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.
The plastic on hoop houses can last a very long time, IF you use the right kind. The cheap plastic you can buy at the local hardware store probably won't last a year, but if you buy proper greenhouse plastic that is 6mil thick with UV stabilizers it can last 10-15 years.
We just replace the 12 year old plastic on my mom's greenhouse last year. It probably would have lasted another couple years, but a buck got into her greenhouse and tore a few holes in it with his antlers.
Cold frames are a good idea, but on a moderately warm day they can get VERY hot inside.
One of my neighbors gave me some large trays and a pump from an old hydroponics setup. The trays are about 3' x 6', enough for a dozen or so pots. I dug a hole in the ground and buried a 55 gallon barrel, put the pump inside the barrel and one of the trays on top so it drains back into the barrel, the pump runs on a timer and waters the pots. The whole thing is covered by a cold frame
I'm lazy so now I just have to refill the barrel every couple weeks. I've been thinking about adding a fan controlled by an arduino to cool it off on warm days so I don't have to pull the cold frame off.
My opinions are barely worth the paper they are written on here, but hopefully they can spark some new ideas, or at least a different train of thought
I agree with peter, proper plastic lasts a long time. I stepped up a notch and went with Solex in the roll not the rigid sheets. That stuff is awesome . Not clear but opaque , no burning on a sunny day, we do use a shade cloth during the summer months. This product even has an R value ! Warranted against uv for 10 years but I'm thinking at least 20. Free shipping on the rolls if they are around 100'. Was 7.99 Squ. ' when I bought 4-5 years ago... so ... not cheap but long lasting and incredibly durable.
I'm a big fan of our attached greenhouses. Not only do they extend my growing season right through the calendar while there's ice skating going on outside, but they heat the houses at our school. The plastic lasts at least 7 years, and lasted 11 at a friend's house. We remove ours (roll them up and tie them up under the eaves) for the summer and stretch them down for winter. Our site is horribly windy but we do pretty well with them battened on the top and sides, and dug under a trench of soil on the bottom. On a windy night they can flap noisily, and when they do go after several years, it's usually at the upper corners, apparently due to wind. The UV-stabilized plastic has been lasting just fine. We use them as patches, tarps, etc for years onward after they've been taken down.
I do agree, I like those stored winter vegetables, fermented pickles, root cellars, sprouts, dried and canned stuff. But fresh greens really make me feel better about the limited food of winter than I used to. Also I enjoy spending time in the greenery all winter, doting over the latest seedling or bloom, or lovingly pinching an aphid or two...
Works at a residential alternative high school in the Himalayas SECMOL.org . "Back home" is Cape Cod, E Coast USA.