The passionate cultivars Jim and c say that, in their garden and planting rows, weeds have never been much of a problem. By utilizing heavy amounts of mulch, by applying protective covering of crops in the off-season, and especially by having a simple 5-10 minute-a-day approach to weed maintenance during the growing season, they have succeed to harvest a ‘paradise crop’ year after year.
Yet, when it comes to maintaining and trimming of the stone walkways, driveways, paths, and brick patios around their estate, they say that a thick coat of mulch and planting of cover crops does not quite give them the look they are aiming for. Have you experienced the same problem?
For them, the way out to keep these front-most areas weed-free has been a simple natural weed killer solution using vinegar as the main active ingredient. It has not only proven to be effective, but it has also shown to be so much safer, having to use a single drop of a commercial herbicide like Roundup. Let alone- now they do not have to worry about harsh toxic chemicals, which have been killing their honey bees, as well as other beneficial insects when used.
Though you can use the standard off-the-shelf vinegar, they prefer to use a stronger solution labeled as the horticultural vinegar, which has a much higher acidity content (20%) than the typical 5% found in the regular store-bought items.
To meet your various needs, we give you the recipes for both of them a few paragraphs below.
Horticultural vinegar extract
Please take into account that both regular and horticultural vinegar weed-eradicator solutions are non-specific — they will kill whatever they come across! So this is not a safe solution for using on your delicate lawn or in close-knit planting solutions. It is, however, excellent for taking care of weeds in sidewalk cracks, brick walkways, or gravel-covered areas. In addition, when using the higher-strength vinegar, you must take precautions to prevent burns to your skin and eyes (goggles, gloves, long sleeves will do the job) in case of accidental contact. Remember that the vinegar is a natural acid – that is why it is so efficient in killing weeds.
When and how to spray the vinegar:
No matter which mixture you use, you should only spray when the sun is gone, and there is no forecast of upcoming rain. The hotter the temperature is, the better! With the strong solution, in most cases you will see the leaves start to curl up and brown within only 4-6 hours. If you use, the regular vinegar solution, it can take up to 12-24 hours to see the first results, depending on the weather conditions.
For the arduous Jim and Marylyn, heavy mulching and cover crops are still the answer for weed control in their nicely-trimmed garden. This mixture really accelerates its effectiveness in the hot sun. They use a standard garden sprayer to apply the solution to all of the weed leaves. It makes quick work of maintaining the property, and keeping the paths and driveway free of all those come-back-again weeds.
One last note: You may need to re-apply every few weeks through the summer for maximum effectiveness.
About the 2 recipes below:
Although there are hundreds of recipes that can be found online, we have found the following two solutions to be the most effective in controlling weeds in driveways and pathways alike.
Also, there are a lot of ‘mixed feelings’ about using the solution in the garden, because it may, or it may not, increase the soil’s acidity over the course of time. But when garden and flower-beds are in question, it simply cannot be pointed out enough that the more your ground is covered, the fewer weeds you will ever have to encounter. There is no need for it, right?
The Traditional Vinegar Recipe
- 1 gallon of store-bought vinegar
- ¼ cup of salt (Morton’s, etc.)
- 1 teaspoon of dish soap (you can use an organic soap if you like – it helps the solution adhere longer to the weed’s leaves)
Mix all the ingredients listed above, and use the vinegar within 7 days for maximum effectiveness.
The Horticultural Vinegar Recipe
- 1 quart of horticultural vinegar (20% acidity)
- 1 gallon of hot water
- 1 teaspoon of dish soap (you can use an organic soap if you like – it just helps the solution adhere to the weed’s leaves.
- ¼ cup of salt
- 1 oz. of gin
Mix all the ingredients listed in the recipe, and again use it within 7 days for maximum impact.
Where to find it: You can find the horticultural solution of vinegar online, or at some local feed and garden stores. However, make sure when purchasing that the solution is at a 20% acidic level.
Take notice: It is important to note that a 20% horticultural solution of vinegar is a pretty harsh natural acid. It should be handled with great care, so you must wear gloves and goggles when preparing it.
Fact Sheet for Vinegar/Acetic Acid Recommendations: PIC-01002
Authors: Catherine H. Daniels (from the Washington State University) and Janet Fults (from the Oregon Department of Agriculture); Printed: 19 September 2002
In May 2002, USDA-ARS issued a press release describing their research on weed control using vinegar. The research was prompted by the organic farming community’s need for an inexpensive and environmentally benign weed killer. Greenhouse and field studies indicated that while 5% vinegar solutions did not produce reliable weed control, solutions of 10, 15, and 20% provided 80-100% control of certain annual weeds (foxtail, lambsquarters, pigweed, and
velvetleaf). Perennial weeds (Canada thistle) treated with 5% vinegar showed 100% shoot burndown but roots were not affected, therefore shoots always re-grew. Study details can be found at their Web site, http://www.barc.usda.gov/anri/sasl/vinegar.html The ARS release noted the potential use of vinegar as an ideal sidewalk crack and crevice treatment.
Homeowners had already heard about purported vinegar uses for killing blackberries in a June 2001 Seattle Post Intelligencer article and had deluged Extension offices and Master Gardener’s for more information.
What is actually registered for use?
Five products containing acetic acid and marketed as herbicides are currently registered for use in Washington. Two of them are 25% concentrates with instructions to dilute down to 6.25% and use on rights-of-ways, non-crop, and industrial lands. Three of them are labeled for homeowner use (St. Gabriel Labs Fast Acting Burn Out RTU, Nature’s Glory Weed and Grass Killer RTU,
and Greenergy’s Blackberry and Brush Block). Their acetic acid concentrations are 6.25%, 6.25%, and 7% respectively. Curiously, Greenergy’s product label lists acetic acid as an inert ingredient; citric acid is listed as the active ingredient. By listing the ingredients this way, Greenergy is able to take advantage of EPA’s “Minimum Risk Pesticide” definition. Products falling under this category are also known as “25(b) products” after the FIFRA rule describing criteria for minimum risk pesticides. Such products need not be registered at the Federal level and do not carry an EPA registration number. Washington law requires 25(b) products to go
through the Washington State Department of Agriculture’s (WSDA) registration process regardless, while the Oregon Department of Agriculture (ODA) does not require state registration of 25(b) products. Fast Acting Burn Out RTU (EPA Reg # 69836-2-63191) is not registered in Oregon, leaving two products, Nature’s Glory Weed and Grass Killer RTU (EPA Reg #69836-2), and Greenergy’s Blackberry and Brush Block (25(b) product so no EPA number) as legal to use in Oregon.
What actually works?
Preliminary field tests in Washington State using 7% vinegar solutions showed results similar to the ARS study at 5%, namely lack of reliable weed control. Extension personnel in Washington are able to legally recommend any of the three homeowner-registered products listed above,although data demonstrates erratic weed control. In other words, people should be told it might not work in their situation.
Aspects to take into account with higher concentrations of acetic acid
A few weeks ago a product called Bradfield Horticultural Vinegar (20% acetic acid) was found in a local home and garden center. At first glance it seemed the answer consumers had been clamoring for. However, the product is not registered with EPA and does not qualify under the Minimum Risk Pesticide category for non-registration. The company has found a gray area of the legal system. There is a part of federal law which states that if a product clearly has uses other than as a pesticide AND the company makes no claims about that product having
pesticidal uses, it does not have to be registered as a pesticide. This law makes sense for things like citric acid, culinary herbs and their oils, and other products that are used in many other applications besides pesticides. Acetic acid has numerous other uses so it, too, falls under this category.
Bradfield Industries has changed their product label; the current version does not
make any pesticide claims and thus, does not have to be registered as a pesticide. Another party has attached (with a twist-tie) an information sheet discussing some of the common uses for acetic acid: cleaning farm equipment, lowering pH in
fertigation and other foliar sprays, and as a herbicide. Further investigation should be conducted to determine who is attaching these “pesticidal claims” to the product as the responsible party has transformed a legal product into a product in violation of state and federal law. In the meantime, this is a legal fine point that affects
Extension personnel directly. If the material claims to kill pests (weeds) it becomes a pesticide. Making either verbal or written pesticidal claims for a specific product that is not registered by EPA, or legally exempt from EPA registration, may be considered a violation of federal law.
University Extension cannot be in a position of making recommendations or pesticidal claims for any unregistered pesticide.
Why are we making such a big deal over these picky details?
For 2 very good reasons: legality and safety.
Legally, extension is culpable (personally as well as through the University) in recommending unregistered pesticides (even 25(b) products for those of us in Washington State since they need WSDA registration).
We also have practical safety concerns. Acetic acid concentrations over 11% can cause burns upon skin contact. Eye contact can result in severe burns and permanent corneal injury. The other concentrated acetic acid products registered through EPA and the states for commercial use all have restricted entry intervals of 48 hours and list personal protection equipment to be used by the applicator. None of this safety information is included on the twist-tie information on the jug of Bradfield Horticultural Vinegar.
Because the public is used to thinking of vinegar as something you can safely splash on your salad and eat (household vinegar is typically 5% acetic acid), they are generally unaware of potential dangers of a higher concentration.
Bottom line: At this time, the only acetic acid-containing products Extension personnel can currently recommend to homeowners for weed control are the ones mentioned in the product registration discussion above.
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