Acetic Acid (Vinegar) as an Herbicide

Many of us have heard about the benefits of using vinegar in gardens, mainly as an herbicide. But how effective is vinegar and what else can it be used for? Let’s find out more about how to use vinegar in the garden. 

Using Vinegar in Gardens It has been said that one of the benefits of vinegar in the garden is as a fertilizing agent. Nope. Acetic acid only contains carbon hydrogen and oxygen — stuff the plant can get from the air. Vinegar has been recommended for use to up the pH levels in your soil. Apparently not so. The affects are temporary and require large amounts of vinegar in the garden before anything noteworthy occurs. 

The last, but most commonly suggested use for vinegar in the garden is as an herbicide. Household white vinegar, at its 5 percent acetic acid level, does indeed burn the tops of the weed. It does not, however, have any effect on the roots of the weed and will toast the foliage of any other plants it comes in contact with. Vinegar as Herbicide Woo hoo! Vinegar as herbicide: a safe, easily found (often in the kitchen cabinet) and inexpensive product to use in the control of weeds. 

Tell me all about it! Okay, I will. The use of vinegar in the garden to retard weed growth has long been recommended by your neighbor, your neighbor’s grandmother and your own mother, but does it work?

Read more at Gardening Know How: Garden Uses For Vinegar – Tips For Using Vinegar In Gardens https://www.gardeningknowhow.com/garden-how-to/info/use-vinegar-in-gardens.htm

Vinegar contains acetic acid (about 5 percent), which as the nomenclature suggests, burns upon contact. Actually, for any of you who have inhaled a whiff of vinegar, it also affects the mucus membranes and causes a swift reaction. Due to its burning effects, using vinegar in the garden has been touted as a cure all for a number of garden afflictions, most notably weed control. 

The acetic acid of vinegar dissolves the cell membranes resulting in desiccation of tissues and death of the plant. While this sounds like a splendid outcome for the plague of weeds invading your yard, I suspect you wouldn’t be quite as thrilled if vinegar as herbicide were to damage your perennials or garden veggies. A higher acetic acid (20 percent) product can be purchased, but this has the same potentially damaging results as utilizing vinegar as herbicide. At these higher concentrations of acetic acid, some weed control has been shown to be established (80 to 100 percent of smaller weeds), but be sure to follow the manufacturer’s instructions. Also, be aware of its caustic effects on your nasal passages, eyes and skin, not to mention garden plants and take the appropriate precautions. 

Despite the longstanding proponents for using vinegar in gardens, little beneficial information has been proven. It seems that research conducted by the USDA with solutions containing 5 percent vinegar has not been shown to be a reliable weed control. Higher concentrations of this acid (10 to 20 percent) found in retail products may retard the growth of some annual weeds and will indeed kill the foliage of perennial weeds such as Canada thistle, but without killing the roots; thereby, resulting in regeneration. 

In summary, vinegar used as herbicide may be slightly effective on small annual weeds during the lawn’s dormancy and prior to garden planting, but as a long-term weed control, it’s probably better to stick with the old standby — hand pulling or digging. Additional Garden Uses for Vinegar Don’t be alarmed if the benefits of vinegar aren’t what you thought they would be. 

There are other garden uses for vinegar that can be just as good, if not better. Using vinegar in gardens goes far beyond weed control. Here are more options for how to use vinegar in the garden: Freshen up cut flowers. Add 2 tablespoons vinegar and 1 teaspoon sugar for each quart of water. Deter ants by spraying vinegar around door and window frames, and along other known ant trails. Eliminate calcium buildup on brick or on limestone with half vinegar and half water. Spray on and then just let it set. 

Clean rust from garden tools and spigots by soaking in undiluted vinegar overnight. And finally, don’t forget the animals. For instance, you can remove skunk odor from a dog by rubbing down the fur with full strength vinegar and then rinse clean. Keep cats away from garden or play areas (especially sandboxes). Just sprinkle vinegar in these areas. Cats hate the smell.

Read more at Gardening Know How: Garden Uses For Vinegar – Tips For Using Vinegar In Gardens https://www.gardeningknowhow.com/garden-how-to/info/use-vinegar-in-gardens.htm

How it works as a pesticide Acetic acid is applied as a liquid spray or drench to weeds after they emerge from the soil. It is a contact herbicide, meaning it only affects plant tissue it touches. The acid breaks up cell membranes and makes them leak, causing the plant to dry out and die. Depending on plant age, air temperature, humidity, and direct sunlight levels, this may take from a few hours to several days. The drying effect is not limited to just certain plants; any new plant tissue can be affected. 

Avoid getting drops of spray onto plants you do not want damaged. 

Young seedlings and new growth have a thinner leaf cuticle than older plants or woody parts, making it easier for acetic acid to break down cell membranes. For example, in one study acetic acid sprayed at 5%–20% concentration killed 80%–100% of weed seedlings that were from 3 inches–9 inches tall. However, when 10% acetic acid was sprayed on mature blackberry plants, only 5% of leaves were burned back. 

Thick, waxy cuticles and woody plant tissue are more resistant to liquid entering, thus harder to kill. To overcome this, trim perennial weeds so they regrow tender new growth. Follow this with a spray application to the new growth to deplete the weed’s energy stores. Many cycles of trim-and-spray are likely needed to effectively treat stubborn perennial weeds such as Canada thistle (Figure 1). Acetic acid is sometimes mixed with citric or other acids. It can also be listed as an inert ingredient on some herbicide labels. 

The point to remember with acetic acid is that high concentrations are more effective on woody perennial weeds, while low concentrations will work effectively only on very young weed seedlings.

Some of the articles, research papers that may interest you:

https://ecommons.cornell.edu/handle/1813/46234  

Evaluation of acetic acid based herbicides for use in broad-spectrum turfgrass and weed control

https://www.cambridge.org/core/journals/weed-technology/article/abs/integration-of-vinegar-for-inrow-weed-control-in-transplanted-bell-pepper-and-broccoli/43068DA3775AC0CB4B1287C043B82DFD

Integration of Vinegar for In-Row Weed Control in Transplanted Bell Pepper and Broccoli

Herbicidal Effects of Vinegar and a Clove Oil Product on Redroot Pigweed (Amaranthus retroflexus) and Velvetleaf (Abutilon theophrasti) 

https://www.researchgate.net/publication/232684399_Herbicidal_Effects_of_Vinegar_and_a_Clove_Oil_Product_on_Redroot_Pigweed_Amaranthus_retroflexus_and_Velvetleaf_Abutilon_theophrasti

What's the benefits of wood vinegar for different crops?https://www.researchgate.net/post/Whats_the_benefits_of_wood_vinegar_for_different_crops

Read more at: https://newcropsorganics.ces.ncsu.edu/2013/08/acetic-acid-vinegar-as-an-herbicide/