Pest-Controlling Oils

Today's horticultural oils are effective, low in toxicity and can be applied just about any time of year.

Products made from various oils have been used in the garden for centuries. Ancient Romans used mineral oil to control plant pests, while the American colonists relied on whale oil.

Beginning in the 1930s, the oil of choice was a petroleum product known as dormant oil, so named because it was applied during the dormant season. It was used primarily to control scale insects and mites on dormant trees and shrubs.

Today new superior oils – also called highly refined oils or simply horticultural oils – have replaced dormant oil. They’re effective, low in toxicity and much lighter (that is, not as viscous). These oils can be applied just about any time, even during the growing season, and control not only pests but various diseases too, in particular fungal diseases.

The key to using horticultural oils during the growing season is to make sure the plants you’re spraying aren’t water stressed; if they are, some damage could occur. So simply water the plant well the day before you spray.

Neem oil is an excellent product for controlling pests and diseases. "It’s derived from the tropical neem tree," says Paul James, "and it works better than any other oil-based formulation I’ve ever used."

Within the category of herbicides, new products seem to pop up every year, says Paul, including one introduced in 2005 that is made from clove oil. "In my experience, these oils control weeds best when temperatures are warm, say in the 80s or 90s," he says.

horticultural oil (Concern/Necessary Organics) - Woodstream Corporation
clove oil - St. Gabriel Laboratories
neem oil - Safer Brand

Next Up

Avoiding Pests and Disease in the Garden

Paul James reveals his secrets for controlling pest and disease problems.

Garden Invaders

Be on the lookout for these invasive pests and learn how to avoid them.

Controlling Garden Pests Indoors

Follow this indoor gardening tip to keep the garden pests away.

Effective Fungicides

Got fungal disease on your favorite garden roses or vegetables? Master gardener Paul James offers simple and easy-to-use fungicide treatments to resolve these pesky problems.

Find Garden Remedies in the Kitchen

Learn how to combat garden pests with common items from the kitchen.

Live With Critters in the Garden

Learn how to coexist peacefully with the various creatures who love your garden.

Q&A: Eastern Lubber Grasshopper

Here's a tip on how to control eastern lubber grasshoppers.

Mystery Critter: Scale

This quiet, immobile insect can wreak havoc on certain plants.

How to Get Rid of Gophers, Moles and Armadillos

Learn how to drive off unwanted underground garden guests with these expert tips.

Common Agave Pests

Plants that seem the most cast iron can indeed have an Achilles' heel. Just like so many mighty giants of history it is often the littlest things that ultimately bring them down.

Go Shopping

Spruce up your outdoor space with products handpicked by HGTV editors.

What's New in Outdoors

On TV

Home Town

7am | 6c

Home Town

8am | 7c

Home Town

9am | 8c

Home Town

10am | 9c

Home Town

11am | 10c

Home Town

12pm | 11c

Home Town

1pm | 12c

Home Town

2pm | 1c

Home Town

3pm | 2c

Home Town

4pm | 3c

Home Town

5pm | 4c

Home Town

6pm | 5c

Home Town

7pm | 6c
On Tonight
On Tonight

Home Town

8pm | 7c

Home Town

9pm | 8c

Home Town

10pm | 9c

Home Town

11pm | 10c

Home Town

12am | 11c

Home Town

1am | 12c

Home Town

2am | 1c

Home Town

2:59am | 1:59c

Follow Us Everywhere

Join the party! Don't miss HGTV in your favorite social media feeds.