Horticultural Oil

Tier A — Proven Safe Mineral / Physical

Quick Facts

Type
Mineral / Physical
Source
Highly refined petroleum oil or plant-based oils (soybean, cottonseed); modern formulations are "superior" or "supreme" grade
OMRI Listed
No
Bee Safe
Yes
Pet Safe
Yes
Residual
No residual once dried — safe for beneficials after dry
Best For
Dormant-season application on fruit trees (smothers overwintering eggs and scale). Summer use on active infestations.

What Is Horticultural Oil?

Suffocates insects and eggs by blocking spiracles (breathing pores) and disrupting cell membrane function. Physical mode of action — no resistance development possible. Also dissolves the protective wax coating on scale insects.

Source: Highly refined petroleum oil or plant-based oils (soybean, cottonseed); modern formulations are "superior" or "supreme" grade

What Pests Does Horticultural Oil Kill?

Horticultural Oil is effective against the following pests:

Aphids Whiteflies Spider Mites Scale Insects Mealybugs Codling Moth

How to Apply Horticultural Oil

Best for: Dormant-season application on fruit trees (smothers overwintering eggs and scale). Summer use on active infestations.

Avoid for: Stressed plants, extreme temperatures, within 30 days of sulfur application.

Residual activity: No residual once dried — safe for beneficials after dry

Safety Profile

CategoryRating
Bee Safety 🟢 Safe for bees
Pet Safety 🟢 Safe for pets
Overall Rating Safe — Safe for kids, pets, and bees when used as directed

Why Isn't Horticultural Oil Working?

If Horticultural Oil isn't delivering results, check these common failure modes:

Temperature extremes — do not apply below 40°F or above 90°F

Drought stress — oil can burn water-stressed plants

Sulfur interaction — never apply within 30 days of sulfur treatment

Blue spruce and similar waxy conifers may be damaged

Best Horticultural Oil Products

Bonide All Seasons Spray Oil

Concentrate

Year-round use, highly refined petroleum

Monterey Horticultural Oil

Concentrate

Paraffinic oil, lightweight formulation

Organocide Plant Doctor

Concentrate

Soybean-based alternative — plant-derived

Sources and Further Reading

Related Ingredients

Bacillus thuringiensis (Bt)

Tier A

Bacillus thuringiensis (Bt) is the most proven organic caterpillar control available. This naturally occurring soil bacterium produces proteins that destroy caterpillar gut linings within 24-72 hours while remaining completely safe for bees, pets, and beneficial insects.

Spinosad

Tier A

Spinosad is a naturally derived insecticide that kills thrips, caterpillars, leafminers, and fire ants through nervous system disruption. OMRI-listed and effective, but must be applied in evening hours to protect pollinators.

Insecticidal Soap

Tier A

Insecticidal soap kills aphids, whiteflies, spider mites, and mealybugs on contact by disrupting their cell membranes. It has zero residual toxicity, is safe for bees and pets, and can be made at home with pure castile soap.