I put a couple of plants out last year on February 28, just to say I did. They lived to produce a great crop, but they were against a south-facing wall, and required special protection about a dozen times. It's still too early to get much benefit from them being in the ground, as they may survive with care but not put on much growth. We've got a cold spell coming this week and it might be reasonable after that.

By the way, right now is peak season for "mustard weeds", which can harbor the dreaded curly top virus that kills tomatoes. Be sure to eliminate them from your property and immediate area before planting.