The lily should be kept small, therefore, do not fertilize. Another method is to use an aquarium. F and place a florescent grow light close to the top of the tank. Do not encourage growth. Simply keep the lily alive.
Some specialists consider starving plants in late summer, causing the formation of tubers.
Once all leaves are dead, feel under the crown for a hard tuber. Remove the tuber and wash it thoroughly. The smaller tubers generally make the nicest plants next spring. If there's any root or stem tissue still attached to the tuber, air-dry a few days and snap it off cleanly. Again, wash the tuber well and place it in a plastic bag or mason jar.