If the plant hasn’t bloomed in 12 years, it may be impossible to get it to do so, but we’d certainly try. Keep the plant cool; it likes temperatures around 45 degrees Fahrenheit. Water it sparingly, and don’t worry about fertilizer. Clivias like to be root-bound, so repot it only when absolutely necessary. Should you get the plant to flower (which will occur toward the beginning of summer), place it outside, where it can enjoy the sunshine and heat (water it well), then bring it back inside in the fall and follow the low-water, cool-temperature routine. If you’d like to experiment, try dividing the plant. We don’t know if this will help it flower, but it’s worth a shot. Read more about caring for clivias.