Zone 3B is a cold northern climate with a productive summer growing season. With an average last spring frost around May 15 and first fall frost around Sep 15, you have approximately 123 frost-free days per year. Use the planting dates below to plan your garden around these key frost windows. For a personalized forecast based on your specific zip code, use our free planting calendar. Browse individual plant guides for detailed growing instructions, or explore how USDA zones work to better understand your growing conditions.