Sasha CampbellYou’ve spent weeks carefully tending to your garden, and now aphids and other sap-sucking pests have appeared on your plants. Before spending money on commercial products, try a homemade insecticidal soap spray instead.
It’s a natural way to control small, soft-bodied pests that feed on plants. When used properly, soap sprays are generally gentle, safe, and effective.
Best of all, you can feel good about avoiding harsh pesticides while still protecting your garden.
What is Insecticidal Soap?
Commercial insecticidal soaps are made from potassium salts of fatty acids. Homemade soap sprays work similarly and can help control many soft-bodied pests when used properly.
The soap disrupts the insects’ cell membranes and their protective outer coatings. This causes the insects to lose moisture quickly. As a result, they dehydrate and die.
It works on contact, so the pests must be sprayed directly for the treatment to be effective.
The good news is that it is generally low in toxicity to humans and breaks down quickly in the environment.
How Does It Work?
It works by disrupting the insect’s outer protective layer and cellular membranes. The soap breaks down the insects’ protective waxy coatings, causing them to dehydrate and die.
It works only on contact, so repeated applications may be needed. Soapy water also helps remove the scent of ant pheromones.
How to Make Natural Insecticidal Soaps
Below are three simple recipes for insecticidal soap that you can use in your garden and home.
They make effective homemade plant bug sprays. When sprayed on hard surfaces, soap sprays may also kill ants on contact and help remove scent trails. However, they are not a long-term solution for ant infestations.
Please note: soft or distilled water may work better than hard water, as hard water can reduce the effectiveness of soap.
Recipe One
To make a natural plant insecticidal soap at home, you will need a mild liquid soap, water, and vegetable oil.
Avoid harsh household detergents or degreasing dish liquids, as they can damage plants. Pure Castile soap or products specifically labeled for plants are safer choices.
Any organic cooking oil will work, such as canola, soybean, or cottonseed oil. Some gardeners avoid olive oil because heavier oils may increase the risk of leaf damage or residue buildup on foliage [1].
To make the spray:
- Mix 1 to 2 tablespoons of mild liquid soap and 1 to 2 tablespoons of vegetable oil in a small container. Shake or stir well to combine.
- Add the mixture to 1 gallon (3.79 L) of water. Shake or stir again to thoroughly mix it.
- Next, pour it into a spray bottle and label it clearly. Shake it before each use.
- Finally, thoroughly spray the leaves of your plants, especially the undersides.
This DIY insecticide is a safe, natural option for controlling many common soft-bodied garden pests. But be sure to spot-test a few leaves first to check for any damage before spraying the entire plant.
Recipe Two
For this recipe, you will need just two ingredients:
- 2 to 3 tablespoons of mild liquid soap (some people use Dawn dish soap, but we prefer not to).
- 1 gallon (3.79 L) of water
Mix the soap and water thoroughly in a spray bottle or pump sprayer. Shake before each use to combine.
That’s it! This DIY insecticidal soap helps control soft-bodied insects and other pests. It works against aphids, spider mites, mealybugs, and whiteflies.
It’s also a mild liquid soap spray for your plants. However, test it on a leaf first to check for leaf burn (some plants are very delicate); then spray your plants thoroughly.
This gentle spray can be used on both indoor houseplants and outdoor garden plants.
Recipe Three
This one has Castile soap, neem oil, and water.
To make a DIY insecticide, mix 1 tablespoon of neem oil with 1 tablespoon of organic Castile soap in 1 liter of water.
Dr. Bronner’s liquid Castile soap is a good brand. The Castile soap helps the neem oil mix evenly with the water.
Shake well, then apply it to your plants as in the other recipes. However, test on a small section of the plant first, as neem oil mixtures can damage sensitive plants.
How to Use Soap Sprays
Once your insecticidal soap spray is mixed, it’s time to use it. Apply it when insects or their damage are first noticed.
For optimal results, spray plants in the evening or on overcast days when the sun’s intensity is reduced. Avoid spraying during hot, sunny conditions because soap and oil residues can increase the risk of leaf burn or plant damage.
Spray the pests directly. Also, thoroughly coat the tops, undersides, and stems of the leaves.
Additionally, pay close attention to areas where you see insects or insect damage. Spray until all surfaces are evenly coated, especially the undersides of leaves.
This solution targets mature insects, larvae, and nymphs, but is generally ineffective against insect eggs. However, some delicate plants may be sensitive to soap sprays, so always test a small area first.
How Often to Use
To keep pest populations under control, apply homemade insecticidal soap when pests are first noticed.
During active infestations, reapply every 4–7 days until pest numbers decline. Continue monitoring plants and spray again if pests return.
Types of Insects and Related Pests That Insecticidal Soap Controls
Insecticidal soap spray controls several common plant pests [2]. The soap solution is most effective against:
- Aphids
- Certain sawfly larvae, particularly rose slugs and pear slugs.
- Mealybugs
- Mites (spider mites, broad mites, rust mites, etc.)
- Young scale insects (crawler stage)
- Leafhoppers
- Whiteflies
- Psyllids
- Thrips
- Ants (short-term contact control only)
Aphids are one of the easiest pests to control with insecticidal soap. Their soft bodies and habit of clustering on stems and the undersides of leaves make them especially vulnerable.
Plants Sensitive to Soap Sprays
Some plants are more sensitive to soap sprays, including certain ferns, succulents, begonias, Japanese maples, and newly transplanted plants.
Always test the spray on a few leaves and wait 24–48 hours before treating the entire plant.
Best Ready-Made Insecticidal Soaps
If you prefer not to make insecticidal soap, you can purchase popular options trusted by many gardeners.
Below are two good options:
Bonide Brand
This ready-to-use insecticidal soap can be applied indoors and outdoors to kill insects on contact. It is powered only by potassium fatty acids (derived from plants).
Bonide Insecticidal RTU Soap also breaks down quickly in the environment. You can apply it regularly as directed on the label.
You can also apply it to edible plants up until harvest day.
Monterey Brand
Monterey Insecticidal Soap is an all-natural product. It acts as both an insecticide and a fungicide.
This soap spray helps control common pests and diseases in your garden. It works on contact, so spray when insects are most active for the best results.
It also helps to prevent and control powdery mildew.
Takeaway
These insecticidal soap spray recipes can help you combat common garden pests without using harsh chemicals.
The best part is that you can feel confident knowing what is in the spray and that it is generally safer for the environment, kids, and pets than many synthetic pesticides when used properly. So grab your spray bottle and get mixing; your garden will thank you.
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