How long vinegar actually keeps weeds away—plus, tips for making it last longer

This natural herbicide needs to be reapplied for long-term success.

When it comes to reducing pesky weeds, one household ingredient provides a natural, fast-acting solution: vinegar. Widely used in the gardening world as a natural herbicide, vinegar contains acetic acid, which strips away the plant’s protective, waxy cuticle and ruptures cell membranes, causing rapid dehydration, tissue breakdown, and ultimately, plant death.

However, while vinegar may be effective in the short term, its effects are not long-lasting and require reapplication to maintain its weed-fighting power. Below, gardening experts explain how long vinegar keeps weeds at bay, how often it should be reapplied, and common mistakes to avoid when using vinegar as a natural herbicide.

Meet Our Expert

• Ankit K. Singh, assistant professor and ornamental horticulture educator at the University of Maine Extension
• Emily Scott, master gardener and owner of Scott Farm in Maine.

Related: This 3-Ingredient Homemade Weed Killer Uses Vinegar to Safely Remove Unwanted Plants

How Long Does Vinegar Keep Weeds Away?

Vinegar works as an herbicide by burning or drying out the leaves it contacts, but it typically doesn’t penetrate the roots. As a result, the plant may regrow, especially if it is a larger or perennial weed, explains Ankit K. Singh, assistant professor and ornamental horticulture educator at the University of Maine Extension.

For small, young annual weeds, vinegar may cause visible damage within a day or two, and some may die. For larger weeds or weeds with deeper roots, the top growth may brown and look dead, but the plant can come back. “In many cases, the effect lasts only a few days to a couple of weeks unless the weeds are very young or vinegar is applied more than once,” he says.

How to Make Vinegar Last Longer As a Weed Killer

Although vinegar’s effectiveness as a weed killer is short-lived, there are ways to make it last longer.

• Apply on a warm day: Treat weeds with vinegar on a warm, sunny, dry day, when rain is not expected, as water can wash away the vinegar, reducing its efficacy.
• Spray the weed thoroughly: The entire plant needs to be sprayed well, as vinegar only affects the plant tissue it touches, Singh says.
• Reapply the spray: Repeated applications are often needed, especially for perennial weeds, to keep them from growing back. Aim to reapply every couple of days.
• Use a surfactant: Adding a small amount of soap to your vinegar mixture can help it better adhere to the leaves, particularly on waxy weeds, Singh says.
• Use it with other natural treatments: Vinegar works best as part of a bigger approach. “Pulling larger weeds, hoeing young weeds, adding mulch, or using landscape fabric in pathways will usually give better long-term results,” Singh says.

Mistakes to Avoid

Although vinegar can help keep small weeds at bay, there are common mistakes to avoid to safeguard nearby plants and ensure a successful application.

Spraying Nearby Plants

Spray the vinegar solution carefully and directly onto the targeted weeds. Careless spraying can harm nearby plants, including valuable flowers and even your lawn. “Vinegar isn’t selective and will kill everything around it,” says Emily Scott, master gardener and owner of Scott Farm in Maine.

To protect your plants, switch your sprayer nozzle to a direct stream rather than a fine mist, and avoid spraying on windy days. Additionally, you can hold a piece of cardboard as a shield between the weeds and desirable plants.

Applying on a Cold, Cloudy, or Wet Day

Acetic acid, the primary component of vinegar, requires high temperatures to effectively dehydrate plant cells. If it is applied just before a rainstorm, the solution will be washed away before it has a chance to take effect.

Using the Wrong Vinegar Strength

Household vinegar typically contains about 5 percent acetic acid, which can be useful for controlling small weeds, but its effectiveness is limited. In contrast, stronger horticultural vinegar products are more potent and can tackle tougher weeds.

Scott recommends using a horticultural vinegar solution with a concentration of 20 percent or more for optimal effectiveness. This stronger solution contains a higher level of acetic acid, which allows it to draw moisture from the plant’s tissues more quickly than the standard 5 percent household vinegar. Using this higher concentration is essential for effectively penetrating tough, established plants.

Horticultural vinegar of 10 to 30 percent acetic acid is highly acidic and corrosive. It can cause severe skin burns and permanent eye damage. It’s crucial to prioritize safety when using this solution to combat weeds. Always wear protective gear, including chemical-resistant gloves, splash-proof goggles, long sleeves, long pants, and closed-toe shoes to ensure your safety while spraying.

Read the original article on Martha Stewart