I believe they need light and heat . Mine open if the day is warm enough, but not if it is raining and dark. Since almost all of my Oxalis are in pots, in the past in winter when the flowers weren't opening I'd bring them inside during the day if I was going to be around and they would open. So perhaps you just need to move your Oxalis versicolor inside for a few days to enjoy them. The white of the flowers can be dazzling, but the unopened flowers are just as nice. Mary Sue On 12/28/2016 4:22 PM, Diane Whitehead wrote: > Oxalis versicolor continues to flower in the greenhouse, but as usual, never opens its flowers. It's a good thing the buds show the pretty backs of the petals. I used to move the pot into a sunny spot if one occurred, but I've given up because that did not induce opening. Maybe there is a lengthy lighting requirement, or heat as well? > > Do any of your oxalis open?