The first year that I planted a garden here in Shelby, Corinne Merhar warned me not to put out the tomato plants before Memorial Day. I had to learn the hard way. You're not "safe" from frost in Shelby until the end of May. A few years later I had the biggest most beautiful tomato plants I had ever grown....until a freak August snowstorm blew through.
Gardening can be a challenge in northcentral Montana.