Data: 2023 USDA zones (PRISM/OSU) · NOAA 1991–2020 normals · updated

Planting zone for Saint Charles, MO

Saint Charles, MO is in USDA zones 6b to 7a across its 4 ZIP codes. The median last spring frost is April 8 and the first fall frost October 29.

Saint Charles on the zone map

Outlined: its 3 ZIP code areas · tap the map for the zone at any spot · scroll or pinch to zoom

Not the official USDA Plant Hardiness Zone Map. Zones come from the 2023 USDA hardiness-zone data by the PRISM Group, Oregon State University; we re-mapped and recolored them. The official map is at planthardiness.ars.usda.gov.

Zones6b–7a−5 to 5 °F
ZIP codes4
Last frostApr 8
First frostOct 29
Growing season203 days

6b 2 ZIPs   7a 2 ZIPs

Frost forecast — next 7 nights

live from the National Weather Service

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Forecast data: National Weather Service (api.weather.gov), public domain. This is not a warning service — for official frost and freeze warnings see weather.gov.

Frost dates in Saint Charles, MO

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 8median — 50% chance of a later frost
Safe for tender plantsApril 24only 10% chance of frost after
First fall frostOctober 29median — 10% chance by Oct 16
Growing season203 daysfrost-free, median

A hard freeze (28 °F) usually ends around March 30 and returns around November 10.

From the NOAA station St Charles Elm Pt, MO, elevation 472 ft. NOAA NCEI U.S. Climate Normals 1991–2020, 32 °F threshold. Low spots and valleys can freeze later in spring than the station.

When to plant vegetables in Saint Charles

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Feb 25 – Mar 11
SpinachSow outdoors · Feb 25 – Mar 18
Broccoli, cabbageStart indoors · Jan 28 – Feb 11
Broccoli, cabbageTransplant · Mar 18 – Apr 1
Onion setsPlant outdoors · Mar 11 – Mar 25
PotatoesPlant outdoors · Mar 18 – Apr 1
LettuceSow outdoors · Mar 11 – Mar 25
Carrots, beetsSow outdoors · Mar 18 – Apr 1
TomatoesStart indoors · Feb 11 – Feb 25
TomatoesTransplant · Apr 15 – Apr 29
Peppers, eggplantStart indoors · Jan 28 – Feb 11
Peppers, eggplantTransplant · Apr 22 – May 6
BeansSow outdoors · Apr 15 – Apr 29
Sweet cornSow outdoors · Apr 15 – Apr 29
Cucumbers, squashSow outdoors · Apr 15 – Apr 29
Fall lettuce, spinachSow outdoors · Sep 3 – Sep 17
GarlicPlant cloves · Oct 15 – Nov 19
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 8) and first fall frost (Oct 29) with the rules of thumb U.S. extension services publish. Cool-season crops take a light frost; warm-season crops do best once the soil is above about 60 °F.

When spring arrived in 2026

In 2026, spring leaf-out near 63303 came on Mar 5 — 9 days earlier than the 1991–2020 average (Mar 14).

JanFebMarAprMayJun

The Spring Index marks the day when accumulated warmth is enough for lilac and honeysuckle to leaf out — a widely used signal that the growing season has started. Source: USA National Phenology Network, www.usanpn.org — Spring Indices, first leaf, 2026 (data as of 2026-09-08) and 30-year average 1991–2020 (CC BY 4.0).

Native plants for zone 6b in Missouri

525 plants native to the lower 48 states, recorded in Missouri, and rated by the USDA to survive −5 °F or colder — the bottom of zone 6b. Each links to its USDA PLANTS profile.

Trees 70

American basswood100 ft · blooms late spring · low shade tolerance · to −46 °FAmerican beech80 ft · blooms mid spring · low shade tolerance · to −44 °FAmerican chestnut115 ft · blooms early summer · high shade tolerance · to −33 °FAmerican elm120 ft · blooms early spring · medium shade tolerance · to −46 °FAmerican sycamore100 ft · blooms spring · medium shade tolerance · to −34 °Fbald cypress130 ft · blooms mid spring · medium shade tolerance · to −18 °F

Shrubs 83

alternateleaf dogwood25 ft · blooms mid spring · low shade tolerance · to −47 °FAmerican beautyberry6 ft · blooms early summer · medium shade tolerance · to −8 °FAmerican black currant3 ft · blooms early spring · to −46 °FAmerican hazelnut10 ft · blooms spring · medium shade tolerance · to −33 °FAmerican holly40 ft · blooms mid spring · low shade tolerance · to −20 °FAmerican hornbeam30 ft · blooms mid spring · low shade tolerance · to −34 °F

Wildflowers & perennials 192

alkali buttercup1 ft · blooms late spring · low shade tolerance · to −38 °FAmerican bur-reed3 ft · blooms indeterminate · medium shade tolerance · to −33 °FAmerican eelgrass1 ft · blooms mid summer · high shade tolerance · to −33 °FAmerican licorice4 ft · blooms late spring · medium shade tolerance · to −38 °FAmerican lotus3 ft · blooms mid summer · high shade tolerance · to −36 °FAmerican pokeweed7 ft · blooms mid summer · low shade tolerance · to −33 °F

Grasses 157

alkali sacaton3 ft · blooms mid summer · high shade tolerance · to −38 °FAmerican cupscale3 ft · blooms early summer · high shade tolerance · to −18 °Fawlfruit sedge4 ft · blooms mid spring · low shade tolerance · to −38 °FBicknell's sedge3 ft · blooms late spring · low shade tolerance · to −38 °Fbig bluestem6 ft · blooms summer · high shade tolerance · to −46 °Fblister sedge3 ft · blooms late spring · medium shade tolerance · to −38 °F

Vines 12

American bittersweet15 ft · blooms spring · low shade tolerance · to −38 °Fcatbird grape30 ft · blooms late spring · medium shade tolerance · to −13 °Fdevil's darning needles15 ft · blooms mid summer · medium shade tolerance · to −38 °Ffrost grape83 ft · blooms late spring · medium shade tolerance · to −23 °Fgraybark grape50 ft · blooms late spring · medium shade tolerance · to −8 °Fheartleaf peppervine2 ft · blooms late spring · low shade tolerance · to −8 °F

Source: USDA, NRCS. 2026. The PLANTS Database (plants.usda.gov), National Plant Data Team — state distribution, native status and the “Temperature, Minimum” characteristic. Check light, moisture and soil needs before buying; local nurseries and your state native plant society can confirm what thrives in Saint Charles, MO.

Soil in Saint Charles, MO

The soil mapped at the center of ZIP 63303 is Harvester — silt loam, moderately well drained.

TextureSilt loama good balance for most vegetables
pH7.2neutral; most vegetables like 6.0–7.0
DrainageModerately well drainednatural drainage class
Organic matter0.48%low — add compost
Hydrologic groupCwater soaks in slowly
Farmland classFarmland of statewide importanceUSDA classification

Map unit: Harvester-Urban land complex, 2 to 9 percent slopes.

Soil Survey Staff, Natural Resources Conservation Service, USDA. Soil Survey Geographic (SSURGO) Database, via Soil Data Access, accessed 2026-10-29. The soil at the center point of ZIP 63303; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Saint Charles, MO

Summer high88 °Faverage high, July
Winter low21 °Faverage low, January
Hot days39days a year at 90 °F or more
Freezing nights103nights a year at 32 °F or less
Growing degree days4,056base 50 °F — the season’s usable heat
Longest day14 h 53 mindaylight on June 21
Shortest day9 h 27 mindaylight on December 21
Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully
Precipitation42.3 inper year, rain and melted snow
Snowfall15 inper year; 17 days with snow on the ground

Average high and low, by month

10°20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 39 °F, low 21 °F 39°21° JanFebruary: average high 45 °F, low 25 °F 45°25° FebMarch: average high 56 °F, low 33 °F 56°33° MarApril: average high 67 °F, low 43 °F 67°43° AprMay: average high 76 °F, low 54 °F 76°54° MayJune: average high 84 °F, low 63 °F 84°63° JunJuly: average high 88 °F, low 68 °F 88°68° JulAugust: average high 87 °F, low 65 °F 87°65° AugSeptember: average high 81 °F, low 57 °F 81°57° SepOctober: average high 69 °F, low 45 °F 69°45° OctNovember: average high 55 °F, low 35 °F 55°35° NovDecember: average high 44 °F, low 27 °F 44°27° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″4″5″January: 2.44 in precipitation, 4.7 in snowfall 2.4❄5 JanFebruary: 2.37 in precipitation, 5 in snowfall 2.4❄5 FebMarch: 3.46 in precipitation, 1.5 in snowfall 3.5❄2 MarApril: 4.74 in precipitation, 0.1 in snowfall 4.7 AprMay: 4.80 in precipitation 4.8 MayJune: 4.26 in precipitation 4.3 JunJuly: 4.23 in precipitation 4.2 JulAugust: 3.76 in precipitation 3.8 AugSeptember: 3.07 in precipitation 3.1 SepOctober: 3.11 in precipitation 3.1 OctNovember: 3.54 in precipitation, 0.8 in snowfall 3.5❄1 NovDecember: 2.56 in precipitation, 2.7 in snowfall 2.6❄3 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: St Peters 2 Se, MO (3 mi away); precipitation: St Peters 2 Se, MO (3 mi away). Daylight is calculated from latitude.

ZIP codes in Saint Charles

633016b
−5 to 0 °F
633027a
0 to 5 °F
633037a
0 to 5 °F
633046b
−5 to 0 °F

Missouri planting zones →

Questions about Saint Charles

What planting zone is Saint Charles, MO?

Saint Charles, MO is in USDA hardiness zones 6b to 7a on the 2023 map (6b: −5 to 0 °F; 7a: 0 to 5 °F).

When is the last frost in Saint Charles, MO?

The median last spring frost is April 8 and the median first fall frost is October 29 (NOAA 1991–2020 normals, St Charles Elm Pt station).

When can I plant a garden in Saint Charles, MO?

Cool-season crops like peas and spinach go in around Feb 25 – Mar 18; tomatoes, peppers, beans and squash after about Apr 15, once frost risk has passed.

What kind of onions grow in Saint Charles, MO?

Intermediate onions: the longest day is 14 h 53 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

How much rain and snow does Saint Charles, MO get?

About 42.3 inches of precipitation a year and 15 inches of snowfall (NOAA 1991–2020 normals).