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The first time I experienced cabbage worms was on my kale plants. I planted them in May right after my last frost date and by June I was finding holes riddled throughout the leaves.
If you’ve had cabbage worms on curly kale before, you know the crop is pretty much done for. Finding those worms in the folds is about impossible and the idea of accidentally eating one never really appealed to me. My husband often says “it’s extra protein” and while he’s right, I just can't do it. At least not on purpose.
So I set out to find a way to prevent both imported cabbage worms and cabbage loopers. I usually end up with both on my brassica family plants(cabbage, kale, broccoli, collards, etc).
I started by covering my brassicas with row covers. This made a huge difference. But you must use the row covers correctly for prevention of cabbage worms. Here is how to use row covers for bug prevention:
Make sure the row cover has no holes. I use duct tape to repair any holes I find. If you get too many holes you may need to replace the row cover.
The row cover should be large enough that it can be pinned down to the ground. I’ve used landscape pins, rocks, pvc clips, and metal clips. My favorite are THESE metal clips.
If you row cover is blowing up in the wind or left open, it will not work. Cabbage moths or any other bug your trying to prevent will usually find the weakness and get in your row cover sanctuary.
The second piece of the puzzle was starting my brassicas very early in the spring. I start mine indoors 12 weeks before the last frost. I transplanted them in the ground under a row cover at 8 weeks before the last frost.* The do most of their development in cool weather before the cabbage moths are even flying around yet.
* Another little tip, when you are starting your plants so early in the season you will most likely get frosts. Medium weight row covers usually make the area within the row cover about 5 degrees higher than the air temperature. Anytime I expect a hard frost, I put a sheet of thick plastic over my row covers to create a greenhouse effect. Again, you must pin or weigh this down. By following these steps, I’ve never had a plant die from a frost!
The third tip is to grow varieties that mature quickly. My kale is usually ready by 2 weeks after the average last frost date for my area. It all matures at about the same rate. But the real one you need to pay attention to is the cabbage and broccoli. They have a wide range of maturity depending on the variety.
My favorites for cabbage are golden acre and red express. They make small cabbage heads compared to the longer maturing varieties, but you get perfect heads with no insect damage because you have less time for exposure to the cabbage moths and consequently, cabbage worms.
My most success has been growing in the Spring. I’m still working on perfecting the method for preventing them with fall grown brassica crops. Once I get it down I’ll share what I’ve learned with you guys!
You can prevent and get rid of cabbage worms organically and naturally. Just follow these steps.
Use row covers, prevention is KEY!
Plant early in the season
Select varieties that mature quickly
Psst… You may notice I’m not mentioning Bt (Bacillus thuringiensis) which is an organic approved pesticide that eliminates cabbage worms. Personally, I don’t like to spray my plants even with organic approved pesticides if I don’t have to. And in this case you can grow them without it!