Hi Martin, That sounds like an interesting problem. There is clearly something associated with rainfall that triggers bloom in rain lilies. I too grow my rain lilies in pots here in central Indiana. The pots spend the summers outdoors in full sun and the winters inside a greenhouse, usually dry and out of the way under a bench. Their winter treatment is very probably suboptimal to say the least. In summer, I can get markedly increased flowering of my potted rain lilies by standing the pots in saucers and keeping the saucers full of water. Even so, a natural rainfall does a better job of triggering flowering. I wish you luck in your study. I will be eager to hear what conclusions you can draw when it is finished; I'm sure others in this group will be equally interested. Best regards, Jim Shields in Westfield, Indiana -- a suburb of Indianapolis. At 12:39 PM 12/6/2008 -0600, you wrote: >My name is Martin Stone and my student, Shelton Slack, and I are working >on a research project growing _Zephyranthes grandiflora_. We are at >Western Kentucky University in Bowling Green, about an hour north of >Nashville, TN. We experience warm summers and cold winters and are >located in USDA hardiness zone 6 which means in an average winter we >will experience at least one low temperature between 0 deg F and >negative 10 deg. F. We have divided my large, old, potted clump into >smaller pots and are growing them in a greenhouse with temps no cooler >than 65 deg. F. We want to observe their flowering and try to answer >the old question about what induces flowering. They are growing well >after having been potted since September. We would like to know: > >1. Is there a period after transplanting during which flowering does >not occur? How long do we wait? >2. Is flowering sensitive to the daylength? >3. and the big question: Does anyone have clues into the nature of the >flowering? There is not much scientific literature out there and the >two main sources are a little dated and conflict. > >On a personal note, I have grown a potfull for the last dozen years from >a single corm. They are all clones of the original plant, which is a >bonus in this study. They stay outside until winter, when I bring them >into the greenhouse. But in the summer, I water my pot with the hose >every day and I see sporadic flowering. After a rain, there is a burst >of flowers a day or so afterwards. I believe the flower buds are >pre-formed and staying dormant until something about a rain event >triggers them to elongate and open. Is it temperature fluctuation >associated with a rain event? Is is cool rain water? Is it a drop in >barometric pressure (seems unlikely but who knows?). What do you think >and what are your observations? > >Thanks in Advance and I look forward to your advice and thoughts. >My Best, >Martin > >-- >Martin Stone, Ph.D. >Assistant Professor, >Leichhardt Professor of Horticulture >Department of Agriculture >Western Kentucky University >1906 College Heights Blvd. #41066 >Bowling Green, KY 42101-1066 >Office (270) 745-5963 >Fax (270) 745-5972 ************************************************* Jim Shields USDA Zone 5 Shields Gardens, Ltd. P.O. Box 92 WWW: http://www.shieldsgardens.com/ Westfield, Indiana 46074, USA Tel. ++1-317-867-3344 or toll-free 1-866-449-3344 in USA