The date of the last spring frost is the important date for those seeds to survive and to be started at the earliest possible time.
The best way is to keep your own records of your garden's conditions each year. But, there are many charts to calculate frost dates based on historical data. Other factors that can influence planting dates include the soil temperature, altitude and slope of your land, any nearby waters, and day length.
The Farmers' Almanac is an old standby for this kind of information and their online tool offers you information based on your zip code.
It will tell you dates for plants with a long growing season that should be started indoors, and the seeds for plants sown in the ground. (When no dates appear in the chart, that starting method is not recommended for the particular vegetable.)
It even has information for planting by the Moon, if that's something you believe is important. By this it is meant the days when you plant. You don't have to plant at night! Above-ground crops, like tomatoes, are planted during the light of the Moon (new to full) and below-ground crops (like carrots) are planted during the dark of the Moon (from the day after it is full to the day before it is new again).
For example, there is a 50% probability that you will be frost free after April 18 according to the data from the Little Falls climate station.
There is also a page for each plant type, so a page like the one for beans includes information on planting, pests, harvest, storage etc.
A clip from their table for the Little Falls zip code:
|Crop||Start Seeds Indoors -||Moon-favorable Dates -||Start Seeds in the Ground||Moon-favorable Dates|
|Beans||Apr 18-May 2||Apr 18-25|
|Beets||Mar 28-May 9||Mar 28-Apr 9|
|Broccoli||Feb 20-Mar 6||Feb 20-25||Mar 28-Apr 4|