Home gardeners have long used homemade insecticidal soap for pest control and killing bugs on plants. Over a century ago fish-oil soap was a common solution. “Natural control” of pest is not something new in today’s green, eco-friendly world.
What Makes An Insect Soap Work
Some people believe there is a secret to mixing soap in water and spraying a plant. Somehow, this helps remove bugs. Nope! A good blast of water can wash bugs away.
The secret (if one exists) is in the “soap” used to make the pesticide soap. Use a true soap, like Castile and not a detergent or dish soap – more on recommended soaps later.
The insecticidal power – the kill – comes from the fatty acids contained in the soap.
The fatty acids work effectively on soft-bodied insects like aphids, mealybugs, spider mites, thrips and white flies. These fatty acids dissolve or remove the insects cell membranes and their natural protective waxy coatings, causing death from excess water loss.
Potassium based soaps are the most useful in making a spray to control plant pest. One of the most well-known potassium based insecticidal soap spray products is Safer’s Insecticidal Soap, which controls many pests found on houseplants, vegetables, and fruit. I like to use Neem oil for plants.
Advantages of Garden Soap
- When made and used correctly, insecticidal soap sprays are Eco-Friendly to people, plants, animals and the environment
- No residual effect
- Effective on aphids, mealybugs, spider mites, and thrips (soft-bodied insects) when coming in direct contact
- Biodegradable and nontoxic (right soap required!)
- Safe for beneficial insects, bees, etc
How To Make A Homemade Insecticidal Soap
Though there are garden soaps available to control insect pests, you can make your own effective homemade insecticidal soap inexpensively.
Dish washing detergent made for dishes may not work. The right soap is key.
The Soap – You want the real thing, pure soap which include the active ingredient of fatty acids – the bug dissolver! Try to get a liquid soap to make mixing easier.
Look for an all-natural pure soap, like Dr. Bronner’s Pure Castile Soap, found in many grocery stores or local natural-foods markets. The soap should have no synthetic chemicals, degreasers or skin moisturizers. Experienced gardeners also recommend Naphtha soap.
The Water – Use Pure Water, distilled is good. If your tap water is good use it, but if you have hard water use a bottled water instead.
The Sprayer – A clean spray bottle (1 quart) or a garden sprayer will work. It really depends on how much you need to apply. DO NOT USE a weed killer sprayer!
The Insecticidal Soap Mix:
Aim for 2% soap solution:
For a 1 Gallon Solution:
- Mix in 1 gallon of water 5 tablespoons of soap
For a 1 Quart Solution:
- Mix in 1 quart of water 1 tablespoon of soap
Soap Recipe Variations
You’ll always find variations in any homemade recipes or home-brewed formulas calling for more or less of some component.
Two consistent fundamentals in any of the various home-brewed insecticide formulas: stinky or hot tasting ingredients make the best additions.
Cayenne pepper, red pepper, garlic, powerful herbs and extracts, cider vinegar and even a cooking oil.
No “set formulas” exist, this is all trial and error. What works for one may not work for someone else.
The rates below are all for 1 gallon of spray mix:
The Bug Chaser: Garlic or Pepper – Add 1 teaspoon of garlic and/or ground red pepper.
Powdery Mildew: Vinegar – 1 Teaspoon of cider vinegar
Make Spray Stick Longer: Cooking Oil – Add two tablespoons of light cooking oil – corn, olive, grapeseed, canola, or safflower.
Learn and Observe
A Word Of Caution: Learn, Observe and Always Test!
Some spays can do some serious damage to foliage. Always do a test spray in a small area. If the spray is too strong – dilute.
Try reducing the mix rate to a 1% solution if the spray concentrate is too harsh. If you read the label, most commercial insecticidal soap sprays come in a 1% solution. However, remember a diluted solution may be easier on the plants but less effective.
While outdoors, look for plants not bothered by insects… even nearby weeds. You never know… blending some up to make some type of spray could be the new ingredient you’ve been looking for.
How To Tips On Applying Insecticidal Soap
- Before spraying make sure to test the soap solution rate – see above
- Check the weather… Don’t spray on rainy days.
- For best results apply spray early in the day before 9:00 am or late in the afternoon after 5:00 pm, this allows the spray material to be more effective by staying wet longer on the plant.
- Shake well to keep the spray solution mixed and agitated well just before applying. Keep shaking as needed. If solution sits, agitate before spraying.
- When applying a pesticide spray, remember the spray is not a residual. The soap spray must cover and wet the pest, not just put a spray drop on the foliage.
- Take the time to completely cover the tops, under sides of leaves and stems with the spray mixture.
- Give aphids, mealybugs, or mites a good complete coating, making sure they are all wet! The spray is useless once dry.
- Apply to healthy and well watered plants. Do not spray on stressed or wilted plants.
- Avoid spraying tender growth, blooming plants and plants known to be sensitive to soap sprays – ferns, waxy leaf plants, some palms, azaleas, ivy, some vegetables like tomatoes
- Repeat treatment of spray application in a week or so. Many insect problems require a followup applications depending on the severity of the infestation.