Little House in the Suburbs has placed a link to a free Spring Garden Planner booklet for all of us to use and enjoy. The post link says 2009, but don’t worry, it’s good for every year. The directions for it are here.
The link they give for last frost dates are pretty vague, at least for me, so here is a link for a pdf of 90%, 50%, and 10% average frost dates for various places around the country. It’s old but the 50% at 32 degree ones are the ones I go by; it’s been pretty accurate for the last six years or so.
This is about the coolest gardening thing I’ve seen!