Frost Dates for Saint Clair, MO 63077

Last spring frost April 22 · First fall frost October 9 · 170 frost-free days · USDA Zone 6b

Frost probability for 63077

Frost10%50%90%
Spring (last frost)May 8April 22April 6
Fall (first frost)September 25October 9October 22

Dates come from NOAA 1971–2000 freeze probabilities at the nearest reporting station (13.2 km away); the 50% date is the median year.

Month by month in Saint Clair

MonthWhat to do
JanuaryPlan your garden layout and order seeds. Research varieties suited to your frost dates.
FebruaryStart peppers and eggplant indoors 8–10 weeks before your last frost (around April 22). Start tomatoes about two weeks later, 6–8 weeks before last frost.
MarchStart herbs, basil, and squash indoors (4–6 weeks before frost). Direct sow peas, spinach, and lettuce if soil is workable.
AprilLast frost around April 22. Transplant cold-hardy crops (broccoli, kale, cabbage). Harden off tomato and pepper seedlings.
MayFrost has passed. Transplant tomatoes, peppers, and basil outdoors. Direct sow beans, cucumbers, squash, and zucchini.
JuneSuccession plant lettuce and greens. Keep beds weeded and watered consistently.
JulyHarvest regularly to encourage production. Monitor for pests and disease.
AugustMidsummer: harvest beans, zucchini, cucumbers. Start brassica seeds indoors for fall.
SeptemberFirst fall frost approaching (around October 9). Transplant fall brassicas. Sow spinach, arugula, and radishes.
OctoberFirst frost around October 9. Harvest tomatoes and peppers before frost. Cover cold-hardy crops with row covers to extend the season.
NovemberHarvest remaining cold-hardy crops: kale, carrots, and beets. Plant garlic bulbs for next year.
DecemberClean up spent plants. Add compost to beds. Rest, review, and plan next year's garden.

What grows in a 170-day season

Frequently Asked Questions

What is the last frost date for Saint Clair, MO (ZIP 63077)?

The median last spring frost date for Saint Clair, MO (ZIP code 63077) is around April 22. This is the 50th-percentile date — meaning half of all years see frost end before this date. Use the 10% and 90% dates to understand the full range of risk in your area.

What is the first fall frost date in Saint Clair, MO?

The median first fall frost date for Saint Clair, MO is around October 9. Plan to harvest or protect frost-sensitive crops like tomatoes and peppers at least a week before this date to avoid losses.

How long is the growing season in Saint Clair, MO?

The frost-free growing season in Saint Clair is about 170 days. This window — from your last spring frost to your first fall frost — is when warm-season vegetables thrive. Cold-hardy crops like kale, spinach, and peas can extend your season by weeks on either side.

What USDA hardiness zone is Saint Clair, MO?

Based on frost date patterns, Saint Clair falls approximately in 6b. USDA hardiness zones are determined by average annual minimum winter temperatures and guide both plant selection and planting timing for your location.

When should I start tomatoes indoors in Saint Clair, MO?

Start tomato seeds indoors 6–8 weeks before your last frost date (around April 22). For Saint Clair, that's roughly February 26 to March 11. Transplant outdoors 1–2 weeks after your last frost.

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