Dear Alberto and all, It is difficult to understand why in Argentina this species flowers in the summer and autumn and in a greenhouse (assuming higher temperatures) continuously from spring till autumn. While here no matter what temperatures (and even in greenhouse conditions) the first flower buds always appear the 15th of November. There is no evidence here that it is the length of the growing season which is in cause. Sometimes I destroy the growth in June to have a smaller plant and this plant also flowers from mid november onwards. Maybe we are talking about a different strain or origin. (which makes me think of an earlier discussion on the flowering time of Gladiolus daleni) We grow the cuttings of D. imperialis in an open field without protection from wind. As they are fairly closely planted they have no problem with wind. A 100 m long bed with 3-4 m high Dahlias makes quite an impressive sight . Alberto Castillo wrote: Dahlia imperialis is not a short day plant here. It is obviously a matter of temperatures as it flowers for a long period in summer and autumn. When grown in greenhouses it starts flowering in spring and does not stop until late autumn. I find a great drawback in "tree" Dahlias and it is that they can be torn to pieces by wind and it is not always easy to find a sheltered place for them in every garden. -- Lauw de Jager BULB'ARGENCE, 30300 Fourques, France Site: http://www.bulbargence.com/ "GUIDE POUR BULBES MÉDITERRANÉENS": 116 pages, 400 photos, prix 10 E Expedition des bulbes à floraison automnale est commencé. Le catalogue d'été est valable jusqu'à fin octobre Région: Provence/Camargue, Climat zone: 9a Mediterranean, dry July-August, peak rainfall in autumn, minimum temps -3-7°C (28-21F) Reference vegetation: Arbutus unedo, Olea europeaea,