I wonder. At its natural habitats in the Sierras de Cazorla/Segura/Villas
(Spain) P. vallisneriifolia is dormant now and the winter buds last for at
least 4 months (october/november till february/march). The new rosettes
begin to develop not before the first week of march. If you have 'growing'
specimens of this species now it is likely that their next winter buds
will be formed already in august, followed by vernalization in
december/january. The vernalized rosettes usually do not survive. The
winter buds are frost resistant and like temperatures of 0-5 Celsius. Keep
the rosettes now as cool as possible (between 5 and 10 Celsius) till march.
I grow this species for over 25 years now and was not successful when I
deviated from the natural day lenght/temperature cycle.
Merry Christmas and happy New Year to all! Juerg
___________________________________________________
Dr. Juerg Steiger, Institut fuer Aus-, Weiter- und Fortbildung IAWF
University of Bern, Inselspital 37a, CH-3010 Bern, Switzerland
Office: +41 (0)31 632 98 87, Home: +41 (0)31 972 19 79
Fax: +41 (0)31 632 98 71, E-mail: steiger@iae.unibe.ch
Web: http://www.iawf.unibe.ch/index.htp