Aggressive and opportunistic, weeds are evolved to cover large bare patches of soil with alacrity. And battling one of nature’s hardiest plant types over large tracts of land can get expensive.
But don’t let weeds get your down. We’ve collaborated with lawn care professionals and turfgrass professors in order to determine what is important in a weed killer, and to select the best weed killers suited for large areas.
Factors we considered include the following: effectiveness, toxicity, price per fluid ounce, manufacturer reputation, and environmental friendliness. We hope this helps you choose the right option for you!
Here are the best weed killers for large areas, according to turfgrass experts:
1. Southern Ag Amine 2,4-D WEED KILLER, White Bottle
Folks looking to rid their lovely lawn of pesky broadleaf should look no further than Southern Ag’s weed killer.
It starts eliminating a wide range of weeds within hours, with full desiccation in as little as 3 days. And with a usage of 1 to 4 pints per acre it’s one of the cheapest and most effective weed killers available.
This 2, 4-D based formula is safe to use on some of the more delicate Southern lawns as well, including St Augustine & Bermuda grass.
However, please note that it is not safe for use around crops or pets.
Specifications:
- Selective weed killer
- Active ingredient: 2, 4-D
- Rain proof in 24 hours
- Treats up to 32,000 square feet per bottle
Pros:
- Highly effective
- Will not harm most lawns
- Huge area, low cost
Cons:
- Concentrate, must be mixed
- Highly toxic
2. Spectracide Weed & Feed 20-0-0, Ready-to-Spray, 32-Ounce
Spectracide is one of the most potent of the ready to use weed killers. It covers a decent amount of ground for the price and has a handy spray nozzle that just needs a garden hose to get your started.
Not only that, but the double action weed & feed formula will fertilize your lawn to help it naturally fight off future weeds.
It isn’t appropriate for truly massive areas due to the cost but should suffice for large lawns.
Specifications:
- Selective weed killer and lawn fertilizer
- Active ingredients: 2, 4-D, MCPP, dichlorprop-p
- Rain proof in 24 hours
- Treats up to 7,500 square feet per bottle
Pros:
- Kills weeds and supports lawn health
- Ready to use
- Medium-large lawn size
Cons:
- Does not prevent weeds
- Highly toxic
3. RM43 43-Percent Glyphosate Plus Weed Preventer Total Vegetation Control, 1-Gallon
Need an all-purpose vegetation killer that will last? RM43’s incredibly effective formula will clear plants from close to half an acre with 1 bottle. And keep it clear for the next year!
We don’t recommend this for use next to galvanized steel fences, as many farmers have found it to corrode the coating from the wire. It is also toxic and not for use near crops or pets.
Specifications:
- Non-selective vegetation killer and preventer
- Active ingredients: glyphosate
- Rain proof in 2 hours
- Treats 17,297 square feet
Pros:
- Highly effective
- Long lasting
- Large area for the money
Cons:
- Kills everything it touches
- Concentrate, must be mixed
- Highly toxic
4. BASF Drive XLR8 Crabgrass Herbicide (1/2 Gallon, 64 OZ.)
Crab grass got ya down? BASF offers a super cost per square foot solution.
BASF is death for crab grass and grassy weeds but also deals with other common pests including dandelion, clover, and dollar weed. And just half a gallon will cover an entire acre.
Quinclorac has been known to yellow Bermuda grass though and is not for use on drought stressed lawns or during temperatures above 90 degrees.
Specifications:
- Selective weed killer
- Active ingredient: quinclorac
- Rainproof in 1 hour
- Treats up to 43,500 square feet
Pros:
- Super effective vs grassy weeds
- Enormous area, low cost
Cons:
- Concentrate, must mix
- Not safe for all lawns
5. Doctor Kirchner Natural Weed & Grass Killer (1 Gallon) No Hormone Disrupting Chemicals
Gardeners, pet owners, and parents alike will appreciate the totally non-toxic vegetation killer from Doctor Kirchner.
This potent vegetation killer can be used near crops and is immediately safe for dogs and children who love to romp around the yard.
And don’t worry about hormone disrupting chemicals and rain clouds. With sustainable ingredient sourcing and a sea water based formula, Doctor Kirchner’s is good for the planet too.
It gets rather expensive when used over bigger lawns, but peace of mind is priceless.
Specifications:
- Non-selective vegetation killer
- Active ingredient: salt
- Other ingredients: water, vinegar, soap
Pros:
- Non-toxic, extremely safe
- Sustainably sourced ingredients
- Ready to use
Cons:
- Kills everything it touches
- Expensive over large areas
Buyers Guide
Selective vs Non-selective Weed Killer
One of the first considerations for choosing an effective weed killer for a large area is to decide whether you want to kill all vegetation, or just the weeds.
Selective weed killers are specially formulated to leave grass and turf relatively unscathed but kill and/or prevent commons weeds.
Folks looking to de-weed a lawn will likely want to choose a selective weed killer. That way you can have your plush greenspace and get rid of unsightly, allergen causing weeds.
Common active ingredients in selective weed killers:
- 2, 4-D
- Mecoprop (MCPP)
- Dicamba
Non-selective types are more of a scorched Earth policy. This type will kill any vegetation it comes into contact with, and sometimes even nearby plants.
These weed killers are best reserved for projects like driveways, around buildings, and far from crops or livestock.
Common active ingredients in non-selective weed killers:
- Paraquat
- Glyphosate
- Glufosinate
- Vinegar
Weed Killer Longevity
How long do you need your weed killer to be effective for? Some formulas are dual action killers and preventers, making the environment inhospitable to weed germination for up to a year.
Those hoping to clear weeds and then plant desirable species in their place should steer clear of long-term weed killers. Any long-lasting weed killer could easily kill or retard the growth of new plants just as well as the weeds you hate.
Ways to Kill Weeds Without Using Weed Killer
Vinegar
There are even some pre-mixed products that use vinegar available for weed and grass killing. The most popular and effective is the Green Gobbler brand. See how it works in Stoney Ridge Farmer’s video.
If you want the most economical approach to using vinegar, however, we recommend purchasing the concentrated vinegar yourself and mixing to desired strength.
Use caution when handling high acidity vinegar though, as it can be extremely corrosive.
Make your own recipe
Many gardeners swear by the budget friendly approach of making your own weed killer. Most recipes are some combination of soap, salt, vinegar, and water.
Take some time choosing the right types of ingredients, or it may not work as you hoped. In his video, Tony Piela shows how he chooses and measures out his own mixture and shows the results.
We appreciate the non-toxic approach as well as the customizable nature. When working with low-to-no toxicity ingredients like these you can take a trial-and-error approach to find the right strength for your weed situation.
Kill them with fire
Want to bring a little fun to weed killing? Try blasting those pesky dandelions with fire! Check out the Red Dragon weed torches, a quality and highly effective brand.
It is not the most time and cost-effective method for weed killing over larger areas, but it is completely non-toxic.
Please use caution when using fire. Wear protective gear and keep an eye on drought conditions and underbrush, or you may risk starting the bigger fire than intended.
Frequently Asked Questions
What time of year should you apply weed killer?
That depends entirely upon which weeds you are trying to kill.
Clemson’s College of Agriculture, Forestry, and Life Sciences’ comprehensive weed control guide tells you all about which weeds need to be taken care of when.
For Southern states, check out Clemson’s guide to managing weed in warm season lawns.
How often can you apply weed killer?
Your weed killer’s label will tell you how often you can apply the product safely. Avoid oversaturating the area, as well as applying more often than recommended.
Always follow the directions of your weed killer as close to the letter as possible. Diverging from the manufacturer’s directives can result in disastrous effects to local wildlife, plant life, and soil nutrients.
How do I identify which weeds I need to focus on?
Clemson University has a highly informative guide on weed identification as well. Get to know your adversary so that you can better understand how to effectively deal with them.
Conclusion
The clear winner of bang for buck is Southern Ag’s selective weed killer. One, quart sized bottle will cost you less than $20 and wipe out weeds for nearly an entire acre while leaving grass fluffy and green.
Or, for folks who want all plant matter gone for a year or more check out RM43’s glyphosate-based concentrate. It may cover less ground, but you won’t have to reapply for a long time!
Happy weeding!
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