Can You Spray Plants With Alcohol?

Alcohol Types

• All alcohols, if in high concentration, are harmful to living things, including plants. Ethyl, methyl, rubbing and butanol are a few types of alcohols that may already exist in the home in various cleaning or disinfecting agents. Ethanol is an edible form of alcohol that is found in lower concentrations in beverages. While the molecular structure varies slightly among alcohols, they all can potentially harm plant tissues at improper levels.

Products

• When treating plants with alcohol-based pesticides, usually rubbing or concentrations of methyl alcohols are used in mixed solutions. Manufactured pesticides that contain alcohols have been clinically tested, and the product includes advisories on safety and use with various plants. Follow these recommendations to avoid causing any side effects on sprayed plants. Rubbing alcohol does not have plant-specific information on its label. Various solutions are available, such as 70 percent formulations.

Potential Dangers

• Spraying alcohol onto plants may kill soft-bodied insect pests, but it may also create conditions that rupture and dry tissues. Alcohols evaporate at lower temperatures or faster rates compared to water in the same environment. Spraying alcohol on plant leaves can lower the leaves' temperatures, cooling them down rapidly. Depending on plant species, this chilling may cause damage, such as with thin-leaved tropical plants. Conversely, the evaporation of alcohol molecules from the plant tissue surfaces also creates a drying effect. On some plants, contact with alcohol leads to drying damage that looks like a brown or metallic film where tissues died from desiccation.

Recommendations

• Always follow pesticide label directions closely when applying solutions containing various alcohols. Rubbing alcohol may be sprayed on plants, but allow the solution to be at room temperature, and do not spray plants in a draft or in direct sun rays. These environmental conditions may exacerbate any cooling or drying effects on plant tissues. If uncertain of the safety of rubbing alcohol on any plant, first spray a lower, small, out-of-the-way leaf. Wait 24 hours and then evaluate to see if any negative side effects occurred. Do not use liquor or other edible alcohols on plants as they contain additives such as sugar. Residues left after alcoholic beverages dry on leaves may create a situation where mildews or insects are allured to the edible films left.