Sorry, my last reply; For Summer deciduous 'bulbs' it is light levels in Winter, when they are in leaf and photosynthesising, that is important. Day and night length, as well as temperature may be important for flowering, and more hours of light will mean more hours of photosynthesising. Peter (UK) was to this: "If they aren't flowering at all or poorly, I'd definitely supplement the light, although surely more lengthly exposure to light in the summer should compensate for less intensity of light to some degree the further north you live. Can someone comment on this? Thanks, Robin" , although surely more lengthly exposure to light in the summer should >>> compensate for less intensity of light to some degree the further north >>> you >>> live. Can someone comment on this? >>> >>> Thanks, >>> >>> Robin >>> >>