O'Fallon, MO Planting Dates — Moon Phase Garden

The four dates that matter

Date	When	What it means
Last spring frost (50%)	Apr 10	Half of all years see a freeze after this date. It is an average, not a guarantee.
Last spring frost (10%)	Apr 26	Only one year in ten freezes after this. Use it for anything you cannot afford to replant.
First fall frost (50%)	Oct 26	Half of all years freeze before this date. Fall crops are counted back from here.
First fall frost (10%)	Oct 13	An early-freeze year. If a crop must finish, aim to harvest before this.

USDA zone 6b 199 frost-free days Modelled estimate

Spring & summer planting in O'Fallon

Dates are calculated from this location's own last-frost date, not from a generic zone chart. “Best moon days” are the days inside each window that fall in the crop's traditional phase — the same rule the app uses.

Crop	Start seed indoors	Plant outdoors	Best moon days	Days to harvest
Strawberry (crowns) transplant	—	Feb 9 – Mar 20	Mar 3 Full Moon	perennial — first real harvest next season
Garlic cloves/sets Better planted in fall — see below	—	Feb 22 – Mar 25	Mar 4–9 Waning Gibbous	240–300
Asparagus (crowns) transplant	—	Feb 27 – Apr 3	Mar 25 First Quarter	perennial — first real harvest 2–3 years
Chives either	Feb 13	Feb 27 – Apr 3	Mar 19–24 Waxing Crescent	75–90
Onion (from sets/transplants) cloves/sets	—	Feb 27 – Apr 3	Mar 4–9 Waning Gibbous	90–120
Peas (English/snap) direct sow	—	Feb 27 – Apr 3	Mar 25 First Quarter	55–75
Spinach direct sow	—	Feb 27 – Apr 3	Mar 19–24 Waxing Crescent	35–50
Cabbage transplant	Feb 6	Mar 6 – Apr 3	Mar 19–24 Waxing Crescent	65–90
Collards either	Feb 27	Mar 6 – Apr 24	Mar 19–24 Waxing Crescent	55–85
Kale either	Feb 27	Mar 6 – Apr 10	Mar 19–24 Waxing Crescent	50–65
Lettuce (leaf) either	Mar 6	Mar 6 – May 1	Mar 19–24 Waxing Crescent	40–55
Potato cloves/sets	—	Mar 6 – Apr 10	Apr 1 Full Moon	70–120
Radish direct sow	—	Mar 6 – May 1	Mar 6–10, Apr 2 Waning Gibbous	22–35
Turnip direct sow	—	Mar 6 – Apr 17	Mar 6–10, Apr 2 Waning Gibbous	40–60
Broccoli transplant	Feb 6	Mar 11 – Apr 10	Mar 19–24 Waxing Crescent	55–80
Brussels Sprouts transplant	Feb 6	Mar 11 – Apr 10	Mar 19–24 Waxing Crescent	90–110
Leek transplant	Jan 30	Mar 11 – Apr 10	Apr 2–7 Waning Gibbous	100–120
Lettuce (head) transplant	Feb 20	Mar 11 – Apr 10	Mar 19–24 Waxing Crescent	60–85
Parsley either	Feb 6	Mar 11 – Apr 17	Mar 19–24 Waxing Crescent	70–90
Parsnip direct sow	—	Mar 11 – Apr 17	Apr 1 Full Moon	100–150
Shallot cloves/sets Better planted in fall — see below	—	Mar 11 – Apr 10	Apr 2–7 Waning Gibbous	90–120
Beet direct sow	—	Mar 13 – May 1	Apr 1, May 1 Full Moon	50–65
Kohlrabi either	Feb 27	Mar 13 – Apr 17	Mar 19–24 Waxing Crescent	45–60
Carrot direct sow	—	Mar 20 – May 1	Apr 1, May 1 Full Moon	65–85
Cauliflower transplant	Feb 6	Mar 20 – Apr 10	Mar 20–24 Waxing Crescent	55–80
Cilantro direct sow	—	Mar 20 – May 1	Mar 20–24, Apr 18 Waxing Crescent	45–70
Swiss Chard direct sow	—	Mar 20 – May 10	Mar 20–24, Apr 18 Waxing Crescent	50–60
Dill direct sow	—	Mar 27 – May 10	Apr 18–22 Waxing Crescent	40–60
Cucumber either	Mar 20	Apr 10 – May 10	Apr 23 First Quarter	50–70
Green Beans (bush) direct sow	—	Apr 10 – May 25	Apr 23, May 23 First Quarter	50–65
Oregano transplant	Feb 13	Apr 10 – May 1	Apr 23 First Quarter	cut as needed
Sage transplant	Feb 13	Apr 10 – May 1	Apr 23 First Quarter	cut as needed
Sweet Corn direct sow	—	Apr 10 – May 25	Apr 23, May 23 First Quarter	60–100
Thyme transplant	Feb 13	Apr 10 – May 1	Apr 23 First Quarter	cut as needed
Zucchini / Summer Squash either	Mar 20	Apr 10 – May 10	Apr 23 First Quarter	45–60
Basil either	Feb 27	Apr 17 – May 10	Apr 18–22 Waxing Crescent	30–60
Dry Beans direct sow	—	Apr 17 – May 15	Apr 23 First Quarter	85–100
Pole Beans direct sow	—	Apr 17 – May 20	Apr 23 First Quarter	60–75
Pumpkin direct sow	Mar 20	Apr 17 – May 15	Apr 23 First Quarter	90–120
Rosemary transplant	Apr 10	Apr 17 – May 10	Apr 23 First Quarter	cut as needed
Tomatillo transplant	Feb 27	Apr 17 – May 10	Apr 23 First Quarter	60–75
Tomato transplant	Feb 27	Apr 17 – May 10	Apr 23 First Quarter	60–85
Winter Squash direct sow	Mar 20	Apr 17 – May 15	Apr 23 First Quarter	85–110
Cantaloupe / Muskmelon either	Mar 20	Apr 24 – May 15	— First Quarter	75–90
Eggplant transplant	Feb 13	Apr 24 – May 15	— First Quarter	60–90
Okra direct sow	Mar 13	Apr 24 – May 20	— First Quarter	50–70
Pepper transplant	Feb 13	Apr 24 – May 15	— First Quarter	60–90
Sweet Potato slips	—	Apr 24 – May 20	May 2–7 Waning Gibbous	90–150
Watermelon either	Mar 20	Apr 24 – May 15	— First Quarter	70–90

Fall planting in O'Fallon

Fall dates count backward from the first frost, and they add time back for the “fall factor” — days are shortening and cooling, so a crop grows slower than the seed packet promises. Sowing late is the single most common way a fall garden fails.

Crop	Sow or set out	Best moon days	Days to harvest	Hardiness
Tomato	Jun 10 – Jul 16	Jun 21	60–85	very tender
Brussels Sprouts	Jun 13 – Jun 30	Jun 15–20	90–110	hardy
Potato	Jun 18 – Jul 20	Jun 29	70–120	semi-hardy
Sweet Corn	Jun 23 – Jul 16	—	60–100	tender
Pole Beans	Jul 3 – Jul 16	—	60–75	tender
Parsley	Jul 6 – Jul 20	Jul 15–20	70–90	semi-hardy
Okra	Jul 8 – Aug 7	Jul 21	50–70	very tender
Cabbage	Jul 13 – Jul 25	Jul 15–20	65–90	hardy
Carrot	Jul 13 – Jul 25	—	65–85	semi-hardy
Collards	Jul 13 – Aug 4	Jul 15–20	55–85	hardy
Cucumber	Jul 13 – Jul 26	Jul 21	50–70	tender
Broccoli	Jul 18 – Aug 4	Jul 18–20	55–80	hardy
Cauliflower	Jul 18 – Aug 4	Jul 18–20	55–80	semi-hardy
Green Beans (bush)	Jul 18 – Jul 26	Jul 21	50–65	tender
Lettuce (head)	Jul 18 – Jul 30	Jul 18–20	60–85	semi-hardy
Peas (English/snap)	Jul 18 – Aug 4	Jul 21	55–75	hardy
Beet	Jul 23 – Aug 9	Jul 29	50–65	semi-hardy
Kale	Jul 23 – Aug 9	—	50–65	hardy
Swiss Chard	Jul 23 – Aug 9	—	50–60	semi-hardy
Zucchini / Summer Squash	Jul 23 – Jul 31	—	45–60	tender
Basil	Jul 28 – Aug 15	Aug 13–15	30–60	very tender
Kohlrabi	Jul 28 – Aug 14	Aug 13–14	45–60	hardy
Cilantro	Aug 2 – Aug 14	Aug 13–14	45–70	semi-hardy
Lettuce (leaf)	Aug 2 – Aug 19	Aug 13–18	40–55	semi-hardy
Turnip	Aug 2 – Aug 19	Aug 2–4	40–60	hardy
Spinach	Aug 7 – Aug 24	Aug 13–18	35–50	hardy
Dill	Aug 12 – Aug 19	Aug 13–18	40–60	semi-hardy
Radish	Aug 12 – Sep 6	Aug 28–Sep 2	22–35	hardy
Garlic	Sep 26 – Nov 16	Sep 27–Oct 2	240–300	hardy
Shallot	Oct 10 – Nov 10	Oct 26–31	90–120	hardy

Bottom line: the 50% frost date is a coin flip, not a green light. If you would be sick about losing a flat of tomatoes, plant to the Apr 26 date instead and keep a row cover handy either way.

Where these numbers come from

There is no long-record weather station inside O'Fallon itself, so these frost dates are modelled, not observed. They come from a half-degree climate grid built by fitting the freeze dates of 6,808 NOAA stations (1991–2020 Normals) against terrain and the USDA 2023 hardiness raster, then reading the cell your city sits in. Checked against the stations themselves, that model lands within about a week on average — and its zone matches the station's exactly 67% of the time and within one half-zone 97% of the time. A cell covers roughly 35 by 28 miles, so this is a neighborhood answer, not a backyard one. If there is a station-backed location near you, prefer it.

How precise is any of this?

Extension recommendations for the same crop routinely disagree by two to four weeks, and occasionally more, so these offsets should be presented as windows and starting points rather than deadlines. Three things drive the spread. (1) Regional risk tolerance: for warm-season crops, Colorado State and Utah State put tomatoes, peppers and melons out about 14 days after the last frost, while University of Missouri's calendar works out to roughly 25-35 days after the last frost and University of Maryland's window runs from the frost date itself out to 45 days past it. That is a real 6-week spread for the single most popular garden crop, and it exists because a short-season mountain state is optimizing against a short season while a humid continental state is optimizing against cold, wet spring soil. (2) Soil temperature versus calendar date: most Extension services now say the honest trigger is soil temperature at 4 inches, not the frost date, and the frost-relative number is a convenience translation. A cold, wet spring can push the real date two or three weeks past the calendar recommendation. (3) Days-to-maturity is variety-specific and is measured differently for direct-seeded versus transplanted crops - seed catalogs count from transplant date for tomatoes, peppers, eggplant and cole crops, but from sowing for roots and greens - so a 'days to maturity' range of 60-85 for tomato is genuinely 60-85 depending on which packet you bought. Additionally, the average last frost is a 50% probability, meaning half of all years have a frost after that date; Extension services commonly advise waiting 1-2 weeks past it for anything frost-tender, or being prepared to cover. Treat every number here as plus or minus about 10-14 days.

On the station itself: a weather station is one point. Cities hold their heat, valleys pool cold air, and a garden on a north slope can run two weeks behind one a mile away. Treat this page as your starting point and let your own garden correct it — that is exactly what the journal in the app is for.

Nearby locations

St. Louis, MO zone 7a Columbia, MO zone 6b Springfield, IL zone 6a Peoria, IL zone 5b North Peoria, IL zone 5b Champaign, IL zone 6a

Want this on your phone, in your garden? Moon Phase Garden keeps your frost dates, your planting windows and tonight's moon phase in one place, works offline, and lets you override these dates with what your own garden actually does. Free and ad-free.

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