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Quite a while back, in writing about fungus gnats and the boat farm, I promised to say something about aphids. As these things can go, my mind wandered off… However, finally, here’s the story!

Aphids are tiny insects that make their living by sipping the juice out of plants. If there are very many, the plants don’t look eaten, but they stop growing properly. Leafy vegetables develop a funny, contorted, shrunken look, and eventually they stop growing at all.

Aphids come in a number of varieties, in a size range of something like 1/16 to 1/8 inch long. Sometimes they are gray, like the ones found occasionally on organic broccoli from the store, and sometimes they are an impressive bright orange, and others look almost black. They multiply quickly once they get going, and are hard to remove by hand picking – you can get the ones that are out on the leaves, but they are quite expert at hiding in the tiny crevices of leaves and stems, maintaining enough of a population that the handpicking (at least in my experience) doesn’t do much good. For some reason, the inside-the-cabin plants haven’t developed aphids at all. That’s a blessing – aphids can be a big problem in a regular greenhouse.

In the first year of the boat farm, aphids got going on the lettuce in the cockpit, but I didn’t really understand what I was dealing with. Hoping for a little more growth, and the harvest of a few more leaves, I kept the plants, even though they were looking more and more bedraggled. Finally it dawned on me that there was no growth happening whatsoever, and the curled little remnants of leaves were not at all tasty. Over the side they went…

Last year, I had lettuce and kale going in one rectangular cockpit container. After lots of nice food from those plants, lasting for a month or maybe two, aphids started showing up on the kale. Based on the previous experience, I took that as my cue for a big harvest, and had an abundance of kale to eat for a couple of days all at once. The roots were pulled out and tossed over the side. Ordinarily, plant scraps go in the composting head, but the insect situation meant going for more drastic measures. On the idea that the lettuce did not actually look infested, I left that in the container, though I wasn’t hopeful.

As it turned out, the lettuce was fine! This was a revelation. Apparently the aphids were so fond of kale that they didn’t bother to infest the other plants, which continued on until they bolted from the heat, without any aphid problem at all. Now I’m thinking that this was a good lesson in companion planting – if you start with lettuce and kale, the inevitable aphids will come, but they will be so fond of the kale that by the time they’ve developed enough to be a problem, you will have had both quite a lot of kale to harvest AND the lettuce will be left alone.

This particular companion planting approach is a theory at this stage, but if I can get it to repeat, I’ll be delighted. Any way around, I’m satisfied with the strategy that at the first appearance of significant aphids, this means that it’s time for harvest. More food, no tending of plants that are destined to stop growing, and a sense of understanding what’s happening on the farm. I’m looking forward to the next round of trying this out, and will report findings.