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

Planting zone for 56721 — East Grand Forks, MN

ZIP code 56721 (East Grand Forks, Polk County) is in USDA zone 4a: the coldest winter night averages −30 to −25 °F. The median last spring frost is May 10 and the first fall frost October 1.

Where ZIP 56721 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.

Zone4a−30 to −25 °F
Coldest night−34.4 to −31.7 °C
Last frostMay 10
First frostOct 1
2012 zone4a

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 4a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for East Grand Forks, MN…

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 East Grand Forks, MN

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMay 10median — 50% chance of a later frost
Safe for tender plantsMay 24only 10% chance of frost after
First fall frostOctober 1median — 10% chance by Sep 20
Growing season144 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 30 and returns around October 12.

From the NOAA station Grand Forks Univ (NWS), ND — 7 miles away, elevation 830 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 56721

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 29 – Apr 12
SpinachSow outdoors · Mar 29 – Apr 19
Broccoli, cabbageStart indoors · Mar 1 – Mar 15
Broccoli, cabbageTransplant · Apr 19 – May 3
Onion setsPlant outdoors · Apr 12 – Apr 26
PotatoesPlant outdoors · Apr 19 – May 3
LettuceSow outdoors · Apr 12 – Apr 26
Carrots, beetsSow outdoors · Apr 19 – May 3
TomatoesStart indoors · Mar 15 – Mar 29
TomatoesTransplant · May 17 – May 31
Peppers, eggplantStart indoors · Mar 1 – Mar 15
Peppers, eggplantTransplant · May 24 – Jun 7
BeansSow outdoors · May 17 – May 31
Sweet cornSow outdoors · May 17 – May 31
Cucumbers, squashSow outdoors · May 17 – May 31
Fall lettuce, spinachSow outdoors · Aug 6 – Aug 20
GarlicPlant cloves · Sep 17 – Oct 22
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 10) and first fall frost (Oct 1) 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 56721 came on Apr 26 — about the same time as the 1991–2020 average (Apr 24).

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 4a in Minnesota

445 plants native to the lower 48 states, recorded in Minnesota, and rated by the USDA to survive −30 °F or colder — the bottom of zone 4a. Each links to its USDA PLANTS profile.

Trees 45

American basswood100 ft · blooms late spring · low shade tolerance · to −46 °FAmerican beech80 ft · blooms mid spring · low shade tolerance · to −44 °FAmerican elm120 ft · blooms early spring · medium shade tolerance · to −46 °Farborvitae50 ft · blooms mid spring · medium shade tolerance · to −33 °Fbalsam fir60 ft · blooms mid summer · low shade tolerance · to −43 °Fbalsam poplar80 ft · blooms late spring · high shade tolerance · to −79 °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 173

alkali buttercup1 ft · blooms late spring · low shade tolerance · to −38 °Falpine bistort1 ft · blooms mid spring · high 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 °F

Grasses 140

alkali cordgrass3 ft · blooms late summer · high shade tolerance · to −38 °Farctic brome3 ft · blooms early summer · low shade tolerance · to −33 °Fawlfruit sedge4 ft · blooms mid spring · low shade tolerance · to −38 °Fbasin wildrye5 ft · blooms early spring · high shade tolerance · to −43 °Fbeaked sedge4 ft · blooms late spring · low shade tolerance · to −38 °FBebb's sedge3 ft · blooms late spring · low shade tolerance · to −38 °F

Vines 3

American bittersweet15 ft · blooms spring · low shade tolerance · to −38 °Fdevil's darning needles15 ft · blooms mid summer · medium shade tolerance · to −38 °Friverbank grape45 ft · blooms late spring · medium 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 East Grand Forks, MN.

Soil in East Grand Forks, MN

The soil mapped at the center of ZIP 56721 is Glyndon — loam, moderately well drained.

TextureLoama good balance for most vegetables
pH7.9alkaline; most vegetables like 6.0–7.0
DrainageModerately well drainednatural drainage class
Organic matter4%moderate
Hydrologic groupCwater soaks in slowly
Farmland classprime farmlandUSDA classification

Map unit: Glyndon loam, dry, 2 to 6 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 56721; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in East Grand Forks, MN

Summer high80 °Faverage high, July
Winter low−1 °Faverage low, January
Hot days7days a year at 90 °F or more
Freezing nights179nights a year at 32 °F or less
Growing degree days2,193base 50 °F — the season’s usable heat
Longest day16 h 02 mindaylight on June 21
Shortest day8 h 22 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation22.8 inper year, rain and melted snow
Snowfall49 inper year; 108 days with snow on the ground

Average high and low, by month

−10°0°10°20°30°40°50°60°70°80°90°32 °FJanuary: average high 15 °F, low -1 °F 15°−1° JanFebruary: average high 20 °F, low 3 °F 20°3° FebMarch: average high 34 °F, low 17 °F 34°17° MarApril: average high 52 °F, low 31 °F 52°31° AprMay: average high 67 °F, low 44 °F 67°44° MayJune: average high 76 °F, low 55 °F 76°55° JunJuly: average high 80 °F, low 59 °F 80°59° JulAugust: average high 79 °F, low 57 °F 79°57° AugSeptember: average high 70 °F, low 47 °F 70°47° SepOctober: average high 53 °F, low 35 °F 53°35° OctNovember: average high 35 °F, low 20 °F 35°20° NovDecember: average high 21 °F, low 6 °F 21°6° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″4″5″January: 0.49 in precipitation, 9.5 in snowfall 0.5❄10 JanFebruary: 0.56 in precipitation, 8.2 in snowfall 0.6❄8 FebMarch: 0.91 in precipitation, 7.8 in snowfall 0.9❄8 MarApril: 1.19 in precipitation, 3 in snowfall 1.2❄3 AprMay: 2.99 in precipitation, 0.1 in snowfall 3.0 MayJune: 4.13 in precipitation 4.1 JunJuly: 3.55 in precipitation 3.5 JulAugust: 3.03 in precipitation 3.0 AugSeptember: 2.42 in precipitation 2.4 SepOctober: 2.00 in precipitation, 1.5 in snowfall 2.0❄2 OctNovember: 0.83 in precipitation, 5.1 in snowfall 0.8❄5 NovDecember: 0.73 in precipitation, 13.5 in snowfall 0.7❄14 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Grand Forks Univ (NWS), ND (7 mi away); precipitation: Grand Forks Univ (NWS), ND (7 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 4a.

582064a
Grand Forks, ND · 5 mi
582074a
Grand Forks, ND · 5 mi
582084a
Grand Forks, ND · 5 mi
582034a
Grand Forks, ND · 10 mi
582014a
Grand Forks, ND · 11 mi
567234a
Fisher, MN · 13 mi
567224a
Euclid, MN · 14 mi
582564a
Manvel, ND · 14 mi

Minnesota planting zones →

Questions about 56721

What planting zone is ZIP code 56721?

ZIP code 56721 (East Grand Forks, MN) is in USDA hardiness zone 4a on the 2023 map: the coldest night of an average winter reaches −30 to −25 °F (−34.4 to −31.7 °C).

When is the last frost in East Grand Forks, MN?

The median last spring frost (32 °F) near 56721 is May 10; after May 24 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Grand Forks Univ (NWS) station.

When is the first frost in East Grand Forks, MN?

The median first fall frost near 56721 is October 1, giving a median frost-free growing season of 144 days.

When should I plant tomatoes in 56721?

Start tomato seeds indoors around Mar 15 – Mar 29 and set transplants outside around May 17 – May 31, one to three weeks after the median last frost.

How much rain and snow does 56721 get?

About 22.8 inches of precipitation a year and 49 inches of snowfall (NOAA 1991–2020 normals, Grand Forks Univ (NWS) station).

How hot do summers get in East Grand Forks, MN?

The average high peaks at 80 °F in July, with about 7 days a year at 90 °F or more.

What kind of soil does 56721 have?

The USDA soil survey maps Glyndon at the center of ZIP 56721: loam, moderately well drained, pH about 7.9 (alkaline).

Did spring come early in East Grand Forks, MN in 2026?

Spring leaf-out near 56721 came on Apr 26 in 2026, about the same as the 1991–2020 average (Apr 24), according to the USA National Phenology Network Spring Index.

What kind of onions grow in East Grand Forks, MN?

Long-day onions: the longest day near 56721 is 16 h 02 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).