It’s a common misconception that dish soap will kill all plant life. In reality, dish soaps are relatively safe to use around plants and garden beds as long as you follow a few simple guidelines.
Dish soaps have been used for decades by homeowners who want to control pests in their gardens without using harsh chemicals.
Diluted dish soap is also great for irrigating flowerbeds during dry spells when other water sources may be scarce or unavailable.
The best dish soap spray should contain only 1-2 teaspoons of dish soap per gallon of water–too much can cause damage to the leaves on your plants.
Types of Soapy Water
The chemical composition of soapy water varies considerably depending on the type of soap used.
Because it’s developed especially to control pests and minimize plant damage, commercially produced insecticidal soap is the best option.
Liquid hand soaps and dish detergents for hand-washing dishes, not the kind that is used in dishwashers, are also efficient and, of course, less expensive. Additives, fragrances, dyes, and moisturizers may all be harmful to specific plants.
Before utilizing these regular soaps on your plants, test a small amount of the solution on one plant and wait a few days to see if any damage has been done.
Water from Your Home for Reuse
You can irrigate your garden with gray water, which is water saved from your shower, hand dishwashing, and laundry — also known as gray water. Gray water might contain germs. It should not be kept for longer than 24 hours and should be kept at a distance from food crops’ edible surfaces.
Only use laundry water if your detergent is liquid, low in sodium, and devoid of borax; rotate where you use it to prevent soil alkalinity from increasing; and limit the amount used in one area because frequent usage in the same location may cause soil acidity to rise.
How Does Insecticidal Soap Spray Work?
Insecticidal soap spray, which is less toxic than traditional insecticides, is useful against soft-bodied pests like aphids, spider mites, scales, thrips and mealybugs. The waxy outer layer of insects with a hard coating, such as wasps, flies, beetles and other insects that it doesn’t kill effectively.
If you see honeybees or lady beetles on plant leaves while using insecticidal soap, don’t worry. These beneficial insects are not harmed by the soap solution.
Soapy water will kill most of the pests on contact, and it also works as a residual spray to control pests that come into contact with the leaves later. The fatty acids in dish soaps dissolve the waxy outer layer of insect cells, which causes them to die.
When Can I Use Insecticidal Soap Spray?
Insecticidal soap is usually most effective when applied using a spray bottle early in the morning or late in the evening when temperatures are below 85 degrees F. Spraying during the heat of the day can cause plants to sunburn.
How Should I Dilute Dish Soap for Garden Use?
You should dilute dish soap with an equal amount of water and spray the mixture onto plant leaves until they are soaked. Dish soap with high-fat content, such as Dawn dishwashing liquid, is most effective for controlling garden pests.
Is Insecticidal Soap Safe to Use Around Plants?
Dish soaps that contain nonylphenol ethoxylated (NPE) or linear alkyl sulfonates (LAS) may be harmful to plants because these chemicals can build up in the soil over time.
Fortunately, newer dish soaps like Dawn dish soap don’t use these chemicals anymore and instead rely on different ingredients like potassium salts of fatty acids and sodium salts of fatty acids–both natural substances found in coconut oil.
These modern dish soaps should not harm your plants if used according to the manufacturer’s instructions.
Always test a small area of your plant before spraying the entire plant to make sure there is no adverse reaction. Some plants, such as tomatoes and peppers, may be sensitive to dish soap and show signs of distress after being sprayed. If this occurs, discontinue the use of dish soap on these plants.
Be sure to read the label on your dish soap bottle before using it in your garden–not all dish soaps are safe for plants. Follow the guidelines listed above to ensure that you’re using dish soap safely around your plants without causing any damage.
Using Dishwater for Plants
In addition to dish soaps, homeowners can also recycle dishwater by using it to irrigate plants. Most of the detergents and chemicals in dishwater are biodegradable and will not harm plants. If you don’t have a garden hose, you can use a bucket or watering can to pour the dishwater over the plants’ leaves.
Dishwashing water is especially beneficial for plants that need extra nitrogen, like tomatoes, lettuce, and cucumbers. Be sure to dilute the dishwashing water with an equal amount of clean water before using it on your plants to avoid any damage.
Recycling dishwater is a great way to conserve precious resources while helping your garden thrive. Follow the guidelines listed above for safe dishwashing water use in your garden.
How Often Should I Spray Plants with Soapy Water?
You should not need to spray your plants with soapy water more than once a week. If you find that aphids or other pests are returning after spraying, then you may need to increase the frequency of your sprays.
Be sure to test a small area of your plant before spraying the entire plant to make sure there is no adverse reaction. Some plants, such as tomatoes and peppers, may be sensitive to dish soap and show signs of distress after being sprayed. If this occurs, discontinue the use of dish soap on these plants.
Spraying Soapy Water to Control Weeds
Soap doesn’t care. It will destroy plants equally as well as those you do want. To make a herbicide that will work in your weeds without harming the environment, combine 5 tablespoons of dishwashing liquid or liquid hand soap with a quart of water. Coating weeds thoroughly and promptly causes them to wilt. When it’s hot outside, this technique works best since plants are most vulnerable to dehydration.
Gardeners often make homemade insecticidal sprays from dish soap and water, and the spray helps to control a number of common garden pests. Some environmentally conscious homeowners recycle dishwater by using it to irrigate flowerbeds.
Usually, small amounts of well-diluted dish soap don’t hurt flowerbeds, and soapy water is better than no water for plants during a drought.
Don’t assume that dish soap is completely safe however–it must be applied according to certain guidelines in order to prevent plant damage.
Always test a small area of your plant before spraying the entire plant just in case there’s an adverse reaction–some species may be sensitive to dish soap and show signs of distress after being sprayed with this substance.