Your best bet would be to contact your local extension office in the county in which you live. It's run by Rutgers Cooperative State Research, Education, and Extension Service in New Jersey. They seem to have a wealth of information at thier finger tips.

I am no expert, but I saw a sign at my local garden center that said the last frost date for New Jersey would be around May 15th. So I am not sure if that is the correct date, or they are just being safe then sorry to cover their products. Let us know what you come up with.

I always thought that the last day of frost was on or around 5/15. And we've had frosts as late as 5/25 one year (and I live but a mile from the beach in Monmouth County).

Does this mean that I shouldn't be putting any vegetable seeds in the ground yet?

If the seed has sprouted, get some 2 liter bottles and cut the bottoms off. You can cover your seedlings at night and remove the cover in the morning. I'll usually put a short stake in the ground and slip the bottletop over the seedling, and use popsicle sticks in 3's to create stability. I can post a picture if need be.

I'm a winter sower, and my tomatoes have been in containers, outdoors, for about a month now. If you've never heard of winter sowing, check out that forum here on GW. The containers I referred to are mini-greenhouses. They're just sprouting, and they'll stay protected in a container, at least at night, until mid May. During the day I keep the covers off, so they don't fry.

Bluebird. You can directly sow certain seeds such as peas, lettuce and spinach at this time of the year, but any of the other stuff should be deferred and grown in a "controlled" environment as Tracey cites in her post above.

If the volunteers I get is any indication, the pumpkins should be fine.

You could check my Frost Date Finder based on the NCDC's Freeze/Frost data...

Here is a link that might be useful: Frost Date Finder

I once planted my veggie garden on May 14th and we got a frost THAT night hard enough to stunt the growth of most of the plants. Since then, I only plant cool weather crops, lettuce, spinach, peas until AT LEAST the 15th, and sometimes I wait an extra week for my maters. Better safe then sorry.