Can I Spray Tomato Plants with Soapy Water?

I am sure that you have heard the myth of using soapy water on your tomato plants for preventing pests, such as aphids, thrips, or whiteflies. But is this really working, or is it a myth? Can we spray our tomato plants with soapy water without damaging them?

spray tomato plants with soapy water

Yes, you can use soapy water on your tomato plants. However, you must be careful what type of soap you are using and how do you prepare the solution. Another important aspect is to know when to use soapy water on tomato plants.

In this article, I am going to guide you on how to prepare and use soapy water to prevent damage to your tomato plants.

How to Prepare Soapy Water Spray for Tomato Plants?

Using the wrong type of soap or detergent can do more harm than good. So, it is important to know what to mix and how much to mix into the water.

Soaps and detergents can be toxic to tomato plants. A strong soapy solution that is sprayed on the tomato plants’ leaves can disintegrate the waxy coating. This can result in water loss, dehydration and makes the plant susceptible to diseases.

Therefore, it is important to use chemical-free liquid dish soap, soap bar, or liquid hand soap. Dry laundry, dish detergent, or liquid laundry soaps are too strong for this solution.

The best is to use a 1-2 percent strong soapy solution. That means you can put 1 or 2 tablespoons of the chemical-free liquid dish detergent in 1 gallon of water.

TIP: Hard water can reduce the effectiveness of the solution. If your water is rich in calcium, magnesium, or iron, it is recommended to use distilled or bottled water.

You can also add some natural scents that repel bugs. Peppermint, lavender, or eucalyptus are the best to repel pests such as flea beetles, whiteflies, aphids, thrips, fleas, flies, spider mites, and other bugs that can attack your garden.

Before spraying the tomato plant thoroughly with the solution, test the spray on a few of its leaves. You should check these leaves after 72 hours. If brown spots are present, that means, your soapy solution is not suitable for your tomato plants.

How to Apply Soapy Water on Tomato Plants?

Now that you know how to prepare suitable soapy water, it is important to know how and when to use it.

After the test spray, if there is no browning on the leaves, you can spray the whole plant with the solution. Minimize the injury by applying it early in the morning or late in the afternoon, when the sun is less intense.

The soapy water kills the pests only on contact; therefore, applying it with a spray bottle, makes it easy to spread well and ensures good coverage.

Spray the plant until it drips, making sure to spray the back of the leaves as well, where most of the pests hide.

If you want to be even more precautious against sun damage, wash the soapy water solution off your tomato plants after this dry for a few hours.

How Often Should I Spray My Tomato Plants with Soapy Water?

In order to have effectiveness, soapy water should be used once a week, for 4 weeks, or until you see improvement. This way, you prevent new pests to come to your tomato plants.

For more serious infestations, you can spray your plants every 4 days. But not more often than that and no longer than 4 weeks.

If you use soapy water for too long or too often, you risk leaf injury. The soap removes all the natural oils and waxes that protect the leaves.

How Soapy Water Works on Tomato Plant Pests?

The soapy water insecticidal solution exploits the fatty acids that are in the soap. These fatty acids suffocate small, soft-bodied insects and arthropods such as aphids, thrips, mealybugs, whiteflies, spider mites, leafhoppers, earwigs, and other crawlers.

Soapy water only works when sprayed directly on the pests. The fatty acids, when in contact with the pests, disrupt the permeability and structure of the pests’ cell membranes.

By damaging and dissolving the pests’ exoskeletons, these fatty acids are fatally dehydrating them.

As soon as the soapy water dries on the tomato plants, it has no more effect. That is why, after a few hours of spraying soapy water solution on your tomato plants, you can wash it off. Like this, you can prevent leaf damage.

Wrap Up

Soapy water can be beneficial for your tomato plants. This can repel pests, such as aphids, flea beetles, whiteflies, thrips, fleas, flies, spider mites, and other bugs.

However, you should be cautious when it comes to choosing the soap you will use for this purpose. Not all soaps are suitable. Dry laundry, dish detergent, or liquid laundry soaps are too strong for this solution.

You should always use chemical-free soap to prevent damage to your tomato plants.

You can spray your tomato plants with soapy water every week, for 4 weeks in a row, or until you see improvements.

Do not be afraid of this solution. If you are cautious and are using the right product, you can easily repel pests without damaging your tomato plants.

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