We Asked Gardeners About Using Garlic in the Garden—Here’s What Actually Works

People widely use garlic for its many proven health and medicinal benefits, but can it benefit other plants? Its compact size and cold-hardy properties mean it’s worth growing garlic as a companion plant that slots handily into a year-round crop rotation plan for your vegetable garden.

There are also widely shared home garden hacks espousing the benefits of using garlic-infused water to boost soil nutrient levels for other plants and protect them from pests.

We asked the experts whether there is science to back up these claims and, if so, how to use garlic for plant health purposes.

Using Garlic Water for Happier Plants

Have you seen the TikTok trend recommending crushing garlic cloves, mixing them with water, and pouring the solution into soil to feed your plants? It might sound like a simple natural fertilizer option, but the experts are unconvinced.

“While garlic contains many of the nutrients that plants need to grow, you’d have to use a lot of garlic to fully meet those needs,” Peyton Ginakes, a fruit and vegetable research associate at the University of Maine Extension, says.

She explains that some compounds in garlic could benefit plant growth indirectly by stimulating microorganisms near roots, but other natural, scientifically backed solutions would be a safer bet. Consider manure tea, bone meal, or fish emulsion instead.

Using Garlic for Pest Control

There’s more encouraging evidence supporting the use of garlic as a plant pest repellant. However, Nicole Sanchez, an Associate Professor of Practice in the Department of Horticulture at Oregon State University, cautions that it isn’t a one-size-fits-all solution. 

“It can’t be a silver bullet, it’s not going to work for every situation, and we’re still learning where it’s effective and where it’s not,” Sanchez says.

The method, concentration, and timing of application could also influence the success of the repellent.

Interplanting

If you’re having problems with pests decimating your crops, consider interplanting them with garlic to see if it helps keep the bugs away.

However, while a study showed that spider mite populations were suppressed when growing eggplants alongside garlic, be aware that you might not have the same success when planting different crops and dealing with different pests.

Spray Solution

If you want to ditch the chemical insecticides, try adding three to five crushed garlic cloves or a few drops of garlic essential oil to 300 ml of water and spraying this directly into your plants. 

Sanchez recommends avoiding using neat essential oils or applying the spray in the heat of the day.

“This is more likely to have some kind of burning effect,” she says. Some studies also suggest it is more effective when applied at night. 

Recipes often suggest adding dish soap and vegetable oil to this DIY pest repellent to better blend the ingredients and help it adhere to plant leaves. However, Lois Miklas, a Penn State Master Gardener, cautions against using dish soap.

“It is not your grandmother’s homemade lye and tallow mixture, but a detergent that is not intended or tested for use on outdoor plants,” she says. Dish soaps may contain chemicals that are harmful to the environment or plants. 

Because research is limited, it’s difficult to confirm which plant and insect combinations (and insect life stages) this solution could be effective for. However, provided you don’t apply at the wrong time or with an overly strong mix, it is unlikely to do any harm if you want to experiment. Also, be aware that studies suggest neem is a more effective natural pest repellent.   

Some pests that studies suggest garlic could be an effective repellent against include:

• Aphids
• Cabbage flies
• Caterpillars
• Cowpea insects
• Gall midges
• Maize weevils
• Slugs and snails
• Spider mites
• Tomato pinworms