understanding when to start seedlings indoors
Not sure when last frost is and how to calculate when to start my seeds for spinach, tomatoes, peppers, and squash...will eventually move to containers outside
Delaware County Pennsylvania
There are lots of factors that affect planting time including the last frost date. This can vary from year to year. Fortunately, there is typically a window range of dates that provides some margin of safety. Here is a link from the Philadelphia Master Gardeners website that provides a table to help you understand when to plant indoors and when it is likely to be safe to plant outdoors.
This link should answer all of your questions. Good luck.