i have been growing a few bulbs each year in london on. i store in the cellar & then plant in pots late winter. in spring i put out in the green house til after frost then plant in garden in a morning sun spot. they only seem to grow so big after a long wait about 2 ft. i;ve not had any bloom yet it;s been 3 or 4 yrs.now. so... how am i doing ok or no ? the bulbs have enlarged though this past summer i did not have any new ones form .
To get these to grow to blooming size, you need to use a specific fertilization regime. The current year's growth is only going to be as good as the nutrition the plant received in the previous year.
What I do is to provide a broad-spectrum fertilizer with ample minor elements in the spring, switch to a 14-14-14 or similar analysis in the summer, then to a high phosphorus mix such as 14-26-6 or similar for the fall. This will induce a lot of growth in the bulb or tuber, so much so that if you have yours in a plastic pot, it may deform or break the pot!
Do this for a few years and you'll end up with a bloom!