cold enough?

[RichR]

This fall I have quite a few 2-3 month old seedlings in the greenhouse with my mature cacti. Normally I keep a heater in there and set the thermostat to 40F and everything's okay.

I'm thinking 40F may be too cold for the seedlings, but I don't know. If I set the thermostat at 50F, will the grown cacti get cold enough for a good winter rest and still bloom in the spring?

The seedlings are mostly Echinomastus, Echinocereus, Escobaria and Astrophytum.

[iann]

Are you trying to keep the seedlings growing? Is it warm during the day? The species you list would grow better at 40F than at 50F, provided the days are warm with some sun. Astrophytums maybe not so much as the others.

[Aiko]

Anything above freezing should be fine enough, especially if during the day the temperatures rises.

[RichR]

Not necessarily trying to keep the seedlings growing. I just don't want them stunted or damaged by the cold. It typically gets into the seventies and eighties during the day (in winter) as long as the sun is shining. I put up bubble wrap as a makeshift insulation and it does a pretty good job. I use a small electric heater with a thermostat so it's fairly easy to keep it at any temperature I need even during cold weather.

So if I let the greenhouse get down into the 40's on a regular basis during winter, that would allow the adult cacti to get an adequate winter rest and might actually be helpful for the seedlings?