I'm so excited to say I will likely be getting a 8' x 12' greenhouse! What I have no idea about is what kind of heater I should get to extend my growing season.
Our last frost date is generally June 1st (sometimes a couple weeks sooner), but I'd love to be able to extend the growing season a bit.
I'd imagine a heater and a fan will be needed.. anything else I should be shopping for? This is all very new to me. 😊
by bumbly8ee
4 Comments
8×12 seems like a decent enough size on first impression but if you got any more room, go bigger.
A layer of poly film outside of that plastic will increase the temperature 10°F when you start heating it. Include the end walls.
I’d also recommend getting some large water tanks in there for thermal mass.
If you haven’t put it up already, zone 3 is cold enough that it would be worth thermally isolating the floor. Dig down 12-18″ (I don’t think depth matters, it’s just thermal mass so not too deep) and put a layer of foam board down, include a wall at the edge that goes up to the foundation of the greenhouse or tucks just inside of it. You can put the water tanks down at this level too, but they might require support on foam board.
Good luck!
Diesel cab heater. Use a greenhouse heat calculator (Google that term) to determine which size (BTU output) will work best for your needs and zone. You can reduce BTU demand by using rigid foam board insulation against a wall or two.
There is no cheap way to heat a greenhouse and if you plan to attempt to grow fruits and vegetables overwinter, you will also need supplemental lighting in addition to maintaining temps favorable for whatever you wish to grow. Just know that growing food in that greenhouse will make whatever, the most expensive you’ve ever put on your table.
That aside, practical use of a greenhouse is to extend growing the season on both sides by starting seeds “early” and moving established plants in before frost so as to get the last of whatever.
What is the average night time temperature where you are when you want to start to grow? If you are using 110 volt heaters you can probably keep it 30-40 degrees or so above the night temperature.
If you have access to a 220 you can do better, but you are going to start running into high cost because those green houses are designed more to heat up than to retain heat.
I have a palram greenhouse, 10×20. I am in zone 8b. I keep it to 50 degrees F during the winter and I use two of these: [https://www.amazon.com/BioGreen-Palma-Grow-Greenhouse-Heater-Digital-Thermostat/dp/B06XCJGNJK/](https://www.amazon.com/BioGreen-Palma-Grow-Greenhouse-Heater-Digital-Thermostat/dp/B06XCJGNJK/)
Make sure whatever heater you use is rated for a wet environment.