How To Use Castile Soap For Aphids

Gardening is a wonderful and productive hobby. But it can be frustrating to watch the fruits of your labor get destroyed by aphid pests.

When pests start feeding, could you reach for castile soap instead of chemical sprays?

Pure Castile soap spray are one of the basics in a homemade insecticidal soap sprayPin
Dr. Bonner Pure Castile soap spray is a basic insecticidal soap spray | PlantCareToday

On the one hand, no one wants pests ruining their plants. On the other hand, you don’t want to damage crops or make them inedible.

Thankfully, there are natural options available without turning to harsh chemical solutions. Many botanical gardens and horticulturists recommend using castile soap for plants and aphids. Before you ask – “Does Castile soap Kill Aphids?” Yes, it does!

Before trying soap sprays yourself, gather all the information you need. Soaps have been used to control insect pests for more than 200 years. We always mix soap-detergent sprays with water when we use them. Usually, the mix has about 2% to 3% percent soap, and the rest is water. [colostate.edu]



What Are Aphids?

The aphid pest is a small, soft-bodied insect that sucks sap and plant juices. It is a common garden pest that reproduces many times a year.

It is essential to keep an eye out for them regardless of the growing season. They are smaller than an eighth of an inch. Aphids may be difficult to see unless they cluster together on the underside of the leaves or stems.

Female aphids also commonly lay hundreds of eggs that hatch the next spring.

Aphids damage a variety of plants, including shrubs, vegetables, perennials, annuals, and trees. They typically target stems, buds, and fruit.

In short, aphids go after softer new growth instead of more established foliage. The old leaves are tougher. Keep an eye on any fresh blossoms and buds on your plants. The new growth is where to focus any insecticide spray when you spot aphids.

What Damage Can Aphids Do?

Aphids suck sap and juices from plant stems, leaves, and new growth.

The damage causes plant leaves to turn yellow or brown and wither. Over time, aphids will weaken a plant, causing it to stop flourishing or making it grow in a deformed manner.

The Chicago Botanic Gardens also warns about “honeydew,” a sweet substance aphids excrete. Since honeydew is so sweet, it causes black mold to grow on leaves.

The black mold fungus does not usually harm the plant. But it can cause issues. If the mold covers the leaves, the plant might struggle to make food from sunlight, a process we call photosynthesis.

How To Control Aphids

Knock aphids off plants with a forceful water spray. Try spraying the plants in the morning or when you typically water your plants.

Spraying in the morning can free plants of aphids. It also allows the sun to burn off any insecticide you apply.

If aphids cover a plant stem completely, some gardeners prune the whole branch off. Pruning is their attempt to get rid of the aphids without risking the entire plant.

Some insects feed on aphids, like ladybugs or lacewings. These beneficial bugs can be purchased for use in the garden.

Some growers use pesticides that can be very harsh. Castile soap insecticide spray is a preferred natural alternative. Before you ask – “Does Castile soap Kill Aphids?” Yes, it does!

A succulent plant in a red pot next to a bottle of Dr. Bronner's rose-scented castile soap on a wooden surface.Pin
Photo Credit: Instagram @simplygreengr

NOTE: Years ago, I worked at an orchid nursery. At the nursery, I learned that using Castile soap aphids can be managed effectively.

Aphid Castile Soap Solution As A Natural Insecticide

Since aphids have soft bodies, you don’t need to use anything harsh to permeate their tough exteriors.

A soft bodied insect is excellent news for pest control. Applying Castile soap for aphids allows you to get rid of bugs and mealybugs, flea beetles, tomato caterpillars, thrips, and whiteflies without harming your plants!

Dawn liquid dish soap and castile soap are gentler than regular dish detergents. Many soaps are harsh enough to clean food off of dishes.

Castile soap is affordable for making small or large batches of natural insecticidal soap spray.

For a small batch of castile soap insecticide recipe:

  • 1 tablespoon of castile soap
  • 1 quart of warm water

For a large batch mix:

  • 5 tablespoons of castile soap
  • 1 gallon of water

Once it’s mixed, don’t forget to screw on the lid of the garden sprayer and shake the container thoroughly.

Adding vegetable oil helps the spray stick to the leaves and the aphids.

Use half a tablespoon of cooking oil in the small batch or two tablespoons in the large batch.

A hand holding a bottle of Dr. Bronner's soap next to a book titled "Honor Thy Label" with the same branding.Pin
Photo Credit: Instagram @drbronner

Keep the homemade insecticidal soap mixture in a labeled spray bottle. You need to reapply it to plants every few days.

Only spray plants when you see aphids clustering on leaves or on new growth. The liquid soap contains the fatty acids.

These acids damage the outer membrane of soft-bodied insects. With the membrane gone, the pests become dehydrated and die.

You can also use a mixture of peppermint castile soap and neem oil for pests, especially spider mites, in your garden. Adding cayenne pepper powder to the mixture will also repel a broad range of pests.

Use Castile Soap Aphid Spray Carefully

It is best to use castile liquid soap on aphid infestation when plants are no longer in direct sunlight at the end of the day.

Some botanical gardens say the soap will dry out before it is useful. Others claim that the sun causes the soap to burn and damage the plants’ new growth.

Castile soap bottle with spray nozzlePin

Spray the castile soap solution for aphids clusters directly. Beware, the mild liquid soap mixture also harms:

  • Other beneficial insects and their larvae
  • Honey bees
  • Ladybugs

Any remaining residue on the plants will not harm humans if you spray crops you can eat. When protecting your plants from harmful insects, use Castille soap for aphids as a reliable solution.

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