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, control, 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 killer, find out what those weeds are.

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

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, 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!

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 previously mentioned are safe for most cool season grasses. But a non-selective herbicide such as Avenger Organic will kill everything is 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

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

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2 thoughts on “How to Kill & Control Weeds in Your Lawn”

  1. We are reseeding our lawn in some spots and just overseeding it in other areas due to extensive crabgrass, clover and moss invasion. We applied Moss Out and Round up (safe for lawns) in late July. We just finished thatching and scarifying the lawn with a Sun Joe machine and then hand raked enormous amounts of moss out of the lawn. Because of the extensive amount of moss, we spread ferrous sulfate over the lawn and watered well. It is now mid-Aug & I would like to know if putting a pre-emergent/post-emergent herbicide such as Dimension on the lawn would help with getting rid of the crabgrass & clover. I am afraid if I wait until Spring to apply the Dimension, the crabgrass & clover will have re emerged & taken over the lawn again. We want to reseed/overseed in late Sept. and we live in the Portland Oregon area.

    Reply
    • Hi Judy. Dimension has some post emergent qualities for young crabgrass, but you should not apply this if you are thinking of overseeding. You can safely kill crabgrass now with something like quinclorac, and seed shortly after. Crabgrass is an annual grass and will not germinate until next spring as soil temps begin to approach 55 degrees. Applying a preemergent will do nothing for next year’s crabgrass. Check your soil temps and make sure you apply Prodiamine before soil temps hit 55 degrees. Apply a second application about 2 months after your first and you should have good coverage against crabgrass all season. (Here in MA, I apply 5 lbs. Prodiamine per 1,000 sq. ft. in early April (9 lbs. per 1,000 annual max) followed by a full application of Dimension in early June.

      Clover is a sign that your lawn may be undernourished. Make sure your feeding your lawn regularly. The quinclorac will also kill the clover.

      Hope this helps!

      Reply

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