winter temp in greenhouse

[sundanz]

Fall has finally arrived in Texas! Yay!!! I put all my plants in my little greenhouse with a heater and temp gauge. The temp at night outside went down last night to 32-35, depending on where you live. So my question is this: What should be the max and or min temp be in my greenhouse? I don't want it to be too warm but I don't want them to get too cold either. The temp this morning in my greenhouse was about 50, actually a bit less, like 48-49. Is that the right temp or do I need to increase or decrease the heat? In the daytime it warms up outside to about 60 or so and of course I shut the heater off during the daytime.

Thanks for helping this neophyte! One day I'm getting this right I hope. I'm only in "this" since May and this will be my first winter with my cactus collection. ( up to 64 with 22 coming from Cactus King in Houston,)

Karin

[majcka]

It actually depends on what cacti you have in. But in general about 5C (40F) should do the trick.

[Saxicola]

Like majcka said, a lot depends on what species you have. If you have sensitive cacti you may need to keep it around 50. If your collection just needs to be kept above freezing then I'd set the temp for 40 at night. You don't want to get too close to freezing just in case your thermostat is a little off, though if you were absolutely positive your setup is very accurate temperature wise it could be set to 35.

Another factor is how much money you are willing to spend on heating the greenhouse. If you kept the temperature in the 60 degree range at night you may be able to keep a number of the plants growing throughout the winter instead of going dormant.

[vlani]

I use regular house temp controller in GH that sets to min 50 - works fine for most.cacti. Daytime can easily be 80-90 when the sun is out, plants love it.
For some epy kind like Selenicereus that is too cold actually - they tend to rot.
And for some like Pediocacti that is to hot, so they stay outside.

[sundanz]

Thanks!! I have my temp now set at 50 and when I check on my plants in the morning it's nice and warm in there. In the daytime it gets up to 80 now outside and my plants love it!

Karin

[iann]

Thanks!! I have my temp now set at 50 and when I check on my plants in the morning it's nice and warm in there. In the daytime it gets up to 80 now outside and my plants love it!

Karin

All your mesembs will be dormant

[sundanz]

So, Ian, what you're trying to tell me is that my greenhouse needs to be colder in the winter? Right now, as of today the temp at night outside the greenhouse is 61! There is nothing I can do about that.In the daytime it's over 80.My plants seem to be happy!

Karin

[iann]

So, Ian, what you're trying to tell me is that my greenhouse needs to be colder in the winter? Right now, as of today the temp at night outside the greenhouse is 61! There is nothing I can do about that.In the daytime it's over 80.My plants seem to be happy!

Karin

Depends what you're growing Winter growing mesembs probably won't even wake up. Or if they do then they will be stressed by the warm nights. Most cacti will just carry on growing. Stuff like Pediocactus will die if they never get any cold. Presumably it will get colder when winter really arrives?

[sundanz]

Ian, yes, it will definitely get colder once winter truly arrives. Sometimes we get snow albeit not too often, and then it stays only on the ground for a few days at most.So, during the winter the temp should be 40-50?

Karin

[promethean_spark]

FWIW, I don't heat my GH and it stays about 3 or 4 degrees above the outside air temp. It's been as low as 27'F in there and there were few losses (IE I lost less in plants than it would cost to heat). The few tropical C&S I have go in the garage for the winter (less than a tray).

Keep in mind plants near the walls will be colder than plants in the middle.

[daiv]

OK, sort of reviving this "old" post, but hey I have some catching up to do.

This is a good point I was going to make:

Keep in mind plants near the walls will be colder than plants in the middle.

The thermostat location is also important. If your thermostat reads 40F, that doesn't mean it is that temperature around a given plant. The situation is really exaggerated when the sun is shining.