Answer: A number of things can cause this. 1)bulbs could be buried too deeply. If your bulbs bloomed in previous years, this probably is not your problem. 2)ground is too wet. Again, if they have bloomed in previous years, probably not the problem. Three, bulbs are "spent" - just plain 'ole worn out, can happen after 2-7 yrs. dependent upon variety. Beds of bulbs can appear to last for decades, but that is because some varieties reproduce themselves with bulblets. I suspect one of the last two reasons to be your problem. The fourth reason is removing the foliage prematurely. After bloom, bulb foliage must be left intact until it withers and browns. It must not be removed until it dies down naturally, no matter how ugly it gets. Removing the foliage while it is still green compromises the bulbs ability to complete the photosynthetic process and this can cause the bulb to suffer greatly. The fifth reason is applying fertilizer which is too high in nitrogen (such as lawn fertilizers). This can result in a lot of green, vegetative growth, but no foliage. Keep lawn fertilizers and other fertilizers which are high in nitrogen away from blooming perennials, bulbs, and shrubs. Fertilize your bulbs with a mix designed for bulbs, like "Bulb Booster".
Hope this answers your question and provides some possibilities for the reluctance of your bulbs to bloom.
Q&A Library Searching Tips