flowerbug
Garden Master
Actually, what tulips we still have probably ARE coming from bulbs of bulbs by now. We gave up planting tulips years ago (the deer eat nearly all of them anyway.) but we still got two flowers last year (well, one mature flower and one tiny one I accidentally broke off while planting the pansies.)
many of the bulbs are coming back each year (they don't hold over - they reform a new bulb each year) so the thing they need is for the leaves to get enough light that they can then send back down to the roots and basal plate to reform the new bulb. if conditions were not good enough they will not have enough energy to form a flower and they will shrink, but if the next year is better then they may be able to flower again. it takes several years to take them out completely as they can restart from very tiny parts left behind. having grown tulips from seeds the initial bulb formed may be just a few mm across to start.
this is the same for crocuses and daffodils.