USDA Hardiness Zone 4A covers much of Minnesota, Wisconsin, Montana, and northern Maine, with average annual minimum temperatures between -30°F and -25°F. The growing season averages 140 frost-free days between a last spring frost around May 8 and first fall frost near Sep 25. Most warm-season vegetables — tomatoes, peppers, squash — succeed when started indoors and transplanted after the frost date. Cool-season crops such as peas, lettuce, and radishes can be direct-sown several weeks before the last frost for an early harvest. 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.