How to Use Soap in the Garden to Deter Pests, Kill Weeds, and More

When reflecting on all the wondrous things soap can do, you might think only about the odd jobs around the house, from cleaning dishes to mopping your floors. But soap isn’t just for keeping your home spick and span; it can help tidy up your garden as well. From deterring pests to killing weeds, soap has a variety of uses in the great outdoors. Ahead, we share garden experts’ recommendations for how to use soap in your garden and yard.

Deter Animals From Your Garden

Many animals are sensitive to smells. This includes critters like deer, squirrels, and rabbits, which can be pests in the garden, as they munch on vegetables and dig up bulbs. By using strongly scented bars of soap, such as Castile peppermint soap, you can make the environment unpleasant, says Lucie Bradley, a gardening and greenhouse expert at Easy Garden Irrigation.

Simply cut the soap into blocks, place them in mesh bags, and hang them around your plants from stakes. Position the soap at the correct height for the animal you wish to deter. "For deer, suspend about 3 feet off the ground, whilst for rabbits, bags of soap should be hung 1 to 2 feet from the ground," Bradley says.

Kill Insect Pests

Dishwashing soap can help rid your garden of insect pests. Simply fill a spray bottle with 1 tablespoon of dish soap and water, and you have a method for removing garden pests like aphids, thrips, mites, and whiteflies, says Bradley. "You just need to make sure that you locate and spray the pests whilst they are on your plants—checking the underside of plant leaves is a good place to start," she says. But be aware that your spray can’t distinguish between pests and beneficial insects, she adds. Be careful not to spray beneficial garden insects, like pollinators, with your spray.

Remove Moss

While moss has many benefits, excess moss on pathways can lead to slippery surfaces, posing a safety hazard. To remove the moss on hard surfaces, combine 4 to 5 ounces of dish soap with 2 gallons of water in a sprayer, says Steve Corcoran, lawn care expert and CEO of Lawn Love. After making this solution, apply it directly to the moss, fully saturating it. "After about a day of letting it work away, you should be able to easily remove the moss by raking it and then disposing of it," he says.

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Kill More Weeds

If weeds are taking over your garden, consider making an all-natural solution using dish soap rather than turning to synthetic herbicides. You can make a DIY weed killer by combining 1 gallon of vinegar, 1 tablespoon of dish soap, and 1 cup of salt. "Adding dish soap to the mixture helps by making the solution spread more evenly and stick to weeds more effectively," says Corcoran.

Reduce Plant Diseases

A spritz of soap and water won’t prevent plant diseases, but it will reduce the chances of some diseases spreading by cleaning plant foliage and killing the insects that cause them. "When pests are feeding on the sap of your plants, they leave behind a sticky substance on the foliage, called honeydew," says Bradley. This sugary waste forms the perfect environment for various fungi to grow, which results in sooty mold, she says.

Using a mixture of soap and water on the plant foliage softens and washes away the sooty mold and sticky honeydew. Removing the honeydew leaves nothing behind for the fungi to feed on and kills insects in the process. It’s a win-win.

Mistakes to Avoid

Using soap in the garden has plenty of benefits. Still, there are a few mistakes to avoid.

Not Diluting the Soap

Dilute soap with water before using it in your garden. Soap is a base, an alkaline substance, and so using high concentrations of soap can burn foliage and may alter the pH balance of your soil. By using a diluted version, a mix of soap and water, the soap’s effects are reduced, protecting the plants from potential harm.

Forgetting to Reapply

When using bars of soap to deter pests, don’t forget to reapply the soap, says Bradley. "You will need to replace the soap over time as the scent will reduce in strength, and if it rains, the odor will be washed away faster," she says. Replace the soap monthly for optimal effectiveness.

Using Soap with Bleach

Never use a dish soap that contains bleach, moisturizer, or synthetic fragrances, as these can harm your plants.