Why You Should Never Use Mothballs in the Garden

Several small spherical objects likely mothballs on a wooden surface with a plate partially visible in the background — Credit:
Getty Images

Using mothballs in the garden is harmful to the environment, pets, and people, and it's often illegal.
Mothballs release toxic chemicals that dissipate outdoors, making them ineffective at repelling pests in open spaces.
Safer pest control options include planting pest-deterring plants, using physical barriers, and maintaining a clean, healthy garden.

Mothballs have been used in one form or another since the 1800s, primarily as a means to prevent insects and rodents from damaging clothes. These small spheres work by releasing a pesticide into the air, typically either naphthalene or 1,4-dichlorobenzene. Both emit a strong, sweet odor. Somewhere along the line, people began using mothballs in the garden, hoping that they would repel pests there too. Unfortunately, however, this isn't the best idea—here's why.

Teri Speight, landscape gardener, gardening coach, podcast host, and co-author of The Urban Garden
Christy Wilhelmi of Gardenerd and author of High Yield Small Space Organic Gardening

Dissipate in the Open Air

Using mothballs effectively requires storing them in an airtight space, as they dissolve directly into the air. When this process takes place inside a plastic tub—as required by the directions on the mothball package—the mothball gases are able to accumulate and circulate around the clothing they're intended to protect. As a result, any larvae living in this contained environment will soon be overwhelmed by the pesticide.

Now, think about what happens if mothballs are used in the garden, out in the open air. Their chemicals will simply dissipate to fill the area around them—which, outdoors, is enormous. It won't be a high enough concentration to have any useful effect.

Instead, they simply pose a risk to their environment and the living things in it. "Mothballs contain a neurotoxin called 1,4-dichlorobenzene, which is dangerous to our central nervous system," says author Christy Wilhelmi. They shouldn't be used anywhere in your garden.

Harm Wildlife

If used in a garden, mothballs can expose helpful insects, mammals, pets, and people to harmful chemicals.

"In many states it's illegal to use them in the garden," says gardening coach and author Teri Speight. "They are a carcinogen and are designed specifically for indoor use only." Plus, their interesting odor and bright white color will easily attract non-targets.

Damage the Environment

The directions on mothball packaging will explain exactly how the product should be used and what shouldn't be done with them—including a warning about outdoor use. Follow these instructions!

"Mothballs are known to contaminate not just the soil, but also underground water," says Speight. "Homeowners can be fined if found using mothballs in Maryland and other states."

Alternatives to Mothballs

Luckily, there are plenty of other options for deterring garden pests through odor or barriers.

Try Strong-Smelling Plants

Consider planting some pest-deterring plants nearby, like alliums or marigolds. "Strong-smelling herbs can be a deterrent for some critters," adds Speight.

Adjust the Environment and Use Physical Barriers

If you're struggling with pests, then you may need to re-evaluate your garden's overall health.

"I always recommend building an ecosystem that supports beneficial insects and using physical barriers to keep larger critters from eating our garden harvest," says Wilhelmi. "Floating row covers, hardware cloth, and chicken wire cages do a great job keeping curious animals out of the garden."

Keep Things Tidy

A clean garden can be a healthy one. Speight recommends removing piles of brush around your home's foundation and keeping grass cut low.

Why You Should Never Use Mothballs in the Garden—and What to Try Instead