How to Kill & Control Weeds in Your Lawn

So your lawn is full of weeds and looking for a DIY how-to kill and control weeds in your yard? Violet, dandelion, clover, creeping charlie, and crabgrass – the list of nasty cool-season broadleaf weeds (dandelion) and grassy weeds (crabgrass) here in the Northeast is a mile long, and they’re all rearing their ugly heads now in the spring. April showers bring May flowers… and weeds galore!

Follow these steps to help kill weeds, control weeds, and prevent weeds in your lawn. For crabgrass, read The 5 Best Crabgrass Killers and How to Prevent & Kill Crabgrass in Lawns. 

Weed Identification

The very first step to getting rid of weeds in your lawn is first identifying what they are. Treating the wrong weeds can not only be ineffective, but could possibly harm your good turf. So before reaching for any herbicide or weed killers, find out what those weeds are.

Start with these two links from UMASS, then do some more Google searches:

• Weeds Fact Sheet
• Weed Herbarium

How To Get Rid of Weeds Without Killing Grass

This list the order in which I recommend. I follow Integrated Pest Management (IPM) as much as possible, and would of course rather prevent weeds from showing up than to throw down chemicals.

• Prevention. The best way to get rid of weed in your lawn is to prevent them in the first place. Applying a pre-emergent such as Prodiamine in the early spring is (and should be) first on everyone’s lawn care schedule program. As ground temperatures begin to hit ~50 degrees is your first split application. Follow up with a second application approximately ~45 days later as the ground temperatures approach 65-70 degrees.
• Maintain a healthy lawn. Thick, healthy turf will make it very difficult for weeds to thrive. Overcrowding can “choke out” the competing weeds, and the tall thick grass will shade weeds, limiting photosynthesis.
• Continue to Mow. Cutting off the leaves of weeds will stunt their growth. Like all plants, they soak in the sunlight from their (broad) leaves for photosynthesis to occur. Cutting them down will limit photosynthesis and slow the weeds’ growth.
• Don’t Always Reach for Chemicals. If you’re lawn isn’t infested, then good old fashioned elbow grease does the trick. Grab some gardening gloves, hand weeder, or a 4-claw weeder, and pull them up by hand. Make sure you pull the taproot, too!
• Follow Integrated Pest Management, defined by UC IPM:

IPM is an ecosystem-based strategy that focuses on long-term prevention of pests or their damage through a combination of techniques such as biological control, habitat manipulation, modification of cultural practices, and use of resistant varieties. Pesticides are used only after monitoring indicates they are needed according to established guidelines, and treatments are made with the goal of removing only the target organism. Pest control materials are selected and applied in a manner that minimizes risks to human health, beneficial and nontarget organisms, and the environment.

• Spot Spray. “Weed & Feed” are generally a Step 2 in a 4 Step fertilization plan, but avoid these especially if you don’t have a lawn full of weeds. Spot spray weeds in the spring and fall. Read the labels of the weed killers to ensure you’re applying at the right times (of the day and season) and rates . Spray weed killer where you see the weeds – don’t spray where you don’t.

Best Time of Day to Spray Weeds

• Always read the label of the herbicide and weed killers that you’re spraying.
• Generally in the morning or evenings are the best times to kill weeds, as the air temps are cooler.
• Avoid spraying during the daytime especially in the heat of the summer (over 80 degrees).

Wear Personal Protection Equipment (PPE)

Safety is our top concern. If there’s one takeaway here, read the label. Check when it’s safe for children and pets to return to the sprayed areas. And wear your PPE. These include:

• Hat with a brim
• Protective eyewear
• Long sleeve shirt
• Pants
• Rubber boots
• Gloves – such as disposable nitrile

Best Weed Killers for Cool Season Lawns

Generally, the weeds that we see here in the Northeast can be controlled with chemicals such as, but not limited to, 2,4-D, dicamba, and quinclorac. Once you’ve identified your problem weeds:

• Make sure that the product has your target pest on the label!

For example, Quinclorac is effective against dandelion, where SpeedZone is effective against spurge and plantain.

• Make sure that the product is safe for your cool-season grass type(s)!

Selective herbicides – such as the two weed killers previously mentioned – are safe for most cool-season grasses. But a non-selective herbicide such as Avenger Organic will kill everything it touches – including your grass.

Get yourself a designated 1-gallon hand pump sprayer for herbicide use only. I use my 4-gallon backpack sprayer strictly for fertilizers, and hand can for selective herbicides only. 

Effective Products

• Tenacity
• Non-Ionic Surfactant (recommended for Tenacity)
• SpeedZone
• Bayer All In One Lawn Weed & Crabgrass Killer
  • More readily available including in big box stores
  • Comes in concentrate, spray bottle, and hose-end mix
  • Cheaper alternative
• 0-0-7 Crabrgass Control, 0.37% Prodimaine
  • Pre-emergent
• Liquid Prodiamine(generic Barricade)
  • Pre-emergent
• Avenger Weed Killer Concentrate
  • Non-Selective – will kill everything
• Fiskars 4-Claw Weeder
• Hand Weeder
• Chapin 1 Gallon Sprayer
• Nitrile Gloves (PPE)

I hope this information was helpful. Please share a comment or feel free to ask questions in the comments below. Thanks for reading!