Mark, I have repotted oxalis at various times of year but find late January / February has been most successful. I have just repotted all my O. enneaphylla, O. adenophylla & O. laciniata. Large clumps are split up, but I like to leave at least 3-4 "bulbs" for O. enneaphylla or O. adenophylla. I grow most of my plants in 11x11x11cm mesh pots, in a sandy compost, plunged in sand in an Access frame. The sides of the frame are open most of the year, but the tops are usually closed. Plants grown in the open often go down with rust in summer for us - overhead protection seems to reduce this considerably. Hope this is helpful.