In the winter mine are fully exposed to the sky and full Phoenix sun, and not protected from cold. I keep them moist to wet during the winter. They routinely experience winter daytime temperatures between 40-80 F / 3-25C and overnight frosts to the upper 20s F / maybe -4C and have several times been completely undamaged with overnight frost down to the mid teens F / -8C. Note that it always warms up above freezing here when the sun rises. I might add that Massonia leaves are frozen solid like popsicles by this treatment but thaw undamaged. So if you have another place for them with winter sun that doesn't get too much cooler than this, you don't need to take up precious heated greenhouse space with this plant. In the spring both V. species go dormant when it heats up. I have left the containers outside in the shade where they get some summer rain. I have also brought them into the house for the summer. It seems not to matter to them. My plants aren't big enough to bloom yet but they do grow well. Blooming now: Oxalis callosa, flava, hirta, pocockiae. My Oxalis suffered a severe puppy attack while dormant and I don't know what is going to come back this season. Leo Martin Phoenix Arizona USA