Hi Joe,

Heat and bright light are the enemies to stalk elongation. Anything you cna do to keep the plant cool and in the dark will help. Some use super phos fertilizer as well. Late blooms often times get stuck in the crown. Just the price we pay for a summer Clivia bloom. Good luck,
Craig
Sacramento, CA

I meant to thank you Craig. I reduced the light (couldn't do anything about the heat, but it was in Nova Scotia so that didn't really matter much) and voila! a nice long (and very thick) stalk. The flowers didn't open all at once, so I only got a few berries, but still nice. Thanks