This is classic behaviour for true bulbs which require a dormant phase with temperature fluctuations to initiate the flower bud before shoot growth. (It is the shoot growth behaviour which is adjusted in chilling tulip bulbs through the summer). I was talking to Tony Hall (ex Kew) a few years ago, asking him about tropical and Summer growing bulbs in this respect. As I remember it, he thought that the temperature fluctuations could be quite small for some species, the dormancy quite short, and that the amount of temperature swing was more critical than any specific temperature reached. As I understand it, Summer growing bulbs need a relatively cold period at the onset of the dormant phase and Winter growers need a relatively hot hot period of time. Peter (UK) On Fri, Nov 22, 2013 at 11:49 PM, J.E. Shields <jshields@indy.net> wrote: > > I have also found that a brief dormant rest period is very helpful in > getting bloom. Charles drives his bulbs into a dry rest period each summer > when the greenhouses get their hottest. When he resumes watering, the > blooms follow. > > I usually dry my bulbs off in winter, and water heavily right through the > heat of summer. I seem to get a reasonable amount of bloom from my > presently very limited collection. I suspect that the rest period is > crucial, as is the mass of roots to support the bulb and its flower. The > precise time of the rest may not be; but if you are not getting bloom, try > varying the time of year when you give your rainlily bulbs a rest. > >