The Indian neem tree has been the subject of many recent pest control studies. Neem oil and neem oil products are approved under USDA organic regulations to be an effective and safe pesticide for use on organically grown fruits and vegetables.
Neem is not a pesticide with immediate knock-down results. It works on chewing and sucking insects and interrupts their basic instincts to eat, breed and lay eggs. Eating is interrupted soon after neem is applied, while other behavior disruptions may occur up to a few days later, if the insect is not already dead from starvation. Neem is non-toxic to humans and animals. Birds can eat debilitated insects with no ill-effects.
Apply Neem Oil to Plants
Use the correct amount of neem oil and water. Most neem oil garden products use one teaspoon of neem oil per one quart of water. That is four teaspoons of neem oil in a one gallon sprayer.
Do not use more neem oil than is recommended. A higher concentration is not more effective.
Fill your sprayer with a measured amount of warm water, and add a few drops of ecologically safe liquid dish soap and mix. Then add the neem oil and mix well.
Spray your plants, covering all sides of the stems and leaves. Shake your sprayer as you work to keep the solution well mixed. Neem spray is safe to use on food crops, and is safe on houseplants. It will not harm pets that might chew your houseplants.
Spray the soil surrounding your plants, too. The solution will be picked up by the plants' root systems and distributed throughout the plant.
Avoid spraying neem oil solution when the temperature is over 90 F. Spray during the cooler periods of the day, early morning or evening. If you use neem spray during hot weather, it can cause leaf curling.
Dispose of any leftover neem solution after you finish spraying. Do not keep it for later use, because it begins to break down within a few hours. Mix a new batch of fresh solution each time you need to spray.
Repeat the spraying once a week for five weeks.