St. Louis frost dates and planting season

Name: St. Louis
Address: Missouri, United States

When to plant vegetables here. Cover calendars (fleece, cold frame, unheated greenhouse) are on each plant’s when-to-plant page.

St. Louis has a moderate growing season, with roughly 197 frost-free days between the typical frost dates. Typical last spring frost: around April 18 (half of years later). Typical first fall frost: around November 2. Plant cool-season crops after about March 9; wait until about April 27 for warm-season crops.

Frost-free days197Apr 18 – Nov 2

Frost-free season in St. Louis. Based on average frost dates. Adjust a week or two for your conditions.

Cover calendars (fleece, cold frame, unheated greenhouse) live on each crop’s when-to-plant page.

Weekly possible temperature−5 – 101 °F

Frost-free days197

Typical last spring frostApril 18

Typical first fall frostNovember 2

Days suitable for warm-season vegetables182 (April 27 – October 25)

Days suitable for cool-season vegetables147 (March 9 – May 31; September 21 – November 22)

Calculated by Plan & Plant · Method · Data 2019–2026

Frost and suitability dates are typical figures from climate statistics. Microclimates vary; they are not a guarantee.

Frost dates calculated by Plan & Plant from Weather data by Open-Meteo.com (CC BY 4.0). Local frost pockets, valleys and coastal sites can differ by 1–3 weeks.

How we calculated this

Data: ERA5-Land via Open-Meteo, cell 38.63, -90.20, years 2019–2026 (not a 30-year climate normal yet).
Typical and safer dates: Typical last frost is the date after which half of winters in this sample had no more frost; safer is later in the sample so fewer winters still frosted.
Confidence: Provisional — short or thin sample for this place.
Full methodology (algorithm 2026-10-season-6).

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What to plant when

Cool-season vegetables

Earliest outdoor start: March 9

Suitable window: March 9 – May 31; September 21 – November 22

Cool-season crops prefer cooler weather.

Midsummer is often too hot, so suitable weeks split into more than one window.

See cool-season details

Warm-season vegetables

Earliest outdoor start: April 27

Suitable window: April 27 – October 25

Warm-season crops need mild or warm weather and cannot take frost.

Frost kills these crops, and cold snaps set them back.

See warm-season details

Green = usually good weeks to grow; blue or gray = usually too cold for that crop type.

Starter plants for St. Louis

Cool-season

Radish Sow: March 7 – May 30; September 13 – October 12 Planting dates
Arugula Sow: March 7 – May 30; September 13 – September 29 Planting dates
Spinach Sow: March 7 – May 30 Planting dates
Lettuce Sow: March 7 – May 30 Planting dates
Kale Sow: March 7 – May 1 Planting dates
Beet Sow: March 21 – August 4 Planting dates

Warm-season

Zucchini Sow: May 11 – July 5 Planting dates
Cucumber Sow: May 11 – July 5 Planting dates
Green bean Sow: May 9 – July 26 Planting dates
Tomato Transplant: May 5 – June 27 Start indoors, then transplant. Planting dates
Bell pepper Transplant: May 11 – June 22 Start indoors, then transplant. Planting dates

How these dates are judged

Last frost: The typical last spring date when frost is still expected.
First frost: The typical first fall date when frost returns.
Frost-free days: The approximate days between those two dates.
Cool-season vegetables: Crops that prefer cooler weather, such as lettuce, kale, peas, and radish.
Warm-season vegetables: Crops that need warm weather and cannot take frost, such as tomato, pepper, squash, and beans.

Cool-season planting window

Mar 9 – May 31; Sep 21 – Nov 22 (147 days)

Warm-season planting window

Apr 27 – Oct 25 (182 days)

Usually too cold

January 1 – March 8
November 23 – December 31

Weekly temperatures and planting windows

Temperatures across the year for St. Louis, with cool- and warm-season weeks and frost dates.

Possible min to max
Average min to max
Suitable
Tolerable
Too cold
Too hot

Selected week · tap a week or use the arrows

Week 11 · Mar 9 – Mar 15

Average 40 to 58 °F · Possible 16 to 80 °F

Cool season: tolerable

Warm season: too cold

A week is suitable for a crop type when its average low and high sit inside that type's range and its possible readings stay within the frost and heat limits (cool: 28 °F to 81 °F, warm: 32 °F to 90 °F); crossing a limit makes it tolerable, and for warm crops any chance of frost makes it too cold.

Based on average frost dates.

Missouri, United States · 38.62727, -90.19789 · 2026

Coldest weekly possible temperature−5 °F

Hottest weekly possible temperature101 °F

Last expected spring frostApril 18

First expected fall frostNovember 2

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