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

Planting zone for 52228 — Fairfax, IA

ZIP code 52228 (Fairfax, Linn County) is in USDA zone 5a: the coldest winter night averages −20 to −15 °F. The median last spring frost is April 27 and the first fall frost October 11.

Where ZIP 52228 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.

Zone5a−20 to −15 °F
Coldest night−28.9 to −26.1 °C
Last frostApr 27
First frostOct 11
2012 zone5a

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 5a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Fairfax, 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 Fairfax, IA

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 27median — 50% chance of a later frost
Safe for tender plantsMay 11only 10% chance of frost after
First fall frostOctober 11median — 10% chance by Sep 25
Growing season165 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 16 and returns around October 21.

From the NOAA station Cedar Rapids Municipal Airport, IA — 4 miles away, elevation 869 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 52228

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 16 – Mar 30
SpinachSow outdoors · Mar 16 – Apr 6
Broccoli, cabbageStart indoors · Feb 16 – Mar 2
Broccoli, cabbageTransplant · Apr 6 – Apr 20
Onion setsPlant outdoors · Mar 30 – Apr 13
PotatoesPlant outdoors · Apr 6 – Apr 20
LettuceSow outdoors · Mar 30 – Apr 13
Carrots, beetsSow outdoors · Apr 6 – Apr 20
TomatoesStart indoors · Mar 2 – Mar 16
TomatoesTransplant · May 4 – May 18
Peppers, eggplantStart indoors · Feb 16 – Mar 2
Peppers, eggplantTransplant · May 11 – May 25
BeansSow outdoors · May 4 – May 18
Sweet cornSow outdoors · May 4 – May 18
Cucumbers, squashSow outdoors · May 4 – May 18
Fall lettuce, spinachSow outdoors · Aug 16 – Aug 30
GarlicPlant cloves · Sep 27 – Nov 1
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 27) and first fall frost (Oct 11) 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 52228 came on Mar 25 — 13 days earlier than the 1991–2020 average (Apr 7).

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 5a in Iowa

461 plants native to the lower 48 states, recorded in Iowa, and rated by the USDA to survive −20 °F or colder — the bottom of zone 5a. Each links to its USDA PLANTS profile.

Trees 46

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 185

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 133

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 Fairfax, IA.

Soil in Fairfax, IA

The soil mapped at the center of ZIP 52228 is Dinsdale — silty clay loam, moderately well drained.

TextureSilty clay loamholds water and nutrients; slow to drain and warm up
pH6.4slightly acidic; most vegetables like 6.0–7.0
DrainageModerately well drainednatural drainage class
Organic matter3.5%moderate
Hydrologic groupCwater soaks in slowly
Farmland classprime farmlandUSDA classification

Map unit: Dinsdale silty clay loam, 2 to 5 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 52228; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Fairfax, IA

Summer high83 °Faverage high, July
Winter low11 °Faverage low, January
Hot days12days a year at 90 °F or more
Freezing nights144nights a year at 32 °F or less
Growing degree days2,962base 50 °F — the season’s usable heat
Longest day15 h 14 mindaylight on June 21
Shortest day9 h 07 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation34.6 inper year, rain and melted snow
Snowfall27 inper year; 52 days with snow on the ground

Average high and low, by month

0°10°20°30°40°50°60°70°80°90°32 °FJanuary: average high 28 °F, low 11 °F 28°11° JanFebruary: average high 33 °F, low 16 °F 33°16° FebMarch: average high 46 °F, low 27 °F 46°27° MarApril: average high 60 °F, low 38 °F 60°38° AprMay: average high 71 °F, low 50 °F 71°50° MayJune: average high 80 °F, low 60 °F 80°60° JunJuly: average high 83 °F, low 63 °F 83°63° JulAugust: average high 81 °F, low 60 °F 81°60° AugSeptember: average high 75 °F, low 52 °F 75°52° SepOctober: average high 62 °F, low 40 °F 62°40° OctNovember: average high 46 °F, low 28 °F 46°28° NovDecember: average high 33 °F, low 17 °F 33°17° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″4″5″6″January: 0.93 in precipitation, 7.7 in snowfall 0.9❄8 JanFebruary: 0.86 in precipitation, 5.7 in snowfall 0.9❄6 FebMarch: 1.69 in precipitation, 3.7 in snowfall 1.7❄4 MarApril: 3.61 in precipitation, 0.8 in snowfall 3.6❄1 AprMay: 4.07 in precipitation 4.1 MayJune: 5.37 in precipitation 5.4 JunJuly: 4.61 in precipitation 4.6 JulAugust: 4.01 in precipitation 4.0 AugSeptember: 3.33 in precipitation 3.3 SepOctober: 2.89 in precipitation, 0.2 in snowfall 2.9 OctNovember: 1.95 in precipitation, 1.2 in snowfall 1.9❄1 NovDecember: 1.32 in precipitation, 7.9 in snowfall 1.3❄8 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Cedar Rapids Municipal Airport, IA (4 mi away); precipitation: Walford 2 Se, IA (3 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

2 of the 8 nearest ZIP codes are in a different zone — elevation and distance from water change winter lows quickly.

523515a
Walford, IA · 3 mi
524045a
Cedar Rapids, IA · 5 mi
523185a
Norway, IA · 6 mi
524055a
Cedar Rapids, IA · 6 mi
523385a
Swisher, IA · 7 mi
522065a
Atkins, IA · 8 mi
522035b
Amana, IA · 8 mi
522045b
Amana, IA · 8 mi

Iowa planting zones →

Questions about 52228

What planting zone is ZIP code 52228?

ZIP code 52228 (Fairfax, IA) is in USDA hardiness zone 5a on the 2023 map: the coldest night of an average winter reaches −20 to −15 °F (−28.9 to −26.1 °C).

When is the last frost in Fairfax, IA?

The median last spring frost (32 °F) near 52228 is April 27; after May 11 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Cedar Rapids Municipal Airport station.

When is the first frost in Fairfax, IA?

The median first fall frost near 52228 is October 11, giving a median frost-free growing season of 165 days.

When should I plant tomatoes in 52228?

Start tomato seeds indoors around Mar 2 – Mar 16 and set transplants outside around May 4 – May 18, one to three weeks after the median last frost.

How much rain and snow does 52228 get?

About 34.6 inches of precipitation a year and 27 inches of snowfall (NOAA 1991–2020 normals, Walford 2 Se station).

How hot do summers get in Fairfax, IA?

The average high peaks at 83 °F in July, with about 12 days a year at 90 °F or more.

What kind of soil does 52228 have?

The USDA soil survey maps Dinsdale at the center of ZIP 52228: silty clay loam, moderately well drained, pH about 6.4 (slightly acidic).

Did spring come early in Fairfax, IA in 2026?

Spring leaf-out near 52228 came on Mar 25 in 2026, 13 days earlier than the 1991–2020 average (Apr 7), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Fairfax, IA?

Long-day onions: the longest day near 52228 is 15 h 14 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).