I used to think that Hoya curtisii needed full sun to form peduncles and buds.  That theory has now been completely shot down with this plant budding up in December.  This photo was taken December 14th as the day length continued to shorten; in addition, the window that it lives in is northwest with no sun penetrating at all at this time of the year.  If you despair that your curtisii has never flowered, don’t give up; it just has to get old enough, and pot-bound enough to do it.