Kelly Larson says: 'We sell hardy Oxalis species that can be grown as garden plants in our Wisconsin climate, but houseplants such as Oxalis triangularis should be tucked up indoors until summer, unless you live in a warmer area where temperatures don’t dip below freezing, such as USDA climate zones 8a–11.'
After the frosts have passed, false shamrocks will enjoy a holiday outside in a sheltered, partly shaded area in your yard. Make sure they are in pots with drainage holes in the base when growing them outside to prevent waterlogging.