Killing lawn weeds can be very simple if you stay away from the products and practices that are a waste of time and money.
Broadleaf weeds can spread rapidly and suffocate your lawn. The longer you wait to combat lawn weeds, the harder it is to defeat them. If you want a green, uniform lawn, then managing lawn weeds should be a big part of your lawn care program.
The main problem I have with fertilizer companies and their step programs is they convince you that the best way to kill weeds that are already established is to apply one of their fertilizer and granular herbicide mixtures.
In my experience these products very rarely work. While companies like to sell you the convenience of fertilizing and controlling established weeds with the same application, it’s not the best way.
If you already have broadleaf weeds in your lawn it is very unlikely that one of these mixes will kill them.
Why Don’t Granular Herbicides Work on Established Weeds?
Granular post-emergent herbicides are herbicides you apply to established weeds. Granular post emergent herbicides are commonly found in products like Weed & Feed, or other 4 step programs that fertilizer companies promote.
Under perfect conditions these products sometimes work. But perfect conditions are hard to come by.
For starters the lawn needs to be a little wet to get the granular herbicide to stick to the weed leaves. Even then, most of the herbicide ends up bouncing off the weed leaves.
If you are lucky enough to get the correct moisture for the herbicide to stick to the weeds leaves, you have to wish for some additional luck that you don’t get any rain for at least 24 hours. Otherwise the herbicide will wash off the leaves and this will all be for nothing.
Also, broadcasting a post-emergent herbicide over your entire lawn is a waste. Chances are there are just some specific areas that require herbicide so I recommend spot treating those problem areas instead of putting expensive chemicals over your entire lawn.
Spot Treat Lawn Using Liquid Herbicide
Spot treating your lawn means going around your lawn with a liquid herbicide and spraying just the weeds. There are a lot of products that are safe to use on your lawn. A lot of these products even come with an applicator. The best products to use depend on whether you have cool season grass or warm season grass:
For Cool Season Grass:
I really like Ortho Weed B Gone Plus Crabgrass Control for spot treating lawn weeds. If you have a lot of weeds consider buying the concentrate here to save some money: Ortho Weed B Gone Concentrate. The concentrate is meant to be mixed in a tank sprayer.
For tank sprayers you can either get a small 1-2 gallon tank or a larger 4 gallon tank. The 1-2 gallon tank is usually fine for spot treating: 1 Gallon Tank Sprayer
To treat your lawn, I recommend walking your lawn frequently (every week) and spraying any lawn weeds you see. This will help you stay on top of weeds and will prevent them from spreading. Many broadleaf weeds require a follow up treatment.
Also, it is highly recommend you mix a little Surfactant in with the Ortho Weed B gone, or any other liquid post emergent herbicide. The Surfactant helps the herbicide stick to the leaf of the plants. When broadleaf weeds are established they can get a waxy coating on their leaves that makes the herbicide hard to stick to. If you’ve ever been unsuccessful with liquid post emergent herbicides it’s likely this was the problem. Mixing in a little Surfactant can make a big difference. You can purchase Surfactant here: Surfactant
Another great post emergent liquid herbicide is Tenacity. The active ingredient in Tenacity is Mesotrione. Mesotrione kills a lot of tough grassy weeds that other herbicides don’t. Some of these include Creeping Bentgrass, Nimblewill, and Poa Annua. These weeds can be a nuisance in cool season lawns and Tenacity is the best selective herbicide to kill them.
Another bonus of Tenacity is if you’re planning on seeding areas of your lawn or planning on a lawn renovation this is a safe product to use. Many other liquid herbicides recommend pausing applications at least a month before seeding. With Tenacity you can apply leading up to your renovation. Usually you can even treat weeds at the same time as seeding (exception with fine fescue, and some other grass types, always read label).
Tenacity does have a couple of drawbacks. For starters it takes awhile to see results. It could take up to 2-3 weeks before weeds die back. Also, because it works by blocking photosynthesis in weeds, you’ll see the weeds turn a bleached white color. This will make weeds stand out as they are dying back. Lastly, you might see some temporary bleaching of your grass. This is usually temporary and grass will eventually green back up.
Just like with spot treating, mixing Surfactant into your liquid herbicide will make blank spraying more effective.
For Warm Season Grass:
For warm season grass, my favorite all around post emergent liquid herbicide is Image Southern Weed Killer. The label says for use on St. Augustine and Centipede grass but it can also be used on other warm season grasses such as Zoysia and Bermuda. This product is a concentrate and should be mixed with water in a concentrate. It will kill a lot of common weeds such as Dandelion, Clover, Chickweed, Dollarweed and many others.
The one downside to the Image Southern Lawn Weed Killer is it’s not the best choice for killing some of the tougher weeds such as Crabgrass, Doveweed, Dallisgrass, and others. If you have these weeds then I’d suggest using Celsius WG. You might have some sticker shock when you see the price of this product but keep in mind it is a concentrate that gets mixed with water so you get a lot of mileage out of it. Chances are this product will last you several seasons.
To treat your lawn with either of these products, I recommend walking your lawn frequently (every week) and spraying any lawn weeds you see. This will help you stay on top of weeds and will prevent them from spreading. Many broadleaf weeds require a follow up treatment. Both products benefit from adding a little Surfactant.
Blanket Spray If There’s a Lot of Weeds
What if you have so many weeds that spot treating isn’t an option?
If you have a lot of weeds mixed in with your lawn it might seem ridiculous to go around and spray each individual weed.
Instead, you’re better off blanket spraying your entire lawn with your lawn safe liquid herbicide. Blanket spraying usually requires a larger 4 gallon tank sprayer with a handle for pumping: 4 Gallon Tank Sprayer
You simply mix the liquid herbicide with water (according to the blanket application instructions on the label) and walk your entire lawn while spraying. I like to go up and down in rows, usually following my mowing lines.
Prevention with Pre-Emergent Herbicides
Unlike granular post-emergent herbicides, granular pre-emergent herbicides can work very well in preventing lawn weeds from becoming established. I strongly recommend using pre-emergent herbicides at 3 specific times during the year. Check out my custom lawn care program to see what pre-emergent to apply and when.
Pre-emergent herbicides prevent crabgrass, as well as other broadleaf weeds from germinating. Prevention is definitely the best method for dealing with broadleaf weeds.
Are There Any Chemical Free Ways to Kill Weeds in Lawn?
There’s always the manual way, which is actually the most effective way. There is a great weed grabbing tool that many people use to pull weeds completely out of their lawn, including the weeds root system.
It is especially effective for removing dandelions since dandelions have a long tap root that can be hard to rip out.
Renovate Lawn to Combat Weeds
If your lawn is overwhelmed with weeds you might be convinced you have to rip everything out and start over. Before doing so, consider core aerating and overseeding. Core aerating and overseeding, can drastically improve your lawn.
If you want to go a step further, top dressing your lawn, in addition to core aerating and overseeding is the ultimate lawn renovation.
As usual the best recommendation I can give for combating lawn weeds is sticking to a good lawn care program and maintaining a healthy lawn.
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