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

Planting zone for 50837 — Bridgewater, IA

ZIP code 50837 (Bridgewater, Adair County) is in USDA zone 5b: the coldest winter night averages −15 to −10 °F. The median last spring frost is April 25 and the first fall frost October 12.

Where ZIP 50837 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 25
First frostOct 12
2012 zone5a

Was 5a on the 2012 map — half a zone warmer now. 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 Bridgewater, 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 Bridgewater, IA

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 25median — 50% chance of a later frost
Safe for tender plantsMay 7only 10% chance of frost after
First fall frostOctober 12median — 10% chance by Sep 26
Growing season170 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 16 and returns around October 23.

From the NOAA station Greenfield, IA — 14 miles away, elevation 1,316 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 50837

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 14 – Mar 28
SpinachSow outdoors · Mar 14 – Apr 4
Broccoli, cabbageStart indoors · Feb 14 – Feb 28
Broccoli, cabbageTransplant · Apr 4 – Apr 18
Onion setsPlant outdoors · Mar 28 – Apr 11
PotatoesPlant outdoors · Apr 4 – Apr 18
LettuceSow outdoors · Mar 28 – Apr 11
Carrots, beetsSow outdoors · Apr 4 – Apr 18
TomatoesStart indoors · Feb 28 – Mar 14
TomatoesTransplant · May 2 – May 16
Peppers, eggplantStart indoors · Feb 14 – Feb 28
Peppers, eggplantTransplant · May 9 – May 23
BeansSow outdoors · May 2 – May 16
Sweet cornSow outdoors · May 2 – May 16
Cucumbers, squashSow outdoors · May 2 – May 16
Fall lettuce, spinachSow outdoors · Aug 17 – Aug 31
GarlicPlant cloves · Sep 28 – Nov 2
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 25) and first fall frost (Oct 12) 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 50837 came on Mar 18 — 15 days earlier than the 1991–2020 average (Apr 2).

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).

Soil in Bridgewater, IA

The soil mapped at the center of ZIP 50837 is Lamoni — silty clay loam, somewhat poorly drained.

TextureSilty clay loamholds water and nutrients; slow to drain and warm up
pH6.4slightly acidic; most vegetables like 6.0–7.0
DrainageSomewhat poorly drainedconsider raised beds
Organic matter3%moderate
Hydrologic groupDwater soaks in very slowly
Farmland classFarmland of statewide importanceUSDA classification

Map unit: Lamoni silty clay loam, 9 to 14 percent slopes, eroded.

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 50837; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Bridgewater, IA

Summer high84 °Faverage high, July
Winter low11 °Faverage low, January
Hot days19days a year at 90 °F or more
Freezing nights138nights a year at 32 °F or less
Growing degree days3,164base 50 °F — the season’s usable heat
Longest day15 h 09 mindaylight on June 21
Shortest day9 h 12 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation36.5 inper year, rain and melted snow

Average high and low, by month

0°10°20°30°40°50°60°70°80°90°32 °FJanuary: average high 30 °F, low 11 °F 30°11° JanFebruary: average high 35 °F, low 15 °F 35°15° FebMarch: average high 48 °F, low 27 °F 48°27° MarApril: average high 61 °F, low 38 °F 61°38° AprMay: average high 71 °F, low 50 °F 71°50° MayJune: average high 80 °F, low 60 °F 80°60° JunJuly: average high 84 °F, low 64 °F 84°64° JulAugust: average high 83 °F, low 62 °F 83°62° AugSeptember: average high 76 °F, low 53 °F 76°53° SepOctober: average high 64 °F, low 41 °F 64°41° OctNovember: average high 48 °F, low 28 °F 48°28° NovDecember: average high 34 °F, low 17 °F 34°17° Dec

Precipitation by month inches

0″1″2″3″4″5″6″January: 0.82 in precipitation 0.8 JanFebruary: 1.22 in precipitation 1.2 FebMarch: 2.02 in precipitation 2.0 MarApril: 3.60 in precipitation 3.6 AprMay: 5.46 in precipitation 5.5 MayJune: 5.11 in precipitation 5.1 JunJuly: 4.19 in precipitation 4.2 JulAugust: 4.37 in precipitation 4.4 AugSeptember: 3.73 in precipitation 3.7 SepOctober: 2.91 in precipitation 2.9 OctNovember: 1.71 in precipitation 1.7 NovDecember: 1.34 in precipitation 1.3 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Greenfield, IA (14 mi away); precipitation: Massena, IA (4 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 5b.

508535b
Massena, IA · 4 mi
508465b
Fontanelle, IA · 9 mi
508435b
Cumberland, IA · 10 mi
508595b
Prescott, IA · 12 mi
508395b
Carbon, IA · 14 mi
502745b
Wiota, IA · 14 mi
500205b
Anita, IA · 15 mi
508585b
Orient, IA · 15 mi

Iowa planting zones →

Questions about 50837

What planting zone is ZIP code 50837?

ZIP code 50837 (Bridgewater, 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 Bridgewater, IA?

The median last spring frost (32 °F) near 50837 is April 25; after May 7 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Greenfield station.

When is the first frost in Bridgewater, IA?

The median first fall frost near 50837 is October 12, giving a median frost-free growing season of 170 days.

When should I plant tomatoes in 50837?

Start tomato seeds indoors around Feb 28 – Mar 14 and set transplants outside around May 2 – May 16, one to three weeks after the median last frost.

How much rain and snow does 50837 get?

About 36.5 inches of precipitation a year (NOAA 1991–2020 normals, Massena station).

How hot do summers get in Bridgewater, IA?

The average high peaks at 84 °F in July, with about 19 days a year at 90 °F or more.

What kind of soil does 50837 have?

The USDA soil survey maps Lamoni at the center of ZIP 50837: silty clay loam, somewhat poorly drained, pH about 6.4 (slightly acidic).

Did spring come early in Bridgewater, IA in 2026?

Spring leaf-out near 50837 came on Mar 18 in 2026, 15 days earlier than the 1991–2020 average (Apr 2), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Bridgewater, IA?

Long-day onions: the longest day near 50837 is 15 h 09 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 50837 change?

Yes. The 2012 USDA map put 50837 in zone 5a; the 2023 map puts it in zone 5b. The newer map uses 1991–2020 data and more weather stations.