How to Kill Dandelions With Vinegar
Dandelions (Taraxacum officinale) can make even the most seasoned home gardener shudder with loathing. On paper, dandelions are fascinating: The versatile plants are edible and have been used for medicinal purposes for hundreds of years. In reality, the weeds are often a great nuisance.
Tenacious and difficult to eradicate, they spring up seemingly overnight in lush lawns and colorful flower beds. One effective way to kill them is to douse them with acidic vinegar as soon as you see the first leaves appear.
Think twice about using the vinegar in a kitchen cupboard to kill dandelions. Although convenient, household vinegar usually has a concentration of about 5 percent, which is not nearly as effective at killing weeds as more concentrated vinegars -- unless used during the first two weeks of the plant's growth. The acidic property of vinegar is what enhances its effectiveness as a weed killer: It literally eats away at weeds. For this reason, the more acidic the vinegar, the better. Horticultural-strength vinegar, which has a much higher percentage of acid, is much more effective, according to Purdue University. Look for vinegars labeled for herbicidal use for maximum effectiveness -- these are much stronger, with a concentration of 11 percent or higher.
Anyone who's ever yanked on a dandelion knows that getting it out of the ground isn't an easy task. One reason dandelions are so tenacious is because they have long, strong taproots. Leave even a small but healthy portion of the root in the ground, and a new flower will spring up where the old once was. Killing the root is the key to eradicating these pesky plants. Vinegar is not transferred from the leaves to the roots -- it only eats away at the leaves and stem. For this reason, repeated applications of vinegar may be needed to make sure new plants don't grow. Eventually, the food stored in the root will be depleted, and the root will not re-sprout again.
The closer you can get to the root, the better. Protect your hands and eyes with gloves and goggles, and wear long sleeves as strong concentrations of vinegar can burn the skin and irritate the eyes. Apply straight, undiluted vinegar directly to the base of the plant with a spray bottle on a cool, still day, when rain is not in the forecast for at least 48 hours. Rain can dilute the vinegar, and if it rains shortly after application, you will need to re-apply the spray. The best time to apply vinegar is as soon as you see leaves appear. The younger the plant, the more easily it will be killed. Mature plants that have flowers will require multiple applications of vinegar.
Tips and Warnings
Vinegar is not selective: It will kill any nearby plants and grasses it touches. For that reason, take precautions to protect desirable plants. Cover them with plastic so they don't get inadvertently sprayed. Vinegar will even eat away at cement, so protect nearby structures and sidewalks as well and resist the urge to spray vinegar on hardy dandelions forcing their way through the cracks in the concrete. Instead, yank them out by hand.