Sufficiently bright light to replicate outdoor growing conditions and if greenhouse grown, cool enough temps to keep them growing, not subject to freezing, yet not too warm to encourage overly lush growth. They are easier to accomodate here in coastal California, where they grow easily outdoors, but most are also highly attractive to slugs and snails, which limits their usefulness to growing as container plants which can be more easily protected. Do you grow yours inside the house on a south/west windowsill, or in a cool greenhouse?

Those grown for the retail trade here in California are raised in temperature and light controlled greenhouses, and may possibly be treated with growth regulators as well, to keep them compact.

In a cool greenhouse, well this years blooms have come and gone and i forgot to take pictures, but the bulbs ended up in several pots and the flowers were equally impressive in all, although the smallest pot also had the smallest leaves and better over-all display and the largest pot grew plants with enormous leaves, bigger than i thought lachenalias got, single leaves 6cm x45 cm, presumably to much water and fertilizer.
What i'll do next year is grow the largest bulbs with limiting water/fertilizer for display and over-fertilize the smaller ones so they are large for the following year.