Last fall I purchased about 500 fall bulbs -- tulips, daffodils, crocus, etc., with, of course, the full intention of getting them planted. I left them in the garage, however, in the original packaging all winter. Now they are all starting to sprout. I have asked many people what to do and everyone has a different solution. In my heart, it feels like I should plant them, knowing that they won't bloom this year. (But will they bloom next spring?) If I put them in a cool dark spot, it seems they will continue to grow since they have sprouted already.
Follow your heart. Plant the bulbs as soon as possible. They will be a bit behind this spring but should still bloom since they received the necessary cold period while stored in the garage. Plant the bulbs two to three times their vertical diameter deep. Water after planting and as needed to help settle the soil and encourage root growth. Now wait for your late spring bulb display.