Hi greenhouser, I'm going to aim for a low temp of 45°, but this will be the first winter in the greenhouse so I'm learning.

I have a few caudiciform plants (Adeniums and Pachypodiums) and a few cacti (Melocactus) that might be border line at 45°, so they may winter indoors. I think the rest of mine will be fine in 40-45° (some would even go cooler.) And as you said, they should bloom better for having the cool dormant period.

I was able to get them down to high 50's by keeping them in a laundry room last winter (window slightly open, ceiling fan on, door closed) and they really responded well with better blooms! So I'm hoping they'll like the greenhouse too.
Sheri

I kept mine on the windowsills between the double pane glass the the lace curtains. It was the coolest place I could find. The taller cacti spent the winter in a dark hallway since the little HFGH was alreadu full to the brim by the frost date. Our utility (laundry) room is as warm as the rest of the house and has a door but no windows.

Hi greenhouser,
I do not let greenhouse temps drop below 50 for all my cacti & succulents. Yes "some" can take lower, but most cannot, so they all have to deal with the same temps together & yet all bloom great for me.
I try to keep it between 50 & 60...(55 being opt.) it is the safest temp for all the ones I have.

Anya 101 has a really good point! The lowest temp a succulent can survive depends a lot on which part of the world it's from, and I'm sure we all have varied assortments. My goal of 45° should work for the small group I've collected so far...but of course they may be totally different from your C&S collection, or from anya 101's.

Last fall I started marking the "hardy to" temp on the back of each plant ID marker. Doing a search on The Desert Tropicals website helps me get a rough idea of the plants hardiness (although sometimes I find conflicting info elsewhere.) It helps me learn/remember which ones are more likely to be at risk in cold temps.

Anya 101, I came across pics of your greenhouse in a thread on greenhouse flooring several months ago. Your C&S greenhouse looks wonderful!
Sheri

Thanks anya. Since the Rion will be at 60 at night the 10F difference may not matter. I can put all the cactus and succulents in the Rion rather than heat 2 GHs. I have more than enough room in it for them. Only difference then would be the humidity. It'll be higher in the Rion.