http://www.biologynews.net/archives/2010/12/08/plants_remember_winter_to_bloom_in_spring_with_help_of_special_molecule.html
Most plants bloom in the spring right after a cold. They must bloom then for correct pollination. Plants don't no spring from the warm. They have a since of how much cold time there's been. Plants don't literally remember because they don't have brains.

It's important to know when they bloom. So we can grow them. Crops are important to know so we can grow them. Crops are a supstancial amount of our food. It's important for the plants to no when winter is over so they can survive.