The below solutions are safe, organic methods that are easy to apply in small gardening spaces.
1. Slugs love beer. Slugs are the hipsters of the bug world and greatly appreciate a cheap beer. PBR being their beer of choice, slugs will also settle for a Corona, Budweiser or Coors Light. Take an empty shallow can (like a tuna can or cat food can) and fill is 2/3 full of beer. The slugs are attracted to the beer and will crawl in and die in the liquid. Setting up beer traps for slugs may seem cruel, but I like to think they die happily in a bath of beer. Seeing slugs drowned in beer is not for the squeamish and it is not a pretty site. If you plan to empty out the cans and reuse them I encourage you to not look at the slugs being dumped out. It is 100% gross.
2. Cabbage Worms love Collards, Kale and Cabbage even when they’re covered with Bt. Bacillus thuringiensis (Bt) is a naturally occurring bacterial disease found in soil that kills leaf eating insects including cabbage worm. Bt is sold in a concentrated formula that is diluted in water and sprayed on plants. Ensure all parts of the plant leaves are sprayed, especially the undersides of leaves where worms usually reside. Reapply once a week for 3-4 weeks until the egg cycle of the cabbage worm has stopped. If you still see cabbage worms (pictured to the right) or white cabbage moths with blacks spots (pictured above) in your garden then you need to keep retreating your vegetables. Bt degrades in sunlight and washes off in rain, so it must be continually reapplied weekly, or more frequently if there is rain. The bacteria is not harmful to beneficial insects (including honeybees), pets, wildlife and humans. You can supposedly eat the greens the same day you treat them, but I wait a few days to be safe.
3. Pull cabbage worms off plants by hand and smoosh them. This sounds horrible and disgusting, and it is. But when you come home from vacation to a garden overrun with small worms devouring your crop, you do what you have to do. This is particularly gross, so at least be sure to wear garden gloves.
4. Companion plant to deter cabbage worms. Strong scented herbs like Sage and Rosemary are a helpful companion plant for deterring cabbage worms. This solution likely won’t stop cabbage worms all together, but it doesn’t hurt. I dug up my Sage and replanted it with my Fall crops of Cabbage and Collard Greens. Another good thing about Sage and Rosemary is they are two of the heartier varieties of herbs and can usually withstand cooler temperatures in the Fall garden.
5. Build low tunnels to cover crops and keep cabbage moths from laying eggs on your vegetables. This coming week, I’ll be posting a simple method to create low tunnel row covers for your crops for four season gardening. In addition to protecting your vegetables from heavy snow and frost, row covers protect your plants from certain insect infestations. (Note: Insects like slugs that come from the soil still need to be treated. Keep beer traps under your row covers.)
I hope you find these tips helpful for your organic garden. Comment below with any questions.