Weed Killer Guide may collect a share of sales or other compensation from the links on this page.
If you have a lawn that is full of weeds, your quest for a nice-looking lawn might seem hopeless without using the nuclear option of burn, remove, replant. Never despair, there are several other options to consider first that are much less drastic.
Here, we will review 4 basic methods of weed control for your lawn. Some methods take a while and require patience, but the results are dependable and consistent.
They are the ever-popular prevention (don’t let any weeds get in!), spot treatments with an herbicide (use with caution), lawn-wide weed killer treatment (involves a mix of things), and finally good old-fashioned hand cultivation (doing it the hard way).
Table of Contents
Employing preventative strategies to keep weeds out of the lawn is key to long-term success. Essentially, an established lawn with a dense turf mat will naturally keep weeds out.
This also entails your lawn grass root system dominating the soil mass so that weeds do not have a place to set up. Training your grass to develop deep root systems is easy.
This involves watering the correct amounts. Not too much, or roots will grow shallowly.
And cutting to the appropriate height. There is a direct positive correlation between grass height and root depth.
Mowing heights for cool climate grasses are as follows:
- Fescue (red creeping and chewing): 1.5-2.5 inches
- Tall fescue, bluegrass, perennial ryegrass: 1.5-3.0 inches
- Bent grass: 0.25-0.75 inches
Mowing heights for warm climate grasses are as follows:
- St. Augustine: 1.0-3.0 inches
- Centipede, carpetgrass: 1.0-2.0 inches
- Bermuda, Zoysia: 0.5-1.0 inches
However, prevention only works in advance or after a major de-weeding for purposes of maintenance.
Weed killer spot treatment
Small patches of troublesome weeds can be spot treated to eliminate them without too much negative impact on neighboring turf grass. Chemicals must be applied as directed and always remember: less is more.
Identifying the weed in question is also of importance in that amount and frequency of application will vary. Ensure that a weed is a weed first before treatment, which are:
Broadleaf (e.g., dandelion, clover, ground ivy/creeping Charlie, oxalis, chickweed, dollarweed, henbit, plantain, thistle).
Grass-like weed (e.g., nutsedge, wild onion, wild garlic)
Grassy weed (e.g., crab grass, foxtail, annual bluegrass, quackgrass).
The chemicals can be directly and discretely applied to the weed in question on an as-needed basis. Using sparing amounts of chemical reduces the impact on nearby turf.
Many products are selective (for example, broadleaf weeds) and are formulated to reduce dispersion from the application site.
Effective products for spot treatment are made by Spectracide and Scotts.
Comparison Table – Weed Killer
|1. Scotts Turf Builder Triple Action||CHECK PRICE|
|2. Scotts Turf Builder Southern Triple Action||CHECK PRICE|
|3. Scotts Weed Control for Lawns||CHECK PRICE|
|4. Spectracide Weed Stop for Lawns Plus Crabgrass Killer||CHECK PRICE|
Weed killer broad treatment
Sometimes, you are faced with wide-scale invasion. In this instance, there are products which can be broadly applied to the entire lawn. Which one you use will depend on whether it is time to fertilize the lawn or not, as the chemicals involved are combination products.
How does it work? Scotts Turf Builder Triple Action uses a mixture of three herbicides (pendimethalin, 2,4-D, and MCPP-p) and fertilizer (NPK 16-0-1).
Pendimethalin is used in both preemergence and postemergence treatments for annual grasses and some broadleaf weeds. 2,4-D will kill most broadleaf weeds and will not affect grasses. MCPP-p or mecoprop generally targets the broadleaf weeds missed by 2,4-D.
Scotts Turf Builder Triple Action should only be applied at certain times of the year as directed. In spring, it is effective on problem grasses (crabgrass, barnyard grass, fall panicum, foxtail) and broadleaf grasses (corn speedwell, knotweed, chickweed, oxalis).
In summer, it is effective against broadleaf weeds such as prostrate spurge, purslane, and oxalis. In the fall, use it on grasses such as annual bluegrass, and broadleaves such as chickweed and henbit. There are also a broad variety of other broadleaf weeds against which it is effective.
You should not use this product on St. Augustine, bentgrass, carpetgrass, dichondra, floratam, or lippia.
What’s the Southern addition in the formulation? Scotts Turf Builder Southern Triple Action is formulated to work with warm climate turf grasses and weeds associated with those regions. It consists of a mixture of an herbicide (atrazine) an insecticide (bifenthrin), and fertilizer (NPK 29-0-10).
Atrazine is used in both preemergence and postemergence treatments for broadleaf and grassy weeds. Bifenthrin is a pyrethroid insecticide used commonly against imported fire ants (Solenopsis invicta), and it is also effective against a variety of turf pests such as armyworms, cutworms, grasshoppers, mole crickets, and sod webworms.
It is effective against a large number of southern broadleaf weeds. You should not use this product on bahiagrass, bermudagrass, bluegrass, dichondra, bentgrass, fine or tall fescue, or ryegrass.
How is this different from the other two Scotts products? Scotts Weed Control for Lawns consists of three herbicides (2,4-D, dicamba, and MCPP-p) and a negligible amount of fertilizer (NPK 0-0-1).
Dicamba is a postemergence herbicide directed towards annual and perennial broadleaf weeds (2,4-D and MCPP-p are discussed above). This mix is intended for use in de-weeding lawns when you do not need to fertilize, or wish to use a different fertilizer rate than the rates included in the mixes above.
Kills over 200 types of weeds; see the product literature for details. You should not use this product on St. Augustine grass, dichondra, carpetgrass, or bentgrass.
Spectracide Weed Stop for Lawns Plus Crabgrass Killer contains herbicides (2,4-D, quinclorac, dicamba, sulfentrazone).
Quinclorac is a plant hormone mimic that is used for crabgrass control. Sulfentrazone is a postemergence herbicide directed at broadleaf weeds (nutsedge, clover, spurge, curly dock, etc.)
2,4-D and dicamba are discussed above. Spectracide Weed Stop controls over 470 different types of broadleaf and annual weeds (including crabgrass, as per the title).
The product is intended for use on cool climate grasses (Kentucky bluegrass, fescues, and perennial ryegrass) and warm climate grasses (Bermudagrass, buffalograss, and zoysia).
Hand application and cultivation
When all else fails, there is the laborious process of painting herbicide on selected weeds and pulling them by hand. However, there is a way to do this and a way not to do this.
Use a non-selective herbicide like glyphosate (RoundUp). This will treat the weed, spreading herbicide through the weed to the roots. Why? Let’s face it, you are not going to get all the roots.