I found a good website for information about growing amaryllis from seed. Website of the Royal Horticultural Society/ Hippeastrum. The RHS advises to keep the young plants growing actively all winter in moderate warmth(21C or 70 degrees). You don't want to induce dormancy by dropping the temperature. You are not trying to get them to flower until the bulbs gain some size. It takes up to six years to get flowering bulbs from seeds and the offspring flower may differ from the parent flower, even if self pollinated. Propagation by offsets will produce flowers in 3-4 years and the offset flowers will be identical to the parent's flowers. Again, check out this website.
