I'm sorry to say this, but I think this year I'm going to cave in. From what I've gathered talking to the local experts, the alternative is to cover it with a fine mesh net and spray with soapy water after leaving it bare for a couple weeks to make sure all the leaf eating insects go elsewhere. This leaves me with cabbage leaves that are more intact but the plants are stunted.
don't have the mesh and the bugs have already arrived. It's just a shame considering I've done so well this year without using chemical sprays. In any case I'm not going to use an aerosol and I'm going to go with the friendliest one I can find.
Pulling out the tomato plants was a lot more work than planting the little cabbage plants.
A couple of years ago, I've bought a special net to cover the plants with, so no butterflies or anything else could come close. But I never used it. Not only do I like to look at my plants (which I wouldn't be able to do when I put the net over it), but I also completely forget that I have it until I see the first couple of caterpillars. And if they are already there, the net has no use anymore - it's too late already :0)