Den goldschmidtianum and Den bullenianum cold tolerance

According to the Baker Culture sheets, D. goldschmidtianum sees mid-, to upper 60’s December through March, but D. bullenianum never sees below 70.

 

I grow goldschmidtianum with 56 F minimum nights in winter and it does well

 

I have a plant labeled Den. miyakei which is supposedly a synonym for Den. goldschmidtianum, but it stays smaller than the D. goldschmidtianums that I have seen, and is very cold tolerant (like the occasional near-freezing night on my patio) Is it really a separate species? Or just from a different, higher elevation, population? I don't know... but it is certainly more cold-tolerant than Den. goldschmidtianaum is reputed to be.

 

I am guessing you would need them to be on the drier side for those cooler nights.

 

I water everything less in the winter, and water only in the morning so things have a chance to dry somewhat by evening, but I don't give this one any particular special treatment. It's in a basket with loosely-packed sphagnum, so drying is pretty efficient, but it doesn't get as dry as a mounted plant would. If it rains (which happens occasionally, not as often as we'd like) it gets rained on. And it blooms regularly, several times a year.

I've had it for about 7 years. If its culture were more ideal it would probably get bigger - the canes typically don't get to be much more than 10 inches (25 cm), then they lose leaves and new ones come along. Flowering is only on the leafless canes. I love the compact size... no more room for big plants.