I have been reading up on greenhouses and have discovered that most people plant veggies and fruits in a green house using mono-cropping thinking. Do any of you who use greenhouses (4 season) do things like companion planting? square foot gardening? etc?
Sure....the permaculture triad of flower/herb/vegetable works particularly well in a greenhouse because you also need to lure in pollinators. I do tomatoes as the vegetable because where I am summers are too cool, near the ocean, to get good crops of tomatoes. But I always get even better crops when there are flowers. In the case of tomatoes, the flowers have to be open in March/April when the tomato flowers start, for the earliest pollination. The greenhouse has early blooming rosemary on both ends, that are not enclosed with panels, just chicken wire and shade cloth if the wind needs to be blocked.
Some of the cherry tomatoes act like perennials, and overwinter (in my mild winter area) so they are blooming in March. I always start my own tomatoes from seed inside with a light table in December, so they are often blooming by the end of March.
Also hugelkultur trenches during the winter, so the planting is easy come spring. The trenches turn into hot piles that keep the heat up in spring. I haven't had any issues with the soil by monocropping there, I think because of the hugelkulture input.
I don't put perennials in the greenhouse because I can alternate where I put the tomatoes/peppers, moving them over about a foot one year, then moving them back the next. It also gives me more room to move around in a confined space and its easier on the back.
The only issue I have in the greenhouse is when the packrats and voles get in, and are protected, and eat the tomato plants. That's an ongoing thing.