USDA Hardiness Zone 5A spans a wide swath of the central United States — including much of Iowa, Illinois, Ohio, Pennsylvania, and Colorado's Front Range — with average annual minimum temperatures between -20°F and -15°F. The growing season averages 166 frost-free days between a last spring frost around Apr 25 and first fall frost near Oct 8. This is a versatile zone: warm-season crops like tomatoes and peppers have ample time to mature, and cool-season crops can be planted in both spring and fall for two distinct harvests. 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.