I grow them the same as Lilium species seedlings. I do not keep them in the pots during hot weather. I transplant them into prepared garden beds of sandy loam soil in May. I do not separate the seedlings. I plant the entire contents of the pot, and let the seedlings grow undisturbed for about one year before separating them. It helps to mulch the soil and grow companion plants, in order to keep the soil cool and control the amount of moisture in the soil around the bulbs. You should fertilize and water them all summer long. They do not need a summer dormancy. They will grow better in sun, but they cannot stand high temperatures. Above 90F (32C) the leaves exposed to sun turn brown, and the plant makes very little growth for the rest of the summer. In the shade, they make big beautiful leaves, but it takes them longer to reach bloom size. In winter, they need protection from extreme cold. The bulbs are close to the soil surface, so hard freezes will damage or kill them. They must be protected from rodents and slugs.