How To Kill Weeds Without Killing Grass

For those of you who are ready to fight the good fight, here’s a step-by-step guide that will help you get rid of weeds when they start growing on your lawn. (For those of you who want a jump start before weeds become a problem, read our guide on How to Prevent Weeds from Growing.)

How to Get Rid of Weeds

Learn to Read Weeds

Sometimes weeds are a clue to soil or site problems. Correct them so your landscape favors lawn grasses and discourages weeds. For example, ground ivy grows best where the soil surface remains damp. It also thrives in areas too shady for good grass growth. So consider improving soil drainage by aerating—removing small cores of soil—if ground ivy is a problem. And, to allow more light to reach the surface of the soil, selectively remove tree branches in shady areas.

Hand-Weeding

Growing a healthy lawn with proper mowing and watering can keep weeds from sprouting. Here’s how to go after the weeds you have: Hand-weeding is still the best defense on small lawns where the number of weeds isn’t overwhelming. It’s most effective against annual broadleaf weeds. Pulling them while they’re young—before they flower and seed—is the simplest way to prevent them from spreading. Catching perennial weeds early is crucial. Dandelions, for example, develop deep taproots that are hard to pull once they mature. Yank the entire plant, including the root—any root pieces left underground will grow new plants. If new sprouts grow, pull them repeatedly to eventually starve and kill the weed. Weeding is easiest when the soil is moist. Tools like the dandelion digger help get at the root by probing deep into the soil. Once the weed is out, promptly reseed the bare spot; otherwise, new weeds will fill it in.

Pulling Weeds Permanently: Step 1

Perennial weeds such as dandelions should be pulled when they are young. When soil is moist, push a sharp spade or dandelion digger into the soil, angled downward toward the center of the plant, and loosen the soil around it.

Pulling Weeds Permanently: Step 2

Use the tool to pry the weed upward while pulling it; try not to break off the roots.

Pulling Weeds Permanently: Step 3

Once the weed and roots are out, smooth the soil, work in some compost, and patch the area with lawn seed. Keep the soil evenly moist until the grass is 1 inch high.

Pry Weeds From Paving with a Weeder

The Telescoping Crack Weeder ($9.95) from Lee Valley Tools removes grass and other weeds from crevices in patios and walkways. The L-shaped stainless-steel blade fits between bricks and other pavers to reach and scrape pesky plants. The aluminum handle adjusts from 28 to 45 in., which means you can weed kneeling or standing.

Off with their heads with a scuffle hoe

The scuffle hoe (also called an oscillating or action hoe) gets its names from the double-edged hinged blade that rocks back and forth with a push-pull motion. As it rocks, it slices weeds off at the crown. Repeated beheading depletes the weed roots of stored food and the plant dies. Shallow cultivation also avoids bringing more weed seeds to the surface where they can sprout.

Flame weeds

Gas-powered flamers kill weeds by heating them to the point that their cell walls burst. A single pass with the flamer, such as the Primus Gardener Weed Destroyer shown ($46.95), kills young annual weeds. They won’t look charred but will die within a few hours. Tough perennial weeds with deep roots usually regrow and require repeated treatments. Never use a flamer in an areas that’s dry and fire-prone, or in planting beds covered with flammable mulch.

Herbicides

Use herbicides as a last resort—when nothing else works on a particular weed or when your lawn is completely overrun. And follow directions carefully. Used incorrectly, herbicides can injure or kill turf and other desirable plants. If you use a herbicide, choose one that’s labeled as safe for the type of turf you’re growing and effective against the weeds you’ve got. The label states when and in which conditions to use the product. Some herbicides work only within a certain temperature range; others work only when applied at a specific time of year. Herbicides fall into three major categories: preeemergence herbicides, postemergence herbicides and weed-and-feed products.

Preemergence Herbicides

Preemergence herbicides kill germinating seeds before seedlings break through the soil. Crabgrass is the primary target. The most common preemergence herbicides are synthetic. Natural, nontoxic preemergence herbicides made from corn gluten are safer, though you might have to apply them for several seasons for them to be fully effective. Three quality products are Concern Weed Prevention Plus, WOW! and WeedzSTOP. A drawback to these and most other preemergence herbicides is that they kill germinating lawn seed. Check product labels carefully.

Postemergence Herbicides

Postemergence herbicides kill existing weeds that are actively growing. These come in two basic forms: contact and systemic. Contact herbicides kill only the part of the plant they touch. Most act quickly and work best against annual weeds. Systemic herbicides circulate inside the plant, killing the whole thing. They’re more effective than contact herbicides on perennial weeds, though repeat treatments might be needed. You also need to choose between selective and nonselective versions of systemic herbicides. Selective herbicides kill only certain weeds, while nonselective herbicides kill any green, growing plant, whether it’s a weed or not. Most broadleaf herbicides, including products like Weed-Away and Weed Warrior, are systemic and selective to kill broadleaf weeds only. They won’t kill weedy grasses. Glyphosate—the active ingredient in Roundup and other products—is an example of a systemic, nonselective herbicide that kills broadleaf weeds and weedy grasses. But because it also kills turf and other desirable plants, it’s safest to use it on your lawn when you want to kill an entire section and then replant it. Finale, in which the active ingredient is gluphosinate ammonium, is another nonselective used for this purpose. When using any postemergence herbicide, don’t apply them over your entire lawn, if possible. Instead, spot-treat isolated weeds or weedy patches.

Weed-and-Feed Products

Weed-and-feed products combine fertilizer and herbicides to do two jobs at once. But their promised labor savings can backfire if the recommended time for weed control doesn’t coincide with the best time and rates for fertilizing. Most also pose an herbicide-overdose risk when used for follow-up fertilizing. Corn gluten with added organic fertilizer is the safest weed-and-feed. Whichever herbicide you use, follow the directions. Address the causes of weeds at the same time to keep new ones from growing. And reseed the bare spots left by dead weeds. The bottom line in the war against weeds: Care for your lawn and apply only what it needs—and only when necessary.