Winter (ugh!) is coming

[majcka]

No one has yet addressed the possibility of my putting a small heater on a thermostat in there. Would that eliminate the need for layers of insulation?

Oh yes it would. And you would get enormous bill for the electricity.

[fanaticactus]

I had thought of that, Maja. But our utility bills (even electricity) are quite low here. Not at all like where I used to live (New York State, Westchester County--one of the most outrageously expensive areas in the country.)

[Saxicola]

There is no more important temperature than freezing in determining how many species you can grow. If electricity is cheap it would probably be worth your while to install a heater and set it to keep the temp just above freezing. 35 would be ideal if it doesn't dip below 32, but 40 would give you more of a safety net.

[fanaticactus]

Tonight is one of our first chilly nights. My cacti are still out (those that aren't in the GH). Inside the GH is not much warmer than outside: 54 vs. 50. I guess that's a sign that single polycarb walls don't retain a lot of daytime heat.

[Sharpy]

Also for Ralf,

Do you have a source for those connectors you are using? Or a name to search. I could see using those to help attach shade cloth to my future project.

[daiv]

Indeed, I've seen things that talk about theremal mass and having things like a rock wall/floor or barrel of water, etc, to heat up inside the greenhouse during the day, but I find that the temp in my greenhouse when the sun is not on it is barely different than the ambient temp. My greenhouse has just plastic sheet sides, but I would think that the pea gravel floor or something would radiate heat for a while. Not so!

[SnowFella]

Be similar to the difference between an inground or abovegound pool. Inground heats up slower but keeps the heat in better from the added thermal mass of concrete and ground.

[Ralf]

Ralf,
I am curious - what is the average temp inside your greenhouse in winter and what is the minimum maximum day/night temps?

Daiv, I use a propane heater so the temp inside is ~44F. The day/night temps outside are very different. So it's necessary to heat inside.

Do you have a source for those connectors you are using? Or a name to search. I could see using those to help attach shade cloth to my future project.

Doug, you'll laugh but I use the brackets also for the shade cloth during the summer. Anyway I've only one source in Germany. I don't know whether you'll get something compareable otherwhere. Click for source
They offer some different kinds of this brackets, to screw in wood or for aluminium profil (specially for greenhouses) or to glue directly with polycarbonate surfaces with a silicone glue.

Basicly if you want that the (additional) heat stay inside of a greenhouse is a insulation necessary during the winter. If you don't want to use a heater than not. Because the temp inside will be almost the same than outside, especially at night. However if you want to use a heater it is better to insulate the greenhouse. So you won't waste to much energy.
In the past I hadn't insulate the cold frames and the temps inside were only slightly different than outside. That fits only for cold hard cacti.

[*Barracuda_52*]

Ive mentioned this once befour clear solar pool cover as insulation on sunny days it will suck that right in and warm the GH up also will help keep heat in if your heating the GH. I would use it to cover the outside of the GH, for air circulation crack a vent open or use small fan. I wanted to go with the solar pool cover but cant afford it right now nor can i afford to heat my GH's all winter. Brung all my tropicals and few sensitive succulents in from the GH's there now down in the winter grow room under lights, our night time temps been way to low for them low low 30's and day temps not much better, hopefully if we get a indian summer i can take advantage of that weather and move all cacti and the rest of the succulents into the winter grow room. I saw on the news some place in Minisota already had some snow..

[Ralf]

Insulation of my greenhouse is finished.
Here you'll find the step by step post.