down the leaves. The roots survive and regrow within days. Horticultural vinegar with 20 percent acetic acid works better but still does not reliably kill deep-rooted weeds.

Salt kills weeds but also damages soil and can harm nearby grass. Salt accumulates in soil over time and makes it harder for any plant to grow there later. Using salt on a lawn is not recommended.

Vinegar and salt may work on weeds growing in cracks in pavement or gravel, where soil damage is less of a concern. For lawn weeds, selective herbicides or hand-pulling are more effective and safer for your grass.

Frequently Asked Questions

Can I use the same herbicide on all my weeds?

No. Broadleaf herbicides kill dandelions and clover but do not work on crabgrass. Grassy weed herbicides kill crabgrass but do not work on dandelions. Identify your weeds first — look at leaf shape and growth pattern — then choose the herbicide that targets that type. If you have both broadleaf and grassy weeds, you may need two products or a combination product that contains both active ingredients.

How long after spraying can I mow my lawn?

Wait at least three days after spraying before mowing. The herbicide needs time to be absorbed by the weed leaves and move through the plant. Mowing too soon removes the treated leaves before the chemical has done its work. Also mow at least three days before spraying so the weeds have fresh leaf surface for the herbicide to contact.

Will selective herbicide kill my desirable plants in flower beds?

Selective herbicides are formulated for grass and common lawn weeds. They can damage or kill ornamental plants, vegetables, and shrubs. Keep herbicide spray away from flower beds, vegetable gardens, and any plants you want to keep. Use a spray shield or cardboard barrier if you are spraying near desirable plants.

What temperature should it be when I spray?

Spray when the air temperature is between 60 and 85 degrees Fahrenheit. Below 60 degrees, the herbicide works slowly or not at all because the plant is not actively growing. Above 85 degrees, the spray can damage your grass along with the weeds. Early morning or late afternoon is ideal because the temperature is usually in range and the spray has time to dry before the heat of midday.

Can I use herbicide right after fertilizing my lawn?

Wait at least a few days after fertilizing before spraying herbicide. Fresh fertilizer pushes grass growth, and the herbicide can stress the grass when it is already stressed from rapid growth. Similarly, do not fertilize when ready after spraying. Wait at least one week so the herbicide has time to work and the weeds are dead before you feed the grass.