What Is the Ratio for Dishwashing Detergent & Water for Insect Control on Plants?

Dish washing detergent mixed with water is an effective way to kill some plant pests while avoiding the hazards of pesticides. The amount of detergent mixed into the water determines the strength and effectiveness. A higher dilution will kill more insects but could harm plants.

Dish soap can be mixed with water in different amounts to fight insects.

It's best to start with the weakest dilution and work up to higher dilutions only if necessary, to avoid damaging the plants you are trying to protect.

1-Percent Dilution

The lowest effective dilution of detergent and water is 1 percent. This will kill some soft-bodied pests but may not be as effective as the more commonly used 2-percent dilution. To achieve a mixture of approximately 1 percent, add 2 1/2 tbsp. dish washing detergent to 1 gallon of water, and mix well. For smaller batches, if you do not need an entire gallon of solution, add 2 tsp. dish soap to one quart of water, or 1 tsp. dish detergent to one pint of water.

2-Percent Dilution

A 2-percent dilution is favored by many gardeners because it is less likely to damage plants while still killing most of the intended insects. A dilution of approximately 2 percent can be created by mixing together 5 tbsp. of dish washing detergent and 1 gallon of water. For smaller batches of a 2-percent dilution, mix 4 tsp. dish detergent with 1 quart of water. Single application mixes can also be made by combining 2 tsp. dish detergent with 1 pint of water.

3-Percent Dilution

Sensitive plants, like tomatoes, are more likely to be damaged by a 3-percent dilution, so it's important to test this mix out on a single leaf or small portion of the plant prior to a full application. This stronger mix is better at killing soft-bodied arthropods, however, like the aphids that tend to attack tomato plants. To create a solution that is approximately 3 percent dish detergent, mix 8 tbsp. of dish soap with 1 gallon of water. Amounts for smaller mixtures of a 3-percent dilution are 2 tbsp. dish soap mixed with 1 quart of water, or 1 tbsp. dish soap combined with 1 pint of water.

4-Percent Dilution

The strongest recommended dilution is 4 percent. Although it is advisable to test a mixture of any strength before use, it's especially important when using the highest dilution. Even plants that aren't typically sensitive to dish soap pesticide control could react to a 4-percent dilution, especially if it's applied regularly. For a mixture that is approximately 4percent, mix 10 tbsp. of dish washing detergent with 1 gallon of water. Smaller batches can be mixed at a rate of 2 1/2 tbsp. dish detergent in 1 quart of water, or 4 tsp. dish detergent in a pint of water.

The Drip Cap

Dish washing detergent mixed with water is an effective way to kill some plant pests while avoiding the hazards of pesticides.
dish soap to one quart of water, or 1 tsp.
dish detergent to one pint of water.
A 2-percent dilution is favored by many gardeners because it is less likely to damage plants while still killing most of the intended insects.
A dilution of approximately 2 percent can be created by mixing together 5 tbsp.
Sensitive plants, like tomatoes, are more likely to be damaged by a 3-percent dilution, so it's important to test this mix out on a single leaf or small portion of the plant prior to a full application.
of dish washing detergent with 1 gallon of water.