When to Plant a Fall Garden in Missouri: Frost-Date Calculator by Crop Type

To plant a fall garden in Missouri, start 4-6 weeks before the first frost—typically mid-August to mid-September for most of the state.

Missouri’s unpredictable fall weather can make or break your harvest—plant too early, and frost ruins your crops; too late, and you miss the growing window. But timing your fall garden just right means bumper crops of leafy greens, root vegetables, and cool-season favorites by Thanksgiving.

With USDA zones 5b-6b and average first frosts between September 15 and October 30, your planting schedule hinges on knowing your local frost date and choosing fast-maturing varieties. Skip the guesswork and get the exact weeks before frost for 15+ crops in Missouri’s climate.

Below, I’ll break down the best planting times for your region, how to adjust for microclimates (like urban vs. rural frost risks), and the 5 mistakes that waste Missouri gardeners’ fall efforts—so you can harvest fresh greens and roots straight through November.

Missouri’s fall planting timeline by first frost date (with exact weeks before frost)

Missouri’s USDA zones 5b-6b give gardeners a 6-8 week window for fall planting, but timing is everything. The average first frost arrives between September 15 (northern MO) and October 30 (southern MO), so I’ve calculated exact planting windows for 15+ cold-hardy crops.

Plant too early, and your bush beans bolt; too late, and your kale won’t mature before frost.

For optimal harvests, aim to plant 4-6 weeks before frost for fast growers like radishes (25 days) and spinach (40 days), while slower crops like broccoli (60-80 days) need a head start.

Missouri State University’s frost data shows St. Louis typically gets a 7-10 day delay compared to rural areas—so adjust your schedule if you’re in the city.

Use this heat-unit rule: Most fall crops need 800-1,200 growing degree days (GDD) after planting. For example, carrots (700 GDD) can handle cooler temps, while lettuce (600 GDD) thrives in mild fall weather. Check your local first frost date and work backward to calculate your planting window.

Here’s my Missouri Fall Planting Timeline based on average frost dates, organized by crop type and weeks before frost. I’ve included cold-hardy options that survive light frosts (28°F) and tender crops that need protection or earlier planting.

For cold-hardy crops like kale, Swiss chard, and radishes, urban gardeners can push their planting dates later because the heat island effect creates a longer growing season. However, rural gardeners should start these crops 2–3 weeks earlier to ensure they mature before the first frost.

If you’re unsure about your local frost date, use a seedling thermometer to monitor soil temperatures—ideal planting soil should be between 50–65°F for most fall crops.

Pro tip: If you’re in a transition zone between urban and rural (like Columbia or Springfield), average the frost dates from both categories.

For example, if rural frost is October 1 and urban frost is October 10, aim for a midpoint planting date of September 25 for heat-sensitive crops like lettuce. This flexibility ensures your fall garden thrives regardless of where you live in Missouri.

Don’t forget to monitor local weather forecasts in late September. A sudden cold snap can arrive earlier than expected, so have row covers or cold frames ready to protect tender crops like baby carrots or peas.

With these adjustments, you’ll harvest fresh, homegrown vegetables well into November—even if you’re gardening in the heart of St. Louis or the rolling hills of the Ozarks.