St. Louis, MO Frost Dates
Average frost dates, USDA hardiness zone, and growing season length for St. Louis, Missouri.
Gardening in St. Louis
St. Louis gardening has Gateway Arch-level ambition — the city's rich Mississippi and Missouri River bottomland has been growing food since before the Louisiana Purchase. The city's diverse neighborhoods each bring their own garden traditions, from The Hill's Italian vegetable plots to North County's soul food gardens.
The Mississippi Valley heat and humidity make St. Louis one of the warmest cities in the Midwest. Your 193-day growing season is generous for the region. Summer can feel subtropical — 95°F with matching humidity — which grows extraordinary tomatoes and peppers but also invites every fungal disease in the Midwest playbook. The clay soil is heavy but incredibly fertile once amended.
Cardinals fans have the best fans-in-baseball reputation, and St. Louis gardeners bring the same committed, knowledgeable energy. The Soulard Farmers Market, operating since 1779, claims to be the oldest west of the Mississippi. Tower Grove Park's community gardens are some of the most diverse in the country. And The Hill's backyard tomato plots are an Italian-American tradition that predates most of the restaurants they now supply.
What This Means for St. Louis Gardeners
The average last spring frost in St. Louis is around April 10, and the average first fall frost arrives around October 20. That gives you approximately 193 frost-free days to work with.
A solid, workable season. Most standard vegetable varieties have enough time to mature, though the longest-season crops (like sweet potatoes at 90+ days or large watermelons at 85+ days) need to be started early and chosen carefully. Indoor seed starting isn't optional — it's how you buy the extra weeks that make the difference between a good harvest and a great one.
These dates are based on NOAA 30-year Climate Normal data for the St. Louis 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 St. Louis
St. Louis's 193-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 Missouri planting guide for all 40 plants: Missouri Planting Calendar. Or enter your zip code for exact planting dates personalized to St. Louis.
More About Zone 6B
St. Louis is in USDA Hardiness Zone 6B, which means average annual extreme minimum temperatures between -5°F to 0°F. View the full Zone 6B planting guide.
See the complete planting calendar for Missouri: Missouri Planting Calendar.
Other Cities in Missouri
Frequently Asked Questions
These dates are based on NOAA's 30-year Climate Normal data for the St. Louis 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 St. Louis (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 10) to maximize your 193-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.