What Are the Effects of Soapy Water on Cactus/Succulent Soil?

Every garden or plant owner should learn how to protect their succulents from pests and other environmental threats.

If you have dealt with or are currently dealing with a pest infestation on your succulent, you are probably browsing the web for solutions to kill certain insects.

One solution that is commonly vouched for is using soap water. However, some dish soaps contain chemicals that can harm your cactus or succulent.

It’s better to use horticultural insecticidal soaps designed to kill insects and cause minimal plant damage.

Using these specialized and safe soaps and other control methods, you can protect your succulent from toxic environmental damage.

While soap water is beneficial for your succulent, it’s important to buy products that don’t have additives, such as artificial color and scent.

Always dilute the product with water and avoid spraying on the edible parts of the plant.

We understand this can be difficult because some succulents are fully edible. In such cases, do not spray on the fruits and flowers.

Just like you do the Patch Test for a skincare product, spray a small amount of the soap solution on a selected leaf and wait for any reaction to check the succulent’s tolerance level.

What Happens When Soap Water Is Used on Succulents?

Your bathroom, kitchen and laundry room will give you plenty of soap options to make your DIY insect-killing spray.

However, as we said, these soaps can be toxic to your succulent. If the soap mixture is too concentrated and contains harmful chemicals, it can disintegrate the leaf’s waxy coating (cuticle) and cause dehydration.

The cuticle is the natural protective coat of your succulent that protects the plant from pests and diseases.

Too much soap water can cause the soil to remain moist, inviting gnats and leading to root rot.

On the other hand, using horticultural soaps minimize damage to the environment and plants.

However, they can also damage your succulent if overdone. Make sure you use the right amount of soap and avoid spraying your succulent for more than a month.

If the infestation and damage are too deep, you will have to take more extreme measures.

Homemade vs. Commercial Soap

According to the Colorado State University Extension, soap solutions have been used to eliminate plant insects for around 200 years.

If you read about this method of killing insects online, you probably grabbed the liquid dish soap bottle sitting beside your kitchen sink.

Some say that using a DIY solution is a better option but only if it is natural.

Commercial soaps made explicitly for this purpose are better because they don’t contain chemicals, antibacterial agents, or hand-softening lotions.

Such soaps are more likely to kill your plant and insects.


When soapy water is made with hard water, it becomes less effective. To determine if your tap water will be effective, conduct a little experiment.

Mix the insecticidal soap in a water bowl and let it sit on the counter for 15 minutes. If you see a layer of soap scum on top, the water will not give effective results.

Some soaps can be applied to the succulent but before doing this, do a patch test to ensure they don’t cause any side effects.

Why Use Soap Water on Succulents

If you see insects on your succulent, be very worried. As we said earlier, this infestation indicates that your plant is not doing well.

Whether you see spider mites underneath the leaves, aphids roaming over the plant, or gnats reproducing in the soil, you need to act fast to kill these pests, or you might not have a plant anymore.

Spraying your succulent with soap water kills harmful pests and insects, such as leafhoppers, different types of gnats, mites, whiteflies, thrips, mites, and aphids.

Pest infestation is never good for a garden. If your succulents, cacti, and other plants are planted outdoors, the insects will jump from one plant to another and infest the entire garden.

Here’s what damage insects do to your succulents:

Insects That Chew Plants: Beetles, caterpillars, and grasshoppers cause notches or holes in the foliage, causing leaf skeletonizing and defoliation.

They might even cut off the plant from absorbing any nutrients from the soil and consume the roots. Some insects create tunnels in the stem and eat the plant from the inside.

Insects That Suck Plant Sap: True bugs, leafhoppers, aphids, and scales suck plant sap and damage the succulent on a cellular level.

The feeding causes stippling foliage, spotting, misshapen or stunted fruits, and leaf curling.

Insects That Scrape the Plant Stem: Thrips scrape the succulent’s surface and flowers and suck anything that spills out from the cells.

When insects lay eggs in the soil, they cause further damage to the plant. From misshapen stems to rotten fruits, pests are the ultimate threat to succulents.

This is why insecticidal soap is recommended because they cause quite damage to insects. Moreover, it’s environmentally friendly and safe than other alternatives.

Remember, when buying any soap to kill insects, look at the ingredients list to ensure no additives harm the succulents.

Use Household Wastewater

If you use water conserved from the laundry, dishwashing, and shower, shower it on your garden plants. This dirty water is called gray water and offers certain caveats.

Do not use gray water on the edible parts of succulents. Gray water can be harmful to potted succulents placed indoors because it does not disperse harmful additives.

You can use laundry water, but ensure the detergent is free of borax and low in sodium. Do not use this gray water on the same parts of plants, as it might raise the soil’s alkalinity.

Using Soap Water

To ensure the safety and health of your succulent, there are certain precautions you need to take. Apart from the succulent’s well-being, you also need to worry about your safety.

Don’t forget to wear gloves when spraying the insecticidal soap, as direct contact with it can cause irritation.

Here’s what you need to do:

  • Dilute the Soap: Dilute the insecticidal soap according to the instructions written on the label.
  • Test it: Spray a small area of the succulent first and wait for at least three days for any adverse reactions. Once you feel confident that the spray is safe for use, you can use it all over.
  • When to Spray: It’s important to spray your succulent at the right time. When the weather is cool, and there’s a light breeze in the air, use the spray then. Avoid using it in the morning because sunlight can harm plants, and soap and water can burn the leaves.
  • Frequency: Once you spot pests on the succulent, start spraying once a week. If the infestation is severe, spray after every four days. If you don’t see any results in a month, do it for a couple more weeks. Do not spray for more than two months, or you might strip the plant’s protective oils and the waxy layer on the leaf.
  • Be Through: Cover every inch of the plant with soap and water. Don’t forget to lift the leaves and spray underneath. Since pests like to hide in dark areas, they mostly gather there.

The pests that get hit directly with the soap water will die.

The rest will stay unaffected. The hard-covered eggs will remain safe in their place, which is why they need to be sprayed on multiple times.


After you have tested the spray and covered your succulent in the soap water, look for any signs of damage.

If you see discoloration, spots, or burn marks on the leaves, spray the plant with clean water immediately.

You can gauge the effectiveness of the soap water by looking for dead insects in the soil and nearby. Soapy water kills soft-bodied pests.

It will not damage larvae or eggs. Use diatomaceous earth instead.

Make sure to search the incubation period of each insect so that you can figure out how many sprays it will take to kill them.

The infestation usually spreads within a week and can cause a lot of damage. While insects that harm succulents don’t survive for more than a week, they reproduce rapidly.

Final Word

In conclusion, DIY insect-killing sprays are less effective than commercial horticultural soaps. They don’t contain any chemicals or additives that might harm the succulent.

Take the necessary measures to keep the soil dry to avoid attracting insects. Moist soil often invites gnats to lay eggs all over the succulent.

You will immediately spot the signs, such as white fuzz and discoloration on the leaves.

The best solution is to remove the infestation with soap and water and then repot the plant to ensure no eggs are left behind.