Hello,
My name is William and this is my first post. I live just southwest of Manor, TX.. My wife and I love to attempt to grow Armenian cucumbers, tomatoes, okra, and various herbs as well as Texas Star Hibiscus, Bay Laurel, a gifted lemon tree and potted succulents. We hope to expand to include blackberries, asparagus and other vegetables we can eat and share with our neighbors and plants that feed the pollenators and butterflies. We have a 10' x 12' Harbor Freight green house which we would like to keep warm enough to keep those plants in pots alive during the months that are too cold for them to be outdoors. If anyone here has a greenhouse which they keep warm for this purpose would you share which type of heat source(s) you use?
Thank you for any responses and for allowing me to join the group.

Moving to greenhouse forum so the experts there can see this and help.

Thank you @pepper23 . My error for not searching to see if there was a Green House forum.

It's ok. Ask a Question is a good forum overall but if a forum is active for the subject matter we like to move there to get more detailed answers.

You are in zone 8b with low temperatures in the low to mid-20's?

That is correct Lucy68.

How often does it get below freezing, and how warm do you need to keep those plants? I'm experimenting with some heat sources right now up in Minnesota.

As a general rule I would say a total of three to four weeks from mid to late November to late April. The primary goal is to keep the greenhouse above 40 degrees F. My best half had thoughts of growing cucumbers and a few other vegetables but I simply cannot see that happening.

Its possible but you may have a big heating bill. I grow peppers and tomatoes in my greenhouse all winter but I also keep my greenhouse above 60 at night because I mostly grow orchids and tropicals.

I use a small milkbarn utility heater most of the time but I also have a propane Buddy Burner I can turn on for the really cold nights.

I have a remote thermometer so I can monitor the temperatures from the comfort of my living room.

Propane heater in my greenhouse for years. We don't have gas lines where we live . We rent a 500 gal propane tank it's filled up once a year to keep the greenhouse at temps to start seeds in early spring and over winter other tender plants. Zone 8b.