Data: 2023 USDA zones (PRISM/OSU) · NOAA 1991–2020 normals · updated Oct 29, 2026

Planting zone for 84324 — Mantua, UT

ZIP code 84324 (Mantua, Box Elder County) is in USDA zone 6a: the coldest winter night averages −10 to −5 °F. The median last spring frost is May 5 and the first fall frost October 5.

Where ZIP 84324 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.

Zone6a−10 to −5 °F

Coldest night−23.3 to −20.6 °C

Last frostMay 5

First frostOct 5

2012 zone6a

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 6a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Mantua, UT…

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 Mantua, UT

JanFebMarAprMayJunJulAugSepOctNovDec

Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free

Last spring frostMay 5median — 50% chance of a later frost

Safe for tender plantsMay 29only 10% chance of frost after

First fall frostOctober 5median — 10% chance by Sep 20

Growing season150 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 18 and returns around October 17.

From the NOAA station Brigham City Waste Plt, UT — 6 miles away, elevation 4,239 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 84324

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Mar 24 – Apr 7

SpinachSow outdoors · Mar 24 – Apr 14

Broccoli, cabbageStart indoors · Feb 24 – Mar 10

Broccoli, cabbageTransplant · Apr 14 – Apr 28

Onion setsPlant outdoors · Apr 7 – Apr 21

PotatoesPlant outdoors · Apr 14 – Apr 28

LettuceSow outdoors · Apr 7 – Apr 21

Carrots, beetsSow outdoors · Apr 14 – Apr 28

TomatoesStart indoors · Mar 10 – Mar 24

TomatoesTransplant · May 12 – May 26

Peppers, eggplantStart indoors · Feb 24 – Mar 10

Peppers, eggplantTransplant · May 19 – Jun 2

BeansSow outdoors · May 12 – May 26

Sweet cornSow outdoors · May 12 – May 26

Cucumbers, squashSow outdoors · May 12 – May 26

Fall lettuce, spinachSow outdoors · Aug 10 – Aug 24

GarlicPlant cloves · Sep 21 – Oct 26

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 5) and first fall frost (Oct 5) 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 84324 came on Mar 20 — 25 days earlier than the 1991–2020 average (Apr 14).

average
Apr 142026
Mar 20

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 6a in Utah

546 plants native to the lower 48 states, recorded in Utah, and rated by the USDA to survive −10 °F or colder — the bottom of zone 6a. Each links to its USDA PLANTS profile.

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 Mantua, UT.

Soil in Mantua, UT

The soil mapped at the center of ZIP 84324 is Kilburn — gravelly loam, somewhat excessively drained.

TextureGravelly loama good balance for most vegetables

pH6.7neutral; most vegetables like 6.0–7.0

DrainageSomewhat excessively drainednatural drainage class

Organic matter3.5%moderate

Hydrologic groupBwater soaks in moderately

Farmland classPrime farmland if irrigatedUSDA classification

Map unit: Kilburn gravelly loam, 1 to 3 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 84324; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Mantua, UT

Summer high91 °Faverage high, July

Winter low18 °Faverage low, January

Hot days45days a year at 90 °F or more

Freezing nights149nights a year at 32 °F or less

Growing degree days2,761base 50 °F — the season’s usable heat

Longest day15 h 11 mindaylight on June 21

Shortest day9 h 10 mindaylight on December 21

Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)

Precipitation23 inper year, rain and melted snow

Average high and low, by month

Precipitation by month inches

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Brigham City Waste Plt, UT (6 mi away); precipitation: Brigham City 1.2 N, UT (4 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

843286a

Paradise, UT · 6 mi

843026b

Brigham City, UT · 8 mi

843396a

Wellsville, UT · 9 mi

Bear River City, UT · 13 mi

843146b

Honeyville, UT · 13 mi

843407a

Willard, UT · 14 mi

Utah planting zones →

Questions about 84324

What planting zone is ZIP code 84324?

ZIP code 84324 (Mantua, UT) is in USDA hardiness zone 6a on the 2023 map: the coldest night of an average winter reaches −10 to −5 °F (−23.3 to −20.6 °C).

When is the last frost in Mantua, UT?

The median last spring frost (32 °F) near 84324 is May 5; after May 29 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Brigham City Waste Plt station.

When is the first frost in Mantua, UT?

The median first fall frost near 84324 is October 5, giving a median frost-free growing season of 150 days.

When should I plant tomatoes in 84324?

Start tomato seeds indoors around Mar 10 – Mar 24 and set transplants outside around May 12 – May 26, one to three weeks after the median last frost.

How much rain and snow does 84324 get?

About 23 inches of precipitation a year (NOAA 1991–2020 normals, Brigham City 1.2 N station).

How hot do summers get in Mantua, UT?

The average high peaks at 91 °F in July, with about 45 days a year at 90 °F or more.

What kind of soil does 84324 have?

The USDA soil survey maps Kilburn at the center of ZIP 84324: gravelly loam, somewhat excessively drained, pH about 6.7 (neutral).

Did spring come early in Mantua, UT in 2026?

Spring leaf-out near 84324 came on Mar 20 in 2026, 25 days earlier than the 1991–2020 average (Apr 14), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Mantua, UT?

Long-day onions: the longest day near 84324 is 15 h 11 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).