The Best (Nontoxic) Pesticides and Insecticides, According to Gardeners

Four of our experts highly recommend Neem-oil, a natural insecticide derived from the neem tree. It’s Rogue’s “go-to treatment for most garden and houseplant pests,” andKrissie Nagy, owner of gardening companyBK Bumpkin, says, “It harms the biological and reproductive systems of insects but is completely safe to humans.” Of the many brands on the market, Deborah Young, owner of Brooklyn-based gardening storeSeasons, suggests Safer’s Neem-oil to her customers. This 16-ounce bottle of concentrate can make up to 16 gallons of spray by mixing it with warm, soapy water.

Diatomaceous Earth is a powder made from fossilized marine phytoplankton that’s harmful to insects with exoskeletons, but completely pet and human safe. Nagy says it’s especially helpful for dealing with a slug or ant infestation. But only “sprinkle it on a dry plant orplanter— it does not work as well on wet plants,” she cautions.

To combat gnats, Irene Kalina-Jones, owner ofOutside Space NYC, uses these double-sided sticky boards astraps. They’re an inexpensive, practical solution that she says is also oddly satisfying. “I get gleeful by seeing how many I get on the sticky card.”

To naturally fight off aphids — disease-spreading pests that feed on the sap of indoor and outdoor plants — Jesse Terzi, co-founder of landscape andgarden designfirmNew Eco Landscapes, recommends using nematodes in the soil of indoor or outdoor plants. The parasitic roundworms attack more than 200 different species of pests, and are entirely harmless to pets and wildlife. Nematodes are “natural predators to grubs and other insects that live in soil,” according to Rogue. “They are part of the natural order of the environment that we can harness to defend our gardens.”

Three of our experts suggested releasing live ladybugs as another naturally effective way to fight off aphids — “the peskiest pests in New York,” says Nagy. Amazon’s inexpensive bag contains 1,500 live ladybugs, which will feast on the aphids plaguing your houseplant orgarden.

Rogue also likes using the praying mantis as a natural pest killer. Not only do they eat the harmful bugs, “but it can be a fun science lesson for kids, and releasing the insects is exhilarating.” This kit comes with two egg cases that each can hatch between 50 to 200 live babies. The results can be a little mixed because the bugs can fly away, but Rogue says it’s nice knowing that “wherever these little guys go, they are benefiting ourenvironment.”

To get rid of molds, mildews, and fungus, Rogue uses Dr. Earth’s Disease Control Fungicide. The formula is a comprised ofessential oils, garlic extract, and acids that destroy these pests on contact. Plus, the solution’s “natural rosemary and clove oils smell fantastic,” she says.

When it comes to weeds, “the best killer is your hands,” says Nagy. That’s because most weed killers will not only harm humans but also kill off earthworms and destroy your soil’s ecosystem — which is important to maintain for healthy gardens. When her bare hands just won’t do, Nagy mixes a gallon of vinegar with a tablespoon of table salt and soap to spray on weeds — but only those growing “onpatiosand in between pavers because it will kill anything it comes in contact with. Weeds will dry out and die after two to three days.”