Getting Rid of Cabbage Worms

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August is the peak month for harvesting garden vegetables. It is also peak cabbage harvesting month.

Cabbage butterflies are the number 1 enemy of plants in the cabbage family which includes cauliflower, broccoli, Brussels sprout, kale (both edible and ornamental) and—of course—cabbage.

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The bright-white butterflies (seen on the rleft) lay eggs on susceptible plants and—very shortly thereafter—voracious larvae (cabbageworm) emerge and chew large holes in the foliage.

I’ve battled cabbage butterflies for years and they are the category of insects that I find the most irritating. When I finally get my broccoli to the point where it can be harvested and eaten, I have zero tolerance for worms concealed in the crowns. Green worms and cheese sauce are a very disgusting combination!

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The solution to cabbage worm control is a weekly application of a product called BTK (Bacillus thuringiensis var. kurstaki). BTK is a bacteria that specifically targets cabbageworms and their relatives and is very safe to apply. It is best to apply BTK in the early morning or evening because the bacteria don’t like hot, dry weather during application.

Alternatively, you can use crop cover to prevent cabbage butterflies from laying their eggs altogether.

Water and sun-penetrable, crop cover is an effective and organic way to prevent pests such as cabbage worm from damaging your crop.

Brassica Oleracea

Brassica oleracea is a remarkable species. You may not know it, but members of this single species all-star team include: cabbage, cauliflower, kale and collards, kohlrabi, brussels sprouts, and broccoli.


These cool-weather loving plants are perfect for our Alberta climate. Here are a few of our favourites to grow:


Cabbage – Charmant (Brassica oleracea F1) – If you love to eat heathy (and who doesn’t?) then this is the vegetable for you! Cabbage holds the esteemed position of the vegetable that contains the least amount of fat per serving. And, as an excellent source of vitamin C and antioxidant phytonutrients, cabbage is a great defender against cancer.

Charmant Cabbage is a sweet and flavourful summer harvest cabbage. The 15-20cm dense heads are blue-green in colour, and weigh 1.5-3kg.

Cabbage is a hardy cool-season crop that does best under cool, moist conditions. It can be direct sown or grown as a transplant, with most heads being ready to harvest in 66 days.

Excellent for home-made slaws and sauerkrauts!


Cauliflower – Cheddar Hybrid (B. oleracea L. var. botrytis) – While this cauliflower doesn't actually contain any cheese, it does have 25 times the beta carotene of regular white Cauliflower, for extra nutrition in every bite!

The eye-catching orange colour intensifies when cooked, adding fantastic colour and bold flavour to any dish it’s added to. And are also great  cut raw for snack trays and salads.

Cheddar Cauliflower is just as easy to grow as its white variety, and grows from seed to plate in 5 weeks.  It prefers moist soil, lots of sun, and is great in Alberta summers since the cooling temperatures enhance the flavor of this vegetable.


Broccoli - Waltham 29 (Brassica oleracea  var.  italica) – Broccoli is one of the great treats of summer.  Known for producing large heads and long stalks, this long-time favourite is excellent for cooking fresh, frozen, raw or steamed.

The vitamin-rich head is actually a cluster of of tiny flower buds. After the head is harvested, it "sprouts" numerous smaller heads.

This cool-weather relative to cabbage is easy to grow, producing a large head filled with tightly packed florets. It grows best in mostly sunny locations during the cooler parts of the growing season, and prefers rich soil kept fairly moist.