Oxalis recommendations?

I too am an Oxalis fan and every year give offsets to the BX. I'm just
passing on the generosity of Mike Mace who shared many offsets in the
beginning from his IBS Michael Vassar collection. I still remember him
describing his delight when his wife gave him the collection as a present
and how he stayed up late planting them since they were already growing. A
lot of Oxalis enthusiasts are very generous with their extras. Bill Baird,
Uli, and Ron Vanderhoff have all shared with me too. And Diana at Telos
sells a lot of wonderful species so it isn't hard to get started (at least
in the US) and much too easy to become addicted/passionate.

I've found the winter rainfall species from South Africa do best for me if
I start watering them in August which is earlier than I start watering most
of my winter growing bulbs. This means that the early blooming species can
start flowering in September and put on a dazzling display of color during
the often sunny days we have in fall. Besides the bright colorful flowers
and the long blooming season, I also love the variety in the leaves. Oxalis
pes-caprae is the one to watch where I live where it has naturalized and
taken over in many areas of coastal California. Oxalis purpurea is likely
to spread and be hard to eradicate too for me if planted in the ground. It
also doesn't bloom for me in the shade which a lot of my property is so I
regret the few experiments where I tried it in the ground, beautiful though
it may be. However, if you have a place where you don't care if it takes
over, it is carefree and blooms for a very long time. I've tried a few
Oxalis in the ground like obtusa and they have disappeared. I've grown
others in pots in raised beds where I haven't repotted them and have had
better luck with a few species like O. flava and O. luteola, but they don't
bloom quite as long it seems as when they are repotted each year. At least
that's my experience.

Living in an area with a lot of winter rainfall and dark days, I expect my
plants will never have the tight form that plants do in South Africa and
southern California. I often grow a number of them in a cold frame where
there is sometimes just enough extra warmth to have the flowers open in
winter. Oxalis gracilis is not a strong bloomer for me and Oxalis
inaequalis was an early casualty. I did see it bloom briefly one year and
was surprised how huge the flower seemed in relation to the size of the
plants. So neither would make my favorite list although I like the color of
Oxalis gracilis.

I think my ten would have to be influenced by which was blooming at the
time so if you asked me at different times of the year I might give
different answers. But I share some of the favorites that others have
mentioned and it's difficult to choose since ones I don't have on this list
I'm very fond of:
Oxalis bowieii -- fall bloom, large bright pink flowers for a long time
Oxalis convexula -- I like the succulent leaves of this species
Oxalis elegans -- summer growing species from Ecuador from Uli, or at least
that's what we think it is, long blooming in summer, could be hardy if you
stored it appropriately since I just leave mine dormant in winter and don't
start watering until spring
Oxalis flava -- fall bloom, lots of variety in leaves and flower color,
long bloom
Oxalis hirta -- nice fall blooming plants although they need a deep pot
Oxalis peridicaria (syn. O. lobata): I too love this one from South America
with its bright yellow flowers
Oxalis luteola: I have three forms of this one, one with spotted leaves
that does not offset much. I love all three.
Oxalis obtusa: Some years some of the forms I grow bloom for three or four
months. Lots of great variety in these, but there is a pink one that
appears in a lot of pots and I wonder if it seeds itself about
Oxalis palmifrons: Grown for the leaves
Oxalis versicolor: Another favorite in bud and flower

Mary Sue