Hello, I am new and in zone 7b not far from zone 8, our summers are long, humid, and hot. However, we get hard freezes and a handful of 20s nights in the winter; rarely it gets colder. During the summers I grow tomatoes and peppers in pots. I enjoy growing my own food so on a bit of an impulse I bought a Day Avocado tree and Dwarf Orinoco Banana tree. They should do well in pots outside during summer but will need warmth during winter.

My breakfast nook is south facing with 6-8 hours of sun during the winter time. It is a perfect spot, but.... I was would like to get a Bearss Lime tree, Arbequina Olive tree, and plan on trying to grow a Dragon Fruit cactus from seed. The breakfast nook isn't near big enough plus I am not a big fan of house plants and having a cat doesn't help. My options as I see them:

Turn my ratty back patio into a lean-to greenhouse; my preferred choice so I can harvest year round. The house would be approximately 12' x 18'-20'. The aluminum kits are too much but I have the skill and knowhow to design and build it myself. Before, I delve into various issues, I have one question that may be the deciding factor.

How clear is clear double wall polycarbonate?

It is hard to tell from online pictures because I suspect most of them are of the glass house options. I'd rather not obstruct the view from my living room of my cottage garden I am working to cultivate.

If I can't make the greenhouse idea work the only other viable option I have is to accept that I can't grow year round and overwinter everything in my garage. I am currently attempting to overwinter some peppers. I'll know if they make it in a few weeks but I do know it got close to freezing if not right around it, I had conflicting temps from thermometers. I can get the garage temps up by replacing the current insulated door which has serious air gaps with a new properly aligned one, My parents' garage with an insulated door stays at about 55 during the winter with temps not less than 45 on the rare, really cold nights. I can also work out some reliable supplemental heating as needed.

The big question is can the things I am interested in growing survive over winter with those temps and the light from the north facing garage door windows?

Hello Mty, some plant enthusiasts have grown ornamentals indoors by repurposing a glass display cabinet, so that soothes their need for indoor plants even in winter. It also keeps it more manageable for them. Maybe you can see the videos they made, and see if you can adapt them for your early seedlings, till your outside weather improves.
It is quite informative watching the videos, and understand the predicaments they met. Here are some I have been watching. Hope it can help you out.

https://youtu.be/BO5EM6rY1gU

https://youtu.be/PPS_Jrj5glY

https://youtu.be/2DiHPPEi7O8

If you want to use your patio as a greenhouse, you will have to use double-glaze glass. The polycarbonate will allow all the light you need through but will obscure the view. Its kind of like looking through glazed glass.

If you decide to use your garage, you will need to use grow lights - a LOT of grow lights so when you walk in, you want to put on your sunglasses.

DaisyI said:

If you want to use your patio as a greenhouse, you will have to use double-glaze glass. The polycarbonate will allow all the light you need through but will obscure the view. Its kind of like looking through glazed glass.

If you decide to use your garage, you will need to use grow lights - a LOT of grow lights so when you walk in, you want to put on your sunglasses.

That is what I was afraid of.

Are the grow lights necessary if I don't care about fruit production over the winter? The garage door has windows and apparently enough light gets in that my peppers started to leaf out at the end of December. (It was unusually warm)

If grow lights are required, out of the plants I mentioned above which, if any would not need the lights?

Thanks for the help!

Any plant that doesn't normally go dormant in winter (lose all its leaves or die back to the ground) needs to photosynthesize to survive. That means they need light or will die.

Back to building possible greenhouse I've found some aluminum windows on craigslist. They are a good size but single pane. Any reason they would be a bad choice for a greenhouse? If I did decided to build a house I'd use polycarbonate on the roof and sides of the lean-to. The side opposite of the house would have to be glass.

MTy said: They are a good size but single pane. Any reason they would be a bad choice for a greenhouse?

In one word: Heat loss (oops, 2 words)

The glass side would face the house? How far from the house walls? What direction would the glass wall face.

Where do you live? I think I remember zone 7 but do you get snow? Wind?

Please see picture below.

It would be a lean-to greenhouse so the exterior wall of the house would serve as one of the walls. Foundation of the GH would be a cement slab and house wall is brick. There is a large window and door on the house wall that would e inside the GH. Fortunately, with the current plan both the water and electrical on that wall would be inside the GH.

I am in 7b, not far from zone 8a. We get some snow/ice, not much. In a normal winter we might get 2-3 inches but it is often spread out over a storm or two or more. Our average temps for the winter season range from a low of 38 to high of 55. We do get freezes and a half dozen or so nights in the twenties on average.

My biggest concern is not heating but cooling (maybe I need to be equally concerned about both.) The glass would be south facing (which will receive more sun in winter than summer due to the shade tree having no leaves) and our summers are hot and humid with temps regularly in the 90s and heat indexes in the low to high 100s in July, August, and September. Its my understanding that single pane windows would also not help the heat because the would allow more uv through?

Wind: We can get wind. We are not a typical, constant high wind area but we do get strong thunderstorms.

Cooling involves opening all the windows and doors, running fans and spritzing the inside when it gets too hot. It will have a solid roof, won't it? That will help quite a bit.