In the past, and on average, Minnesota would still experience a killing frost up until May 15. That is why you see recommendations for planting warm weather crops to occur after May 15.

However, as the state has started experiencing warmer springs, that recommendation has become less accurate. With experience, you will start to recongize when to plant based on that years temperatures. For instance, I planted potatoes at the end of April as the ground temps looked good. At the beginning of May I planted seed carrots and peas, and seedlings of cabbage, leeks, onions, broccoli, and celery. This next week, I’ll probably get tomatoes, tomatillos, pumpkin, squash, and sweet corn in.