Des Moines, IA Frost Dates
Average frost dates, USDA hardiness zone, and growing season length for Des Moines, Iowa.
Gardening in Des Moines
Iowa's capital sits on some of the richest topsoil on the planet — 300+ years of prairie grass decomposition created the black gold that made Iowa the agricultural powerhouse it is. Des Moines gardeners don't need to amend their soil. They need to appreciate it.
Classic Midwest four-season climate with 163 frost-free days. Iowa winters are genuine (single digits are routine), but the payoff is rich, deep, naturally fertile soil that grows food with almost suspicious ease. The long summer days and adequate rainfall mean that once you plant, things just grow. The biggest weather threats are late spring frost and summer hailstorms.
Iowa State's extension service is gardening's equivalent of an Ivy League education — the research is that good. The Downtown Farmers' Market is one of the largest in the Midwest. And the Iowa State Fair's agricultural competitions are taken with a seriousness that borders on religious. Your Big Boy tomato isn't just a tomato — it's a contender.
What This Means for Des Moines Gardeners
The average last spring frost in Des Moines is around April 28, and the average first fall frost arrives around October 8. That gives you approximately 163 frost-free days to work with.
At 163 days, you're working with a compressed but productive window. Choose varieties by their days-to-maturity number — anything under 75 days is safe, 75-90 requires indoor starting, and 90+ is a calculated risk. The tradeoff: your cool, moderate summers are excellent for crops that heat-zone gardeners struggle with. Your lettuce doesn't bolt in June. Your peas produce for weeks longer. Cool-season crops are your superpower.
These dates are based on NOAA 30-year Climate Normal data for the Des Moines area. Your actual frost dates could shift 2-3 weeks in either direction in any given year. Learn more about our data sources.
What to Grow in Des Moines
Des Moines's 163-day season gives you plenty of time for most vegetables with good planning. Start warm-season crops indoors to maximize your window. Cool-season crops thrive in your spring and fall shoulder seasons. Recommended starting points: tomatoes, peppers, lettuce, carrots, beans, broccoli, garlic, and basil.
See the full Iowa planting guide for all 40 plants: Iowa Planting Calendar. Or enter your zip code for exact planting dates personalized to Des Moines.
More About Zone 5B
Des Moines is in USDA Hardiness Zone 5B, which means average annual extreme minimum temperatures between -15°F to -10°F. View the full Zone 5B planting guide.
See the complete planting calendar for Iowa: Iowa Planting Calendar.
Other Cities in Iowa
Frequently Asked Questions
These dates are based on NOAA's 30-year Climate Normal data for the Des Moines area. They represent historical averages, not predictions. In any given year, the actual last frost could be 2-3 weeks earlier or later. Microclimates within Des Moines (urban heat islands, hilltops, low-lying valleys) can also shift your local frost dates by a week or more.
Start warm-season seeds indoors 6-8 weeks before your last frost (April 28) to maximize your 163-day window. Direct sow cold-hardy crops like peas and lettuce 3-4 weeks before last frost. Every week of early indoor starting matters at this season length. Enter your zip code for exact dates.