Jamie, I am surprised to hear Dietes to be a winter blooming plant in conservatory in Germany. Here, I grow bicolor and grandiflora and both flower continuosuly from April now. Indeed bicolor is more fioriferous, being the stalks much branched even if flowers last just one day. Grandiflora has larger flowers, which last a couple of days (not in the hottest days) but to have a good show the plant must be large. Bicolor performs much better in partial shade, while grandiflora in sun. Anyway, they need a lot of moisture in summer and I can't overwater them. ciao Angelo