I have been to many farms and read much and experimented on my owned. This is my general findings. I thought since it's the time of year to think about these things in the North, I'd post something.
Beware the hoop house and it's flimsy plastic. It is subject to wind, it is subject to sun. It is subject to someone with a pocket knife or box cutter, or even a fallen branch. The plastic seems like a good starter solution to get more money, but you will keep paying that fee year after year and the frame of the house supports nothing heavier.
Solid green houses are good, but beware of temp fluctuations and
water. This is also true for the hoop house, but that clear glass can quickly burn out a sensitive crop, cooking it alive. These need constant vigilance of temp and humidity.
The single plant covers or blankets are okay, if your talking mild temperature fluctuations, but they can blow away if the cold comes in a windy storm. Sometimes animals can knock them over. I think they are good for that point in spring when the temps are almost just right.
The best I've seen of structural season enhancers have been the cold frames, but as with all covered things, beware of watering. If you make it right, you can have water drain into it. The frames can be small
enough that this passive watering works. They don't vary as greatly in temperature because they are buffered by the ground, which is a really good thing. You do have to de-snow them if you get that stuff. And, things can step on them and break them.
Last, I need to mention the adapted produce. This is so totally underestimated. So many produce can handle the cold, and are even enhanced by it- like carrots, sunchokes,
rose hips. Even without protection in a place that just got single digits Fareignheit, I still have parsley, green onions, some brussel sprout greens, and some other herbs. I usually also have corn salad going too and sometimes spinach. Many other produce store very well in a cold cellar at about ground temp 50°F, such as apples. We decorate the house for fall with winter squash and dry corn. And, I grow some plants for sprouts or microgreens. Even some
mushrooms do quite well indoors. All this plant and variety choice is a whole lot cheaper than a structure.