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

Planting zone for 68860 — Oconto, NE

ZIP code 68860 (Oconto, Custer County) is in USDA zone 5a: the coldest winter night averages −20 to −15 °F. The median last spring frost is May 10 and the first fall frost October 1.

Where ZIP 68860 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 frostMay 10
First frostOct 1
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 Oconto, NE…

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 Oconto, NE

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 22only 10% chance of frost after
First fall frostOctober 1median — 10% chance by Sep 18
Growing season145 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 30 and returns around October 9.

From the NOAA station Oconto, NE — 2 miles away, elevation 2,579 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 68860

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 68860 came on Mar 8 — 23 days earlier than the 1991–2020 average (Mar 31).

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 Nebraska

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

Trees 31

American basswood100 ft · blooms late spring · low shade tolerance · to −46 °FAmerican elm120 ft · blooms early spring · medium shade tolerance · to −46 °FAmerican sycamore100 ft · blooms spring · medium shade tolerance · to −34 °Fbitternut hickory75 ft · blooms mid spring · high shade tolerance · to −47 °Fblack locust60 ft · blooms spring · high shade tolerance · to −37 °Fblack oak80 ft · blooms early spring · medium shade tolerance · to −30 °F

Shrubs 55

alderleaf mountain mahogany15 ft · blooms late spring · medium shade tolerance · to −41 °FAmerican black currant3 ft · blooms early spring · to −46 °FAmerican hazelnut10 ft · blooms spring · medium shade tolerance · to −33 °FAmerican plum24 ft · blooms mid spring · high shade tolerance · to −38 °Fantelope bitterbrush6 ft · blooms early spring · medium shade tolerance · to −36 °Fbig sagebrush4 ft · blooms mid summer · high shade tolerance · to −43 °F

Wildflowers & perennials 184

alkali buttercup1 ft · blooms late spring · low shade tolerance · to −38 °Falpine sweetvetch2 ft · blooms early summer · high shade tolerance · to −62 °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 °FAmerican speedwell0.8 ft · blooms mid summer · low shade tolerance · to −38 °F

Grasses 129

alkali cordgrass3 ft · blooms late summer · high shade tolerance · to −38 °Falkali sacaton3 ft · blooms mid summer · high shade tolerance · to −38 °Fawlfruit sedge4 ft · blooms mid spring · low shade tolerance · to −38 °Fbasin wildrye5 ft · blooms early spring · high shade tolerance · to −43 °Fbeaked spikerush3 ft · blooms late spring · high shade tolerance · to −28 °FBebb's sedge3 ft · blooms late spring · low shade tolerance · to −38 °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 °FVirginia creeper1 ft · blooms late spring · medium shade tolerance · to −28 °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 Oconto, NE.

Soil in Oconto, NE

The soil mapped at the center of ZIP 68860 is Uly — silt loam, well drained.

TextureSilt loama good balance for most vegetables
pH6.8neutral; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter3%moderate
Hydrologic groupBwater soaks in moderately
Farmland classNot prime farmlandUSDA classification

Map unit: Uly-Coly silt loams, 17 to 30 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 68860; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Oconto, NE

Summer high87 °Faverage high, July
Winter low13 °Faverage low, January
Hot days32days a year at 90 °F or more
Freezing nights165nights a year at 32 °F or less
Growing degree days2,973base 50 °F — the season’s usable heat
Longest day15 h 08 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)
Precipitation23.5 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 38 °F, low 13 °F 38°13° JanFebruary: average high 41 °F, low 15 °F 41°15° FebMarch: average high 53 °F, low 24 °F 53°24° MarApril: average high 63 °F, low 34 °F 63°34° AprMay: average high 72 °F, low 45 °F 72°45° MayJune: average high 82 °F, low 57 °F 82°57° JunJuly: average high 87 °F, low 61 °F 87°61° JulAugust: average high 85 °F, low 59 °F 85°59° AugSeptember: average high 79 °F, low 49 °F 79°49° SepOctober: average high 65 °F, low 36 °F 65°36° OctNovember: average high 51 °F, low 23 °F 51°23° NovDecember: average high 40 °F, low 14 °F 40°14° Dec

Precipitation by month inches

0″1″2″3″4″5″January: 0.34 in precipitation 0.3 JanFebruary: 0.36 in precipitation 0.4 FebMarch: 1.04 in precipitation 1.0 MarApril: 2.57 in precipitation 2.6 AprMay: 4.11 in precipitation 4.1 MayJune: 3.62 in precipitation 3.6 JunJuly: 3.11 in precipitation 3.1 JulAugust: 2.96 in precipitation 3.0 AugSeptember: 2.27 in precipitation 2.3 SepOctober: 1.91 in precipitation 1.9 OctNovember: 0.78 in precipitation 0.8 NovDecember: 0.41 in precipitation 0.4 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Oconto, NE (2 mi away); precipitation: Eddyville 11.4 N, NE (10 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

688345b
Eddyville, NE · 11 mi
688255b
Callaway, NE · 13 mi
688785b
Sumner, NE · 18 mi
691305b
Cozad, NE · 19 mi
688225b
Broken Bow, NE · 20 mi
688505b
Lexington, NE · 21 mi
691715b
Willow Island, NE · 22 mi
691385b
Gothenburg, NE · 22 mi

Nebraska planting zones →

Questions about 68860

What planting zone is ZIP code 68860?

ZIP code 68860 (Oconto, NE) 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 Oconto, NE?

The median last spring frost (32 °F) near 68860 is May 10; after May 22 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Oconto station.

When is the first frost in Oconto, NE?

The median first fall frost near 68860 is October 1, giving a median frost-free growing season of 145 days.

When should I plant tomatoes in 68860?

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 68860 get?

About 23.5 inches of precipitation a year (NOAA 1991–2020 normals, Eddyville 11.4 N station).

How hot do summers get in Oconto, NE?

The average high peaks at 87 °F in July, with about 32 days a year at 90 °F or more.

What kind of soil does 68860 have?

The USDA soil survey maps Uly at the center of ZIP 68860: silt loam, well drained, pH about 6.8 (neutral).

Did spring come early in Oconto, NE in 2026?

Spring leaf-out near 68860 came on Mar 8 in 2026, 23 days earlier than the 1991–2020 average (Mar 31), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Oconto, NE?

Long-day onions: the longest day near 68860 is 15 h 08 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).