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

Planting zone for 52768 — Princeton, IA

ZIP code 52768 (Princeton, Scott County) is in USDA zone 5b: the coldest winter night averages −15 to −10 °F. The median last spring frost is April 16 and the first fall frost October 25.

Where ZIP 52768 is

Outlined: the ZIP code area · 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.

Zone5b−15 to −10 °F
Coldest night−26.1 to −23.3 °C
Last frostApr 16
First frostOct 25
2012 zone5b

Same zone as on the 2012 map. The zone is the one at the center of the ZIP code; hilly ZIPs can span two zones. What zone 5b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Princeton, IA…

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 Princeton, IA

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 16median — 50% chance of a later frost
Safe for tender plantsApril 30only 10% chance of frost after
First fall frostOctober 25median — 10% chance by Oct 11
Growing season190 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 6 and returns around November 2.

From the NOAA station Le Claire L&D 14, IA — 9 miles away, elevation 577 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 52768

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 5 – Mar 19
SpinachSow outdoors · Mar 5 – Mar 26
Broccoli, cabbageStart indoors · Feb 5 – Feb 19
Broccoli, cabbageTransplant · Mar 26 – Apr 9
Onion setsPlant outdoors · Mar 19 – Apr 2
PotatoesPlant outdoors · Mar 26 – Apr 9
LettuceSow outdoors · Mar 19 – Apr 2
Carrots, beetsSow outdoors · Mar 26 – Apr 9
TomatoesStart indoors · Feb 19 – Mar 5
TomatoesTransplant · Apr 23 – May 7
Peppers, eggplantStart indoors · Feb 5 – Feb 19
Peppers, eggplantTransplant · Apr 30 – May 14
BeansSow outdoors · Apr 23 – May 7
Sweet cornSow outdoors · Apr 23 – May 7
Cucumbers, squashSow outdoors · Apr 23 – May 7
Fall lettuce, spinachSow outdoors · Aug 30 – Sep 13
GarlicPlant cloves · Oct 11 – Nov 15
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 16) and first fall frost (Oct 25) 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 52768 came on Mar 25 — 11 days earlier than the 1991–2020 average (Apr 5).

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 5b in Iowa

473 plants native to the lower 48 states, recorded in Iowa, and rated by the USDA to survive −15 °F or colder — the bottom of zone 5b. Each links to its USDA PLANTS profile.

Trees 49

American basswood100 ft · blooms late spring · low shade tolerance · to −46 °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 °Farborvitae50 ft · blooms mid spring · medium shade tolerance · to −33 °Fbalsam fir60 ft · blooms mid summer · low shade tolerance · to −43 °F

Shrubs 77

alderleaf buckthorn3 ft · blooms late spring · low shade tolerance · to −33 °FAllegheny serviceberry35 ft · blooms early spring · low shade tolerance · to −38 °Falternateleaf dogwood25 ft · blooms mid spring · low shade tolerance · to −47 °FAmerican black currant3 ft · blooms early spring · to −46 °FAmerican hazelnut10 ft · blooms spring · medium shade tolerance · to −33 °FAmerican hornbeam30 ft · blooms mid spring · low shade tolerance · to −34 °F

Wildflowers & perennials 191

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 136

arctic brome3 ft · blooms early summer · low shade tolerance · to −33 °Fawlfruit sedge4 ft · blooms mid spring · low shade tolerance · to −38 °FBebb's sedge3 ft · blooms late 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 °Fblue grama1 ft · blooms early summer · high shade tolerance · to −43 °F

Vines 7

American bittersweet15 ft · blooms spring · low shade tolerance · to −38 °Fdevil's darning needles15 ft · blooms mid summer · medium shade tolerance · to −38 °Ffrost grape83 ft · blooms late spring · medium shade tolerance · to −23 °Friverbank grape45 ft · blooms late spring · medium shade tolerance · to −33 °Fsummer grape30 ft · blooms late spring · low shade tolerance · to −23 °Ftrumpet honeysuckle16 ft · blooms late summer · low shade tolerance · to −33 °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 Princeton, IA.

Soil in Princeton, IA

The soil mapped at the center of ZIP 52768 is Dockery — silt loam, somewhat poorly drained.

TextureSilt loama good balance for most vegetables
pH6.5neutral; most vegetables like 6.0–7.0
DrainageSomewhat poorly drainedconsider raised beds
Organic matter2%moderate
Hydrologic groupB/Dmoderate when drained; wet otherwise
Farmland classprime farmlandUSDA classification

Map unit: Dockery silt loam, 0 to 2 percent slopes, occasionally flooded.

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 52768; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Princeton, IA

Summer high85 °Faverage high, July
Winter low14 °Faverage low, January
Hot days18days a year at 90 °F or more
Freezing nights126nights a year at 32 °F or less
Growing degree days3,395base 50 °F — the season’s usable heat
Longest day15 h 12 mindaylight on June 21
Shortest day9 h 09 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation38.8 inper year, rain and melted snow

Average high and low, by month

0°10°20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 31 °F, low 14 °F 31°14° JanFebruary: average high 35 °F, low 18 °F 35°18° FebMarch: average high 47 °F, low 28 °F 47°28° MarApril: average high 61 °F, low 40 °F 61°40° AprMay: average high 72 °F, low 52 °F 72°52° MayJune: average high 82 °F, low 62 °F 82°62° JunJuly: average high 85 °F, low 66 °F 85°66° JulAugust: average high 83 °F, low 64 °F 83°64° AugSeptember: average high 77 °F, low 56 °F 77°56° SepOctober: average high 64 °F, low 44 °F 64°44° OctNovember: average high 48 °F, low 31 °F 48°31° NovDecember: average high 36 °F, low 21 °F 36°21° Dec

Precipitation by month inches

0″1″2″3″4″5″January: 1.56 in precipitation 1.6 JanFebruary: 1.85 in precipitation 1.9 FebMarch: 2.57 in precipitation 2.6 MarApril: 3.69 in precipitation 3.7 AprMay: 4.90 in precipitation 4.9 MayJune: 4.93 in precipitation 4.9 JunJuly: 4.49 in precipitation 4.5 JulAugust: 4.19 in precipitation 4.2 AugSeptember: 3.49 in precipitation 3.5 SepOctober: 2.87 in precipitation 2.9 OctNovember: 2.29 in precipitation 2.3 NovDecember: 2.00 in precipitation 2.0 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Le Claire L&D 14, IA (9 mi away); precipitation: Le Claire 1.8 Nne, IA (6 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 5b.

527585b
Mc Causland, IA · 4 mi
527535b
Le Claire, IA · 5 mi
612425b
Cordova, IL · 5 mi
527305b
Camanche, IA · 6 mi
527575b
Low Moor, IA · 7 mi
612755b
Port Byron, IL · 8 mi
527565b
Long Grove, IA · 8 mi
612785b
Rapids City, IL · 9 mi

Iowa planting zones →

Questions about 52768

What planting zone is ZIP code 52768?

ZIP code 52768 (Princeton, IA) is in USDA hardiness zone 5b on the 2023 map: the coldest night of an average winter reaches −15 to −10 °F (−26.1 to −23.3 °C).

When is the last frost in Princeton, IA?

The median last spring frost (32 °F) near 52768 is April 16; after April 30 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Le Claire L&D 14 station.

When is the first frost in Princeton, IA?

The median first fall frost near 52768 is October 25, giving a median frost-free growing season of 190 days.

When should I plant tomatoes in 52768?

Start tomato seeds indoors around Feb 19 – Mar 5 and set transplants outside around Apr 23 – May 7, one to three weeks after the median last frost.

How much rain and snow does 52768 get?

About 38.8 inches of precipitation a year (NOAA 1991–2020 normals, Le Claire 1.8 Nne station).

How hot do summers get in Princeton, IA?

The average high peaks at 85 °F in July, with about 18 days a year at 90 °F or more.

What kind of soil does 52768 have?

The USDA soil survey maps Dockery at the center of ZIP 52768: silt loam, somewhat poorly drained, pH about 6.5 (neutral).

Did spring come early in Princeton, IA in 2026?

Spring leaf-out near 52768 came on Mar 25 in 2026, 11 days earlier than the 1991–2020 average (Apr 5), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Princeton, IA?

Long-day onions: the longest day near 52768 is 15 h 12 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).