How to Prevent Cabbage Worms Organically
on Jun 02, 2021, Updated Oct 28, 2023
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Wondering how to kill cabbage worms? Here are seven of our favorite, natural ways to deal with the very destructive, and dreaded, cabbage worm.
Welcome to the HOW TO KILL SERIES!
Who knew gardeners could take such pleasure in murdering annoying garden pests. If you garden, you’ll want to check out on the posts in this HOW TO KILL series. I’m adding new posts to this series each week, so subscribe to my newsletter if you want to know when they’re ready!
- How to Kill Cucumber Beetles
- How to Kill Potato Beetles
- Murdering Japanese Beetles
- How to Kill Squash Bugs
- Organic Pest Control for Squash Vine Borers
- Tomato Horn Worms – How to Kill!
This post, though, is all about the Cabbage Worm: how to identify, how to kill, how to prevent. So let’s get on with it!
7 Ways to Kill Cabbage Worms Using Organic Approved Methods
Cabbage worms are masters of disguise which can destroy a seedling single handedly. Or, with the help of a few siblings, they can strip the leaves off a whole crop in a day or two by burrowing into the cabbage head and eating it from the inside out.
All in all…they will ruin any hope you have of coleslaw or sauerkraut if you’re not watching for them.
They don’t just hurt cabbage. Cabbage worms also cause extensive damage to ALL brassica plants including: cabbage, broccoli, brussel sprouts, collared greens, kale, and mustard greens.
Signs that Cabbage Worms are a Problem.
There are three signs that you have cabbage worms or loopers to take care.
- Holes in your cabbages – If you start seeing holes in your cabbage plants, you should immediately suspect the cabbage worm, cabbage moth, or cabbage looper. You can kill all of them the using the methods outlined in this post. The cabbage worm and cabbage looper are the critters that do the most damage in my garden, so we’ll focus on them.
2. You see white / light green butterflies or little brown moths flying around your garden – You’ll know you have a cabbage worm problem if you start to see small light butterflies flitting about your garden. They’re kind of pretty – but as they flit around they are LAYING EGGS, and that is not good.
The butterflies are about 1 ½ inches long but can be bigger. Males will have 1 dot with a little black tip on their wings and females will have 2 dots with a heavier black tip. The females are larger.
3. You see cabbage worm poop – cabbage worm poop is a nasty greenish / brownish watery pelt type thing. You might see it around the stem or base of your plants. If you see this telltale poop – that’s another important clue that you have cabbage worms or loopers to take care of.
What do cabbage worms look like?
A Cabbage Worm is a green caterpillar with legs down its entire body. It is a solid, velvety-like green with a lighter belly. They blend in perfectly with cabbage leaves especially when they’re just little eggs.
The cabbage looper is also a little green caterpillar. It looks like an inchworm because of the way it moves. It’s missing the middle legs so it inches along your plants as it eats them. It’s pictured above.
The Cabbage White Butterfly is different from the Cabbage Moth which has a brown grey pattern on its wings wings. Its larvae are a brown green. It too is a garden pest which will eat your garden. Cabbage moth caterpillars look more like the picture above. So be on the lookout for them too.
Damage Cabbage Worms Cause
Cabbage White Butterfly doesn’t eat anything. But its larvae more than make up for it. Seedlings are easily killed in a day and multiple cabbage worms can eat holes in every single one of your cabbage leaves leaving behind a skeleton of a plant.
The larvae also poops a sweet substance called ‘honeydew’ just like aphids which gives space for a fungus called black mold. If you have cabbage worms in your garden, you need to get rid of them quickly.
How to Kill Cabbage Worms DEAD – 7 Different Ways
1. Plant the Right Companion Plants
It is possible to deter the cabbage worm altogether by picking the right companion plants to plant nearby. You want something strong scented to confuse the Cabbage White Butterfly from finding your cole and brassica crops (brussels sprouts, broccoli, cabbage etc).
Planting a row or sections of beneficial plants throughout your beds to act as nurseries for beneficial insects are also helpful. Beneficial insects include parasitic wasps, praying mantis, and green lacewing.
Companion plants that help repel cabbage worms include:
Plant these crops around your cabbages to help keep the cabbage worms away from the beginning! An ounce of prevention is worth it!
2. Plant Trap Crops
Nasturtiums seem to be cabbage worms’ favorite plant to eat. They will seek nasturtiums out to lay their eggs on and hatch into tiny worms which grow up into big green ones that strip your plants bare.
I like to transplant any cabbage worms I find that have been parasitized to my trap nasturtiums so the Parasitic Wasps will be able to help me reduce the Cabbage Worm population.
I have also grown trap crops in beds built of cinder blocks so I could set fire to them! Harsh but true. If plants are infested with bad pests before any beneficial had moved in on them. The blocks contained the fire and to be honest…it was fun to do.
3. Use Sticky Traps
Always hang sticky traps in addition to planting trap crops. Mixing crops up so the Cabbage White doesn’t have a buffet to easily mow down and companion planting crops to give beneficial bugs homes is very helpful. The companion plants mask the scent of the mustards, coles, and brassicas.
The sticky traps trap the cabbage worms. If you do nothing else, do these two things.
4. Use the Right Sprays
While we try to avoid chemical pesticides, you can control cabbage worms with a few different organic approved sprays: Neem Oil , bT, and even soapy water. The most important thing when using a spray is to spray the undersides of your leaves where eggs and worms hide. Spray your cabbage heads well also.
BT (Bacillus Thuringiensis) spray is quick to handle the issue long term as the bacteria keeps on going. An added benefit is it is nontoxic to mammals and bees. Follow the directions on your container for how to use it. You can also syringe some up and stick it directly into any spots that show where a cabbage looper has bored into your plants.
Bt WILL kill monarch caterpillars so be careful when spraying it. If you have the space you can support monarchs by creating a safe space for them far away from any overspray.
5. Use Row Covers
If you plant your cabbages in a row or in a raised garden bed, I recommend floating row covers. You can buy them or use tulle – starting when the plants go in the garden, and keep them until you pull your last cabbage out.
Be sure to have 6 inches of headspace on each side and the top of the height when full grown. You don’t want eggs laid through the tulle directly onto your veggies.
Here’s an easy way to cover your raised garden bed to protect against pests AND extend the garden season!
6. Hand Pick to Get Rid of Cabbage Worms
The most time intensive way to kill cabbage worms is to spend time looking through your garden, moving leaves, picking worms and squashing eggs while adding extra herbs in pots throughout the beds. You MUST spend this time in the garden.
7. Plant Red / Purple Cabbages
The 0 time tip is avoid green cabbages and plant only red/purple cabbages. I’ve never seen cabbage worms on my red cabbages. I believe it is because the color easily shows the caterpillars so they lack camouflage.
How to Prevent Cabbage Worms in the Future
Let’s break the cabbage worm life cycle! It is possible with a systematic approach. Since no pest makes a reservation you can only hope to stay on it and be ready to treat things when they show up.
- Never compost any pest damaged plants. Always burn them or feed them to your animals.
- I also like to encourage my birds to go through my garden when it’s put to bed looking for any chrysalis that have decided to overwinter and eat them.
- The best way to prevent them is to practice some self care and take a walk daily through your garden while wearing gloves with some pruning shears a basket for your harvest and a bucket to drown the buggers in soapy water and give the chickens a protein boost.
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Do you have any tips for killing cabbage worms? Do you use row covers to protect your cabbages through the season?