|Primulina wentsaii in flower grown by Bill Price|
Is this the clue that we have been looking for?
From a post intercepted from Gesneriphiles by Jim Roberts:
I have not been able to flower this one after growing it for 4 years. I don't know if anyone else here has either. But I asked Avery Chen how he flowered his on Facebook. I suspected the plant might need a cool-down period. Here is his response:
"Hi Jim, I leave them outside with lowest winter temperature drops to around
4 degree these 2 years. They originate from GX with cold winter approaching freeze point. Frost could be expected. I think it might be an important triggering factor."
From my discussion of the flowering response for Primulina previously, I did not give any weight to a cold treatment. Temperature manipulation is a known technique in other commercial crops like Cineraria and Regal Geraniums to induce flowering in the Spring.
If some species are proven to be temperature sensitive, that could revolutionize predictable flowering, depending on your point of view. If Primulina wentsaii is crossed into the gene pool, there could be a line of hybrids that will predictively flower after a cold treatment allowing it to be a flowering commercial crop. The cold treatment period saves money in production. 4 degrees C is about 40 degrees F. The home owner may not be as happy if they can never get the hybrid to flower again until they learn of the cold trick.