Vinegar may have a place in the arsenal of products that control garden problems, especially if you’re looking for non-chemical solutions. But using vinegar on or around your crops and ornamentals comes with risk.

In this article, we’ll explore how to use vinegar safely and effectively in vegetable and flower gardens.

Why Vinegar Can Be Useful in the Garden

Vinegar works as a contact herbicide that burns the leaves of young plants, interrupting photosynthesis and starving the roots. It can control small weeds with repeat applications, but it’s also non-discriminating, which means direct contact can damage any plant.

Other uses include pest repellent, soil boost for acid-loving plants, and powdery mildew control. Soaking hard-coated seeds in a vinegar solution before planting can improve germination, but can also inhibit germination in seeds sown directly in the ground.

The acetic acid in vinegar helps break down calcium into a form plants can use.

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5 Ways to Use Vinegar on Crops and in the Garden

Spraying vinegar directly on vegetable plants has little benefit and, if applied incorrectly, can do more harm than good. Avoid overuse in gardens, which can cause a rapid drop in soil pH, raising soil acidity, impacting beneficial soil organisms, and causing soil imbalance. Here are some safe ways to put vinegar to work in your garden.

• Weed Control: A vinegar and water dilution with a bit of dish soap works to kill young weeds. Avoid direct contact with desirable plants.
• Pest Control: Place vinegar-soaked rags or containers of vinegar-infused diatomaceous earth around garden perimeters to repel insect and animal pests. Use it to trap fruit flies and other winged insect pests in gardens and orchards.
• Lower Soil pH: For acid-loving plants that need a quick boost, vinegar rapidly but temporarily lowers soil pH. Apply a dilution directly to the soil around the plant. Test your soil first and use caution.
• Calcium Boost: All plants need calcium. Vinegar helps break down composted products like eggshells to release calcium in a form plants can use.
• Powdery Mildew: This fungus is endemic to broad-leafed crops like squash, melons, and cucumbers. Add two or three tablespoons of vinegar to one gallon of water in a spray bottle and use judiciously to avoid burning leaves.

5 Crops and Plants to Avoid Using Vinegar On

• Asparagus: Acidic soil can cause fusarium root rot, resulting in crop loss.
• Spinach: Seeds may not germinate, and young plants are stunted. Yellowing leaves are a sign of magnesium deficiency caused by acidic soil.
• Pole Beans: Acidic soil reduces the nitrogen-producing bacteria roots need for healthy growth, leading to small yields and stunted plants.
• Peas: Acidic soil reduces seed germination. It also inhibits nitrogen production, causing slow growth, stunting, and reduced yields.
• Pumpkins: Acidic soil interrupts and reduces the plant’s ability to take up necessary nutrients, resulting in weaker vines, smaller pumpkins, and vulnerability to disease.

How to Safely Use Vinegar in the Garden

Full-strength vinegar should be used only for pest control, and only in spray form for repelling ants and slugs. For all other purposes, it should be diluted with water. Vinegar solutions often include other ingredients like dish soap.

Use the correct ratio of vinegar to water for the application. If you are unsure, less vinegar is the better choice.

For weed control, apply a vinegar dilution on a dry, hot day for the greatest effect. To remedy a problem, such as powdery mildew, first test a single leaf to see if the concentration causes damage. Apply in the morning or evening when UV rays are diminished.