I had 6 burgundy oxalis left over from a plant exchange. Since I did not want 6 more houseplants I stuck them in the front of my perennial bed as a border. They multiplied all summer.
Before the first frost I dug them out as one would cannas. Shook off most of the soil, put them in a wide wash tub foliage and all and let them decompose. When they got slimy I dumped them into another tub so the top could dry and kept doing that till I had a mass of dried bulblets. Store them dry in the tub in a basement over the winter. In late spring
after your area frost date, spread them on the ground, pat them in, water, and they will take off. Feed over the summer as you would any flowering perennial.
Outside they look like fluttering purple butterflies.
As a houseplant oxalis growing
season is from fall to late spring
, at which time the leaves and stems will start to fall off and the plant will go dormant. The plant needs a dark spot and no water so it can rest. Then it is brought out in the fall, watered, put in the light and it grows again. Planting outside reverses the process. Right now oxalis is almost given away at nurseries that sell houseplants. I saw some in 6" pots for $1.50. Those can be divided into three or four plants. That's quite a bargin for an edging plant.