As with anything applied to plants, it is important to read the entire label and carefully follow the directions. Insecticidal soaps are usually used as a 1 to 2% solution (2½ to 5 tablespoons per gallon). Always follow the label for the product you are using. Do not attempt to use it in higher concentrations, as this may be very harmful. Mix the soap concentrate in a clean sprayer. Do not apply the soap in full sun or at temperatures above 90 ºF as this may damage the plants. High temperatures and high humidity may increase plant stress and, therefore, sensitivity. It is best to treat your plants in the early morning or late in the day. Since the soap spray is only effective as long as it is wet, the slower drying conditions favor better insect or mite control.

It is important to spray both the top surface and, especially, the underside of the leaves as many of the pests will be found there. Because of the relatively short residual action and the fact that the insects must be in contact with the soap to be effective, repeat applications may be necessary every 4- to 7-days (follow the label directions) until the pests are eliminated. Avoid excessive applications as leaf damage may accumulate with repeated exposure. Always follow the directions on the label.

The quality of the water you are using should be considered when using insecticidal soaps. Hard water reduces the effectiveness of the insecticidal soap. Calcium, magnesium, and iron cause the fatty acids to precipitate out of the solution causing the soap to be ineffective. It is important to use the purest water possible. You can determine if your tap water is compatible by mixing the recommended concentration of soap that you want to use with the appropriate amount of water in a glass jar. Agitate and let the mixture stand for 15 minutes. If the mix remains uniform and milky, the water quality is fine for the spray. If there is scum on the surface, you should use distilled or bottled water.