The main thing to remember with the winter-growers is they will go dormant, probably until next growing season, if you let them dry out once. Shallow pots are very risky unless you can look at your plants every day. Oxalis tubers are annual. After they sprout and produce plants it will be a while until new tubers form. If you forget to water them and the tops die before the new tubers form they're dead for good. Many of the species have tubers that are tiny and brown. I use a mix of perlite and light-colored sand which makes it easier to see the tubers. One of the best plant propagators in the Central Arizona Cactus and Succulent Society is Joan Skirvin, who told me many Oxalis root from cuttings, either stuck in the soil or layered. I've done it with O. fabaefolia, which is one that tends to send our runners. One winter Joan took cuttings from some of my plants and she said many rooted. I highly recommend the various O. obtusa color forms. They don't make bulblets, don't reseed, are tough, and bloom a lot. If you can provide a lot of sun, try O. purpurea garnet. I would grow it even without the big pink flowers. In full sun the leaves are glowing dark red, one of the best reds I've seen in any plant leaf - rivaling or exceeding red Coleus. But if you can't give it full sun it will be a red / green and not as spectacular. O. glabra makes a great hanging basket; another way to maximize your greenhouse space. The stems are long and dangly, and it blooms a lot. Beyond those it would depend on personal taste; there are so many different leaf forms, vegetative colors, etc. I'm lucky in that I can grow them outside all winter protected only from the birds. Leo Martin Phoenix Arizona USA