I recently finished making plans for my vegetable gardens and posted the diagrams. A reader noticed I always plant my butternut squash in one place: on the arbor in the middle of my community garden plot. I like it there. It looks nice and does well.
But the reader asked: Why don't you rotate its location?
Well my view is crop rotation is more often important for farmers growing big fields of vegetables. Growing in a small space is different. It's hard to separate plants in a 500 sq ft space. I've heard and read this, most recently from Victory Garden TV host Roger Swain at a class he gave for my Master Gardener training.
Crop rotation can be done to reduce pathogens or build soil. When thinking about pathogens, many are windbourne or spread by insects, splashing, tools, or the gardener. For these, moving crops a few feet to another bed doesn't help much. There are also crops that don't have many pests in a given area and there's no need to rotate these.
Crop rotation to build soil is a great idea even in a small garden. Squash is a heavy feeder, so I could plant a crop that doesn't like a rich soil, like carrots, in it's place the second year, and then a legume like pole beans to build up the soil the third year, and then in the fourth year go back to squash. Maybe some year I'll try this. Drawbacks are the time it takes to plan out the cycles. Also, here is a tendency for home gardeners to grow many more heavy feeding plants than light feeders or soil builders. And, it's not so hard to get a few shovelfuls of compost and enrich a small patch of soil annually. Anyway I don't rotate for soil building.
I do make sure to rotate crops that are susceptible to soil pathogens in my gardens. These include: 1. Root vegetables, 2. Tomatoes, and 3. Brassicas.
My root vegetables include carrots, parsnips, potatoes, sweet potatoes, onions, garlic, and scallions. (I haven't seen any problems without rotating celeriac and beets.) All alliums (onions, garlic, leek, scallions) need to be considered the same and none should go in the same bed without a break. I rotate them on a three year schedule. The same for tomatoes and brassicas. (My brassicas include broccoli, bok choi, cabbage, and kale.) To make it easier to rotate these, I plant each in their own bed.
Plants I don't rotate are my greens, legumes, herbs, flowers, and squashes. These don't benefit enough from rotating in my small garden. For example, my squash is prone to stem borer, downy mildew, and cucumber beetles. Moving its location won't reduce these. So I add a good pile of compost along my arbor and keep planting the butternuts there.
I'd love to hear how other gardeners handle crop rotation. I'm sure there are lot's of approaches.