A Guide to Common Organic Garden Pesticides

Vegetable garden

W. Atlee Burpee & Co.

It would be nice if no pesticides were necessary for the garden, but problems do occur. Left unattended, insects can ravage leaves, flowers and fruits and quickly spread disease. When a problem is severe enough to need control, always reach for the least toxic option first. That can be removing pests by hand or using an organic pesticide like the ones profiled here.

Remember, just because a pesticide is organic doesn't mean it does no harm. Always follow the label directions and keep in mind that more is not better, even with organic products.

Keep a close eye on your garden and try to catch problems early. If you practice good integrated pest management, with a wide range of plants, good growing conditions, natural predators, like birds and beneficial insects and healthy soil, you should not need to reach for a spray very often.

Insecticidal Soap

Ingredients: Insecticidal soap is sodium or potassium salts combined with fatty acids

Application: Insecticidal soap must come in direct contact with the insect. It is no longer effective once it has dried

How It Works: The fatty acids in the soap penetrate the insect’s outer covering and cause the cells to collapse


  • One of the safest pesticides
  • Non-toxic to animals
  • No residue
  • You can use on vegetables up to harvest


  • Can burn or stress plants. Don’t use in full sun or high temperatures.
  • Does not work well for adult beetle pests which have developed a hard shell.

Precautions: Check label for specific plants that may be sensitive to insecticidal soap

Diatomaceous Earth

Ingredients: Silica from the skeletons of tiny aquatic animals.

Application: Powder that is dusted on plants. May also be available in wettable powder or spray form.

How It Works: Absorbs fats and oils from the insect's exoskeleton causing it to dry up and die. Sharp edges help to pierce the insect allowing the powder to work quickly.

Pros: Remains active for a long period as long as it is kept dry.

Bacillus Thuringiensis

Bt (Bacillus thuringiensis)

Ingredients: bacteria. There are more than 80 types of Bt used as pesticides

Application: Generally available in powdered form that is sprinkled or dusted on a plant. It must be eaten by the targeted insect

How It Works: Bt is a stomach poison. It releases toxins in the stomachs of susceptible insects which cause them to stop eating and starve

Pros: Bt strains are very host-specific (hornworms, corn earworms, cabbage loopers and other caterpillar pests) and will not harm people, pets, birds or bees

Cons: Slow acting. It may take days for the insect to completely stop eating and die. Breaks down quickly, especially sunlight. Can kill ‘good insects’ like butterfly larva.

Precautions: Follow the label directions and don't overuse it


Ingredients: Contains 2 ingredients, azadirachtin and salannin, both from the seed kernels of the neem tree fruit

Application: Sprayed onto plant leaves

How It Works: Upsets the insects' hormonal system and prevents it from developing to its mature stage. Most effective on immature insects

Pros: Non-toxic to humans

Cons: Washes away in rain. Slow acting. Breaks down in sunlight. Indiscriminate pesticide

Precautions: Keep pets from treated leaves until they dry

Horticultural Oil

Ingredients: Highly refined petroleum oil

Application: Mixed with water and sprayed onto foliage

How It Works: Coats and suffocates insects or disrupts their feeding

Pros: Low toxicity to humans, pets or birds. No toxic residue

Cons: Most effective against soft-bodied insects. Can cause bluish evergreens to temporarily lose their blue tint. Can burn leaves

Precautions: There are several grades. Be sure to use the one that is right for the season in which you are spraying


Ingredients: Derived from Chrysanthemum cinerariifolium

Application: Generally found in powder form and dusted on leaves.

How It Works: Poisons the insect, causing a quick death

  • Pros: Quick acting. Low toxicity to animals. Degrades within a day.
  • Cons: Broad spectrum insecticide. Kills any insect. Very toxic to honeybees

Precautions: Use cautiously, only when you have a major problem with hard-to-kill insects


Ingredients: Ground seeds of the sabadilla lily

Application: Comes as a fine powder and used as a spray

How It Works: Acts as a stomach poison

Pros: Very effective against the true bugs (members of the Hemiptera order)

Cons: Highly toxic to bees. Very irritating to the mucous membranes of mammals

Precautions: Use as a last resort


Ingredients: Derived from the roots of tropical legumes

Application: Dust onto plant

How It Works: Inhibits a cellular process, depriving insects of oxygen in their tissue cells

Pros: Low residual effect. Breaks down quickly in sunlight

Cons: Broad spectrum pesticide. Mildly toxic to humans when ingested.

Precautions: Apply in the evening, when bees are less active. May specify a "wait" interval before harvesting.

Potassium Bicarbonate

Ingredients: Potassium bicarbonate usually combined with horticultural oil and/or a substance to improve spreading and coverage of the leaves. There are commercially available products such as GreenCure® and Kaligreen, or you can prepare your own.

Application: Spray at the first sign of disease or use as a preventative before infection

How It Works: It’s still unclear, but it appears that bicarbonates can damage the cell wall and possibly create a pH that is not conducive to further fungal growth. The effect is immediate


  • Lasts 2 - 3 weeks as a preventative
  • You can use on vegetables up to harvest

Cons: Can burn plants, especially if used in full sun

Precautions: Check label and test on a small area before spraying the entire plant


Make sure you are using the correct control for the pest you want to eliminate. Applying any pesticide late in the day will help reduce exposure for beneficials and pollinators. Always read and follow the label instructions and cautions.

Article Sources
The Spruce uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Profiles of Organic Pesticides.” OSU Extension,

  2. Potassium Salts of Fatty Acids. Oregon State University Extension

  3. Insecticidal Soap. Penn State University Extension

  4. Insecticidal Soaps, University of Connecticut Home & Garden Education Center

  5. Diatomaceous Earth, National Pesticide Information Center

  6. Bacillus thuringiensis (Bt). National Pesticide Information

  7. Bacillus thuringiensis (Bt) General Fact Sheet, National Pesticide Information Center

  8. Bt microbial insecticide, Minnesota Department of Natural Resources

  9. Progress on Azadirachta indica Based Biopesticides in Replacing Synthetic Toxic Pesitcides, National Center for Biotechnology Information

  10. Neem Oil General Fact Sheet, National Pesticide Information Center

  11. What should neem be used for on plants?, University of New Hampshire Extension

  12. Horticultural Oils – What a Gardener Needs to Know, University of Nevada, Reno

  13. Horticultural Oil, University of Connecticut Home & Garden Education Center

  14. Horticultural Oil, University of Connecticut Home & Garden Education Center

  15. Spruce Gall Adelgid, University of Connecticut Home & Garden Education Center

  16. Pyrethrins General Fact Sheet. National Pesticide Information

  17. PYRETHRINS, National Pesticide Information Center

  18. Natural Pesticides, Brooklyn Botanic Garden

  19. Botanical Insecticides. Texas A&M University Extension

  20. Natural Pesticides, Brooklyn Botanic Garden

  21. Toxicity of Pesticides to Pollinators and Beneficials, University of Massachusetts Extension Fruit Program

  22. Rotenone Can Remove Undesirable Fish From a Pond, Noble Research Institute

  23. Using Organic Fungicides. Purdue University Extension