I’ll never forget the year I lost an entire cabbage crop to the dreaded cabbage worm.
At first, it was only a few little holes so I didn’t think anything of it. In less than a week, there was nothing left but holey nubs.
Since we garden without pesticides, I began researching natural ways to kill cabbage worms. Dish soap seemed like an easy enough solution, so I tried it.
It worked well, but one thing worked even better. (Look for a video below.)
What Are Cabbage Worms?
Cabbage worms are common pests that target plants in the cabbage family, such as broccoli, kale, and cauliflower. These small, green caterpillars blend in with the leaves, making them difficult to spot.
They can cause significant damage to your garden by chewing holes in the leaves and destroying the overall health of your plants.
These pesky creatures are the larvae of the cabbage white butterfly—a small, white butterfly with black spots on its wings.
The adult butterflies lay their tiny, yellow eggs on the undersides of the leaves, and when the eggs hatch, the larvae emerge and begin to feast on your plants.
Effects of Cabbage Worms on Plants
Cabbage worms can pose a significant threat to your plants, especially those in the Brassica family, such as cabbage, broccoli, and kale.
As these pests feed on the leaves of your plants, they weaken them, reducing their overall health and productivity.
In the early stages of infestation, you might notice small holes in the foliage. If left unchecked, the cabbage worms will continue to consume your plants’ leaves, eventually leaving only the veins and stems behind.
This extensive damage can hinder your plants’ ability to photosynthesize, which is critical for their growth and survival.
Unfortunately, the impact of cabbage worms doesn’t stop at feeding on the leaves. Their droppings, known as frass, can also contaminate your plants.
If you’re growing vegetables like cabbage or broccoli for consumption, finding frass mixed in with your harvest is not only unsightly but also unappetizing.
Monitoring your plants for the presence of cabbage worms is crucial. Early intervention can make a significant difference in containing the damage caused by these pests. Some signs of their presence include:
- Holes in the leaves of your plants
- Small green caterpillars on the leaves
- Tiny yellow eggs on the undersides of the leaves
Using Dish Soap to Control Cabbage Worms
How It Works
Dish soap is an effective way to control cabbage worms in your garden. The enzymes present in dish soap help in killing insects and bacteria, making it a safe and natural pesticide.
Once the dish soap comes in contact with cabbage worms, it only takes about 30 minutes to kill them.
Preparation and Application
To prepare a soap solution for controlling cabbage worms, follow these steps:
- Mix 1 tablespoon (15 mL) of dish soap into 1 gallon (3.8 L) of water.
- Transfer the mixture to a spray bottle.
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Once you have your soap solution ready, apply it to your cabbage plants by spritzing them liberally. Focus on the parts infested with the worms, ensuring the solution makes contact with the pests.
It’s best to apply the soap solution early in the morning or late in the evening, to avoid direct sunlight, which could cause harm to your plants.
Are There Any Disadvantages to Using Dish Soap?
While using dish soap as a pesticide is generally safe, there are a few potential downsides:
- Over application or using a concentrated solution may harm your plants. Make sure you maintain the proper dilution ratio to avoid any negative effects.
- Some dish soaps may contain harsh chemicals that could harm beneficial insects and pollinators in your garden.
- Frequent use of a dish soap solution can dry out leaves, so it’s important to monitor your plants’ health and adjust the application frequency accordingly.
Remember to be gentle with your plants, and use the dish soap solution in moderation. With proper use, it can be an effective tool in controlling cabbage worms and keeping your garden healthy.
Alternatives to Dish Soap for Cabbage Worm Control
Natural Predators
While using dish soap is an effective method against cabbage worms, there are other natural alternatives. One approach is to rely on the natural predators of cabbage worms. These predators include:
- Birds such as songbirds (and chickens, but they’ll tear up your garden)
- Insects such as ladybugs, lacewings, and parasitic wasps
To attract these predators to your garden, consider planting a variety of plants that appeal to them. For example, plant flowers like cosmos, daisies, and alyssum to attract ladybugs and lacewings.
Meanwhile, provide bird feeders and nesting materials to encourage bird visits to your garden.
Netting
Another alternative to using dish soap is utilizing netting to prevent the cabbage moth from laying eggs on your crops.
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You can cover your brassicas with lightweight netting or row covers. These materials allow sunlight and rain to reach your plants while keeping cabbage moths away.
To install the netting, use hoops or stakes to create a support structure above your plants. Drape the netting over these supports, ensuring that it reaches the ground on all sides.
How to Install Insect Netting Over Your Cabbage
Make sure to bury the edges of the netting—or secure them some other way—to prevent moths from entering underneath.
Remember to regularly check under the netting for any trapped pests and remove them.
Neem Oil
Another great option is natural insecticidal soap sprays, such as neem oil.
Applying neem oil when temperatures are below 90 °F (32 °C) can help suffocate the worms while still being pollinator-friendly.
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By following these alternative methods, you can effectively control cabbage worms in your garden without relying solely on dish soap.
How to Prevent Cabbage Worms in the First Place
Preventing cabbage worms in your garden mainly involves good garden sanitation and using natural deterrents.
First, declutter your garden at the end of each season. Remove any brassica crops, whether they appear infested or not, at the end of the season.
This helps eliminate potential areas where pests can overwinter.
During your growing season, regularly check your plants for signs of cabbage worms and remove any visible eggs and larvae.
In my humble opinion, the best form of prevention, as previously stated, is to deter cabbage moths from laying eggs on your plants by utilizing row covers.
They create an excellent barrier between the cabbage and the adult cabbage butterflies, which can prevent the worms from reaching your plants altogether.
Here are other preventive strategies:
- Rotate your crops annually to keep potential cabbage worm infestations localized.
- Monitor and control cabbage butterflies by employing decoys. These are territorial insects, and the decoys can discourage them from laying eggs on your plants.
- Don’t plant plants in the brassica family on in one spot. For instance, don’t plant broccoli next to your cabbage.
Remember to keep a close eye on your plants. Cabbage worms can be persistent and destructive, but with the right prevention methods and prompt action, you can protect your garden from these unwelcome pests.
