I agree with Anne, dry in the summer and in addition I think they need to be baked in the summer. For forty years I had a 20ft x 10ft wooden greenhouse and to be honest very few flowers each year. In 2013 a willow tree fell on it and demolished it and I replaced it with two 10.5ft x 8ft aluminium ones. One containing my narcissus, plus a few frits and colchicums was in operation by late summer 2013 and last year I had many more flowers. This year virtually everything has flower spikes already and I put this down solely to the much higher temperatures I get in the new greenhouse during the summer.
'Treble Chance' (see below)is currently in flower and other pots of Jim Archibald's selections will be out soon.