Jim,
White are not more prolific bloomers in general... It's a plant specific as well as cultivar (variety) specific. i.e. some varieties are more prolific than others... But in general, it's just the specific plant...
re: mr ko, his nursery was devastated almost 2 years ago in a typhoon... he was selling the last of his crosses, and i presume he is rebuilding his inventory/business. I think he'll be offline for awhile..
