You don't mention what species/cultivar seedlings you're working with, but the regional climate of the species might give you some clue as to how much near dormancy rest period would be required. Generally, a three month rest period during which a period of no less than 400 hours at temperatures of 32'F to 36'F are obtained is most beneficial. Likewise, a gradual and most natural reduction of light, temperature and moisture is best for prompting dormancy. In the final phase, they must be brought out of dormancy gradually, reversing the process.

What is likely to happen with an abbreviated dormancy is that many of your little seedlings would not develop a stem the next spring (called a ladder), but rather come up and continue to grow just like they were before with scale leaves only. Those with ladder form would grow all season while those with scale leaves would go dormant in mid season. This presents a real problem if you grow seedlings in a pot. While those with ladders will have to be fed and watered, the others don't and they usually end up rotting.

That said, it is typical of lilium seeders like myself to extend the growing season under lights another four to six weeks and still get a sufficient three month rest period for most types. Something else we do to get baby bulbs larger faster, so to speak, is start our seeds in late January-early February. You don't say what zone you're in but if you're in a zone like Z4, Z5 or Z6, your seedlings, if started in March or April, should be more than ready to go into dormancy now. Don't worry about freezing the foliage; that won't hurt anything. A good place or way to store and provide dormancy is inside an unheated garage or by burying the pots in the garden tipped on their sides and covered with mulch once the ground freezes.

For a lot more information relevant to your questions, I encourage you visit http://allthingsplants.com/forums/view/lilies/ or by just going to www.allthingsplants.com and scrolling down to lilies in gardening section and read the 'sticky' threads on the top about 'extending the growing season under lights' and 'starting lilies from seeds'. I'm glad you're interested in growing lilies from seeds and welcome you to join in on our discussions there.

This post was edited by interspecific on Sat, Nov 23, 13 at 12:52

Thanks for your reply, Interspecific. I'll check out the other forum.