Begonia sp. U012 (AKA Symbegonia U012) is one of the Holy Grails of the exotic Begonia world. In the past, this has only rarely been available. It is considered a challenging species to grow and terrarium type culture is required.
I grow it in both an airy peat-based potting soil mix as well as straight sphagnum moss. Both work okay but i find the former easier to provide proper nutrition without the media becoming too acidic.
For me, my plants see winter nights or 60F and summer highs (under lights) of 80-85F. It does not seem overly heat sensitive but it DOES seem very sensitive to drying and shifts in growing medium PH (maybe just sensitive to shifts in general). In general, this plant seems resentful of fluctuations on wide cultural swings. Overall, this is not a beginner plant.
Offered here is a fully established and well rooted plant in a 2 1/2" - 3" pot.
The photo of it growing in a globe are just one example of how I grow it.
View Terrarium / Begonia Culture Sheet
|Int - Warm||Low - Medium|