Last winter when I decided to heat my Rion 8 x 16 greenhouse I went back and forth on how to do it. I ended up with a direct vent propane heater with a thermostat. The heater rep. said that a 25K BTU would be more than enough and I disagreed. I wanted a 35K BTU. The price difference was peanuts. I used the common greenhouse BTU calculator.
I am sure glad I did.
With my lantana's, hibiscus, veggies, and recently started annual seeds, the greenhouse was warm and toasty this morning. We hit record cold of -21°. The heater has been running in this very cold New England winter coupled with the low December/January sun. This morning was its biggest test. Passed with plently to spare.
If any of you decide to heat your greenhouse, bigger is better if you live in a very cold climate like mine.
I have a fiberglass one piece greenhouse and have been doing pretty well this winter with a solar pool cover thrown over the top and bungie corded down to some rebar stakes. I still have geraniums in there with leaves on them. If the sun comes out at all during the day the temperature in there really rises. Usually 20 to 30 degrees difference even on overcast days.
I ordered the clear solar bubble wrap type pool cover. It's very heavy duty and the bubbles are large diameter. Just a bigger heavier version of bubble wrap really. The whole thing was $70 including postage and no heating bill. That said, it may not be enough for a climate that gets down to zero. The lowest we go here is into the teens, maybe a couple nights per winter. Most nights the low is in the 30's or high 20's. Teens are very rare. Good choice for zone 8 climates.
I will take it off in April, and leave it off until November, when we start to get frost again.
I never have been so excited to start seeds. This winter for us in New England has been the pits. We get 2-3 snow storms a week.
Since Christmas we have had 58". Getting rediculous. Street are all down to one lane. Roof collapses all over the news.
I will have to take a pic of the greenhouse tomorrow. My 7' Rion has fallen snow 5' deep all around it. One good thing about heating it the heat loss melts the snow so I don't have to clear it. Good for the back not so good for the wallet.
boxcar, I would love to see a picture. We were lucky, only got 4 inches of sleet yesterday topped with several inches of snow, the GH is frozen airtight so the heat is staying in, haha. My seeds all arrived today and I usually start my petunias to go out to the GH on the 14th, but I'm hesitating this year.
That's why I was curious, as I know this hasn't been a typical winter when it comes to snow and cold for most of us. Our temps have been pretty normal for us, but we have had way more snow than normal. We typically have a lot of days with sub zero temps, and always have snow and wind. Just wondering how much it will cost me when I get one built this year hopefully. Need to know how many part time jobs I have to take on so I can afford one. But, if you figure in what you would spend buying plugs and such from growers and nurseries, instead of starting everything from seed, it probably cuts that heating expense is almost half for me, as I always spend hundreds every spring on new plants, lol! And there is always the possibility of selling some of the seedlings raised in the greenhouse to help defer the cost of heating and cooling.