I know for Milwaukee (Zone 5a) that our last frost date is between March 30 - April30, but really folks when is spring go to be here. I got suckered in by the the few warm 70f days in April and did some garden work. that week I setup the rain barrels (hope they don't freeze and bust), assembled the garden beds, started some seeds indoors, and even planted a small amount of seeds outside.
I know there are 12 days before the end of April and I expected frost during some of the mornings, but not snow. Surprise snow is just another reason why a cold weather gardener should start seeds in doors. It is interesting that my onion plants, that are planted outside, are still green. Maybe they will make it. Grams says that garlic and potatoes are also 'rough tough cold weather fighters'.... maybe I should start growing some of those plants.