Answer: Forcing bulbs is a bit of a gamble on timing and results, and pre-chilled bulbs can be a bit more of a gamble, especially since there may have been unknown temperature fluctuations beyond your control. Ideally, a controlled chill (for hyacinths) would run about 12 to 15 weeks. It would start in the mid to upper 40's until roots form, then cool to about 40 degrees until there is bit of growth. (This is the part most important for shoot development.) If the growth is too tall before 12 weeks elapse, then the bulb would be held very cold (nearly freezing) to slow it down until the minimum is satisfied. Next it is brought into the light but still kept "cool" (55 - 60 degrees) for two to four weeks to bloom. So, in a nutshell, it's hard to say if you did anything wrong or if something else happened during this somewhat amazing artificial process. At least they smell good!
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