Newby question Season Extender vs Greenhouse

I'm trying to graduate into a longer growing season but I'm confused about what structure to invest time and money into. My main question is the functional differences. The way I understand it you'd build a hoop house to keep the frost off young plants in the early spring and keep a bit more heat into the fall. However you can keep it from freezing you can grow all year long. Is the keeping the temperature regulated (above freezing or where a particular crop needs it to be) the goal for year round growth vs season extension?

Thanks for your time and any advise you can pass to a newb!
Bert

Heating a greenhouse is way too expensive for my lifestyle, so I use it only as a season extender.

The main purpose of my greenhouse is to be able to grow transplants of warm weather crops like tomatoes, and to get an earlier start on cold weather crops like Fava beans that really don't like my summer heat and low humidity.

I start my tomatoes about 6 weeks before our last frost date... During that time, I might need to heat the greenhouse for two or three nights, just enough to keep the plants from freezing.

I can plant tomatoes directly into the greenhouse months earlier than outside, if I cover them with cloches, and put bottles of water around them, and cover them with a floating row cover or two. I don't have to heat that arrangement, and can have fruit about the same time that I am ready to transplant seedlings into the field.

Even without providing any heat, I can grow cool weather crops like spinach, lettuce, onions, chard, etc. Harvests of these crops can be ready before the corresponding crops are direct seeded into the field.

This year I grew sweet potatoes in the greenhouse: Primarily for the added humidity and extra summer heat. They will also get a month or so of extra growing season in the fall. They didn't even get planted until after my tomatoes and peppers were put into the field.

Heating a greenhouse is EXPENSIVE! Not a good use of resources on a large scale unless you have a serious cash crop to cover the bill. A small greenhouse for starts and kitchen garden may be worth it to you, however.

Low tunnels, row covers, cloches, cold frames--they all have places and uses depending on your climate and crops.

Go to YouTube and search for Eliot Coleman. He goes over all the systems in an hour, hour and a half video. I can't search for it from my phone right now, but will add it later if I remember.

Thanks much for the replies, seems like I probably have my answer. Here in Central Oklahoma our Spring and Autumn are fairly mild but several periods of below freezing for many days in the Winter.

R Scott I will be checking out that video.

I forgot the best part about a greenhouse: Being able to have a place to go that is out of the wind, rain, and snow. Where there might be the possibility of playing in the dirt or enjoying a sunny day...