Will Mothballs Harm Outdoor Plants? What You Need To Know

When searching for a solution to the pest problem in my garden, I came across several recommendations, including the use of mothballs. I wanted to know more about mothball’s effectiveness as a pest repellent and the possible side effects on my plants.  

Mothballs will harm outdoor plants due to toxic chemicals like naphthalene, or paradichlorobenzene. These chemicals contaminate soil and groundwater, damaging plant roots and stems. Mothballs are more harmful to potted plants because the chemicals remain within the soil for long. 

Although mothballs repel pests, the label specifies their usage in closets for a reason. This article will analyze the impact of mothballs in your garden and why you shouldn’t use them. 

Are Mothballs Safe for Use in the Garden?

Pests are a menace in the garden, and most gardeners prefer to repel them before they attack their plants. There are several pest repellents, both homemade and commercial, that you can use in your garden. However, there are a few concerns about using mothballs in your garden. 

Mothballs are not safe for use in the garden because they contain chemicals that plants will absorb. Naphthalene and paradichlorobenzene are carcinogenic, and they will get into groundwater and the soil. The chemicals get into plants too and put your health at risk when you consume affected vegetables.

Before using mothballs in your garden, you should read the label to verify where to place them. Many people use mothballs in the garden because they are known to repel pests. However, the risks are high.

This video analyzes the negative effects of mothballs in your garden:

Why You Shouldn’t Use Mothballs in the Garden

Mothballs have a strong odor that many people find unappealing. The assumption is that the smell will keep pests away from your garden.

While this is true, there are many reasons why you shouldn’t use mothballs in your garden:

Contain Naphthalene or Paradichlorobenzene

Mothballs have naphthalene or paradichlorobenzene as the active agent. These chemicals are suspected of causing cancer. The International Agency for Research on Cancer (IARC) performed animal tests and found conclusive evidence showing that Naphthalene is carcinogenic. 

Naphthalene changes from solid to toxic gas fumes, causing nausea, headaches, and dizziness. The gas is what repels animals and kills insects. When ingested, naphthalene also breaks down into alpha-naphthol, which can cause kidney and liver damage.

It takes mothballs anywhere between 2 months and 1 year to dissolve fully. How fast the mothballs evaporate will depend on the temperature, air movement, and moisture levels.  

Paradichlorobenzene is less toxic than naphthalene. However, it can still cause skin irritation, nausea, fatigue, and dizziness. 

Wet Mothballs Are More Toxic

Wet mothballs are more toxic than dry mothballs. In the garden, the mothballs get wet. As a result, the odor becomes more pungent, and the chemicals get into the soil much faster.

Plants Absorb Leached Chemicals

The chemicals in mothballs leach into the soil and groundwater and are absorbed by plants. If you use the water in your vegetable garden, the plants may get contaminated. The chemicals also destroy plant roots, which may ultimately kill the plants.

Pets & Children Are at Risk

Placing mothballs in your garden will do more harm than good, especially if you have children and pets.

Pets may be tempted to eat mothballs when they are out in the garden. Fortunately, naphthalene breaks down into elements that get released from the body via urine. The effects are more severe when large quantities of naphthalene are consumed. 

Mothballs are colorful, and children can easily mistake them for candy. Once they put the mothballs in their mouths, they’ll ingest toxic chemicals that will have long-term effects if they don’t receive treatment on time. Some of the immediate effects include diarrhea, fever, and abdominal pain. 

Repelling Useful Insects

Mothballs may repel some pests, but they also keep helpful insects, such as bees and butterflies, from the garden. Pollinators are important for a healthy garden, so mothballs will harm your garden. 


Naphthalene is flammable. This is why paradichlorobenzene is replacing naphthalene as the primary ingredient in mothballs.

Interestingly, both chemicals share the same NFPA 704 inflammability code. However, paradichlorobenzene is considered safer than naphthalene.

The Chemicals Are Pesticides

The chemicals in mothballs are listed and regulated as pesticides. Any improper use, such as illegally using them in the garden, may have legal ramifications if it negatively affects animals and wildlife. 

Banned in Many Places

Naphthalene mothballs are still available in the US market.

However, they are banned in several countries because of their high toxicity, including:

  • The European Union
  • The UK
  • New Zealand
  • Australia

Will Mothballs Repel Pests in the Garden?

Despite the challenges of using mothballs in the garden, they remain effective pest repellents. They get rid of moths, their eggs, and larvae in the closet and on fiber. Some people choose to use them in the garden, but do they repel outdoor pests?

Mothballs will repel pests in the garden because of their strong smell. Squirrels, mice, rats, snakes, raccoons, and moles find the scent of mothballs repulsive. In the open air, the smell lasts for months. However, it doesn’t repel all pests, and the strength diminishes over time. 

Mothballs work as pest repellents in the garden. Unfortunately, they only work on pests sensitive to the strong smell.

Pests, such as ants and spiders, are not easily put off by mothballs. Some insects will also attack the garden, even when you have mothballs all over the garden. 

This video shows the pests and animals repelled by mothballs:

How to Use Mothballs in the Garden Safely 

Mothballs may carry an element of risk in the garden, but they are still effective pest repellents. If pests and animals, such as squirrels, mice, and raccoons, are giving you a difficult time, you can repel them with mothballs.

You’ll need to take measures to minimize the potential side effects:

Set a Far-Away Boundary

Set a boundary, far from your plants, especially if you are using the mothballs in a vegetable garden. The mothballs will repel pests and animals from the garden. You will also be protecting your plants from coming into direct contact with the mothballs.

Put Them in a Container

Instead of leaving the mothballs all over your garden, put them in a bag or container. This is one way to keep your soil safe from contamination. Pests and animals with a strong sense of smell will still smell the mothballs and avoid your garden. 

If you have to use mothballs in your garden, it should be a short-term solution as you seek a safer pest control method. You should also avoid using mothballs in the garden if you have children or pets. 

Alternative Pest Repellents for Your Garden

The risks of using mothballs in your garden far outweigh their benefits. Besides having some level of success as pest repellents, mothballs are toxic to the soil, underground water, children, and pests. Before using them in the garden, it is best to consider the alternatives.

Here are alternative pest repellents you can use on pests in your garden instead of mothballs:

PestsPlant DamageControl Method
  • Curled leaves and flowers
  • Suck sap
  • Hose down the plant.
  • Cut off the affected stem.
  • Apply insecticidal soap.
  • Plant dill, mint, clover, and fennel to attract beneficial insects, like ladybugs.
  • Mix peppermint, rosemary, thyme, or clover essential oils
  • Feed on leaves and stems
  • Set up a birdbath to attract birds to your garden. Birds eat caterpillars.
  • Refresh the water in the birdbath daily.
  • Spray your plants with an organic insecticide.
Flea beetles 
  • Holes in leaves
  • Parasitic wasps are natural predators.
  • Use flea beetle control pesticides.
Japanese beetles 
  • Feed on leaves heavily, leaving behind leaf veins
  • Hand pick the beetles.
  • Use pesticides.
  • Apply chemical treatments to kill grubs.
  • Liquid dish-washing solution mixed with vegetable oil and alcohol.
  • Sucks sap and distorts the shape of leaves
  • Leaf loss
  • Stunted growth
  • Secretes honeydew and attracts ants
  • Sooty mold growth
  • Grow sweet alyssum and yarrow flowers.
  • Apply alcohol-dipped cotton swabs on affected leaves.
  • Use insecticidal soap or neem oil.
  • Prune the plant for light infestations.
  • Avoid overwatering your plants.
  • Don’t over-fertilize your garden. Mealybugs prefer gardens with high nitrogen levels.
Snails and slugs 
  • Holes in leaves and flowers
  • Shiny, slimy trails
  • Snail baits with iron phosphate
  • A dish filled with beer
  • Copper and salt barriers
  • Spread coffee grounds around the garden
Garden pests, plant damage, and control measures. 

You can also plant lavender, thyme, rosemary, mint, and cedarwood. These are natural pest repellents that will be just as beneficial as mothballs, but without the risks. 

Another good alternative is insecticidal soap. Most available products are ready-to-use organic insect and pest repellents for use on mealybugs, leafhoppers, aphids, thrips, whiteflies, and psyllids. Insecticidal soap works well on vegetable and flower gardens, trees, fruits, and ornamental plants.


Mothballs work as insect repellents, but only for the specified use indicated on the label. They are not designed for use outdoors, especially not in your garden. Unfortunately, this is a go-to-repellent for many people because they are within easy reach and repel some pests and animals from the garden. 

The risks of using mothballs may not be worth using them in your garden, especially if you are putting the lives of your pets and children at risk. Instead, you should consider safer alternatives that work on the pests without harming beneficial insects in the garden.

Alexander Picot

Alexander Picot is the founder of TheGrowingLeaf.com and its lead content writer. He created the website in 2022 as a resource for horticulture lovers and beginners alike, compiling all the gardening tips he discovered over the years. Alex has a passion for caring for plants, turning backyards into feel-good places, and sharing his knowledge with the rest of the world.

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