These dates are very important to a gardener. WIthout this knowledge we have no idea where to start planning our garden. The dates are not set in stone but offer an average. Always have a plan to protect plants once they are planted. Seeds can withstand a little more cold if not sprouted in the event of an untimely frost event.
Here is a link to the USA Last Frost date chart: This is from the Farmers Almanac which is a rural planters Bible. It has dates to plant according to the moon phase also. AND NO…………. it is not about pagan rituals 🙂 Think of it like this, if the moon can control massive oceans on earth can it not also effect a tiny seed and pull it skywards a little more as well??? Sure it can. Same goes with all things in life. The moon does effect it all.
Here is another good site: Dave’s Garden which allows you to look up your zone by zip code.