At most, we had somewhat less hot weather when the first buds appeared in a few pots of Haemanthus here. So perhaps a *relative* drop in (nighttime?) temperatures might trigger things for the Western Cape and Namaqualand Haemanthus species. Given that Berkeley is on nearly the same latitude as Indianapolis, 40°N, our synchronization could be attributed simply to day length, I suppose. The UK, on the other hand, is far from our latitude so we are forced to look to other factors. I think I've read that some plants have an internal calendar that "remembers" how long it's been since they went dormant or since they last bloomed, so we can't arbitrarily eliminate long-term entrainment of the flowering and growth cycles by the environment. To answer Steve's question: my dormant pots are never watered until I see the new inflorescence starting to emerge. So, my guesses, in order from what I think most likely to least likely triggers for bloom: 1. Relative drops in daily temperatures, from hotter to somewhat less hot. 2. Long term (i.e., annual or even multi-year) entrainment of flowering cycle by climate 3. Day length changes 4. Water Incidentally, those pictures of the Haemanthus in bloom are now posted to my blog at: http://shieldsgardens.com/Blogs/Garden/… Regards, Jim Shields in cool, sunny Westfield, Indiana USA At 05:19 AM 8/27/2010 +0100, you wrote: >Winter-growing Haemanthus are also coming into flower here - buds appeared >in the dry resting pots a few days ago and are expanding rapidly now that >they are being watered. Cooler temperatures (or a sudden drop in >temperature) may be a trigger and seem more probable than daylength. We >have certainly progressed into cool 'autumnal' weather - has anyone else >noted a cooling event that could have caused flowering to start? > >John Grimshaw ************************************************* 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