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

Planting zone for 65256 — Harrisburg, MO

ZIP code 65256 (Harrisburg, Boone County) is in USDA zone 6b: the coldest winter night averages −5 to 0 °F. The median last spring frost is April 5 and the first fall frost October 31.

Where ZIP 65256 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.

Zone6b−5 to 0 °F
Coldest night−20.6 to −17.8 °C
Last frostApr 5
First frostOct 31
2012 zone6a

Was 6a 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 6b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Harrisburg, MO…

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 Harrisburg, MO

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 5median — 50% chance of a later frost
Safe for tender plantsApril 21only 10% chance of frost after
First fall frostOctober 31median — 10% chance by Oct 17
Growing season207 daysfrost-free, median

A hard freeze (28 °F) usually ends around March 26 and returns around November 9.

From the NOAA station Columbia U Of M, MO — 14 miles away, elevation 771 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 65256

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Feb 22 – Mar 8
SpinachSow outdoors · Feb 22 – Mar 15
Broccoli, cabbageStart indoors · Jan 25 – Feb 8
Broccoli, cabbageTransplant · Mar 15 – Mar 29
Onion setsPlant outdoors · Mar 8 – Mar 22
PotatoesPlant outdoors · Mar 15 – Mar 29
LettuceSow outdoors · Mar 8 – Mar 22
Carrots, beetsSow outdoors · Mar 15 – Mar 29
TomatoesStart indoors · Feb 8 – Feb 22
TomatoesTransplant · Apr 12 – Apr 26
Peppers, eggplantStart indoors · Jan 25 – Feb 8
Peppers, eggplantTransplant · Apr 19 – May 3
BeansSow outdoors · Apr 12 – Apr 26
Sweet cornSow outdoors · Apr 12 – Apr 26
Cucumbers, squashSow outdoors · Apr 12 – Apr 26
Fall lettuce, spinachSow outdoors · Sep 5 – Sep 19
GarlicPlant cloves · Oct 17 – Nov 21
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 5) and first fall frost (Oct 31) 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 65256 came on Mar 3 — 15 days earlier than the 1991–2020 average (Mar 18).

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 Harrisburg, MO

The soil mapped at the center of ZIP 65256 is Armstrong — loam, somewhat poorly drained.

TextureLoama good balance for most vegetables
pH6.8neutral; most vegetables like 6.0–7.0
DrainageSomewhat poorly drainedconsider raised beds
Organic matter2%moderate
Hydrologic groupDwater soaks in very slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Armstrong loam, 5 to 9 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 65256; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Harrisburg, MO

Summer high89 °Faverage high, July
Winter low23 °Faverage low, January
Hot days41days a year at 90 °F or more
Freezing nights93nights a year at 32 °F or less
Growing degree days4,271base 50 °F — the season’s usable heat
Longest day14 h 55 mindaylight on June 21
Shortest day9 h 25 mindaylight on December 21
Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully
Precipitation43.4 inper year, rain and melted snow

Average high and low, by month

10°20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 39 °F, low 23 °F 39°23° JanFebruary: average high 45 °F, low 27 °F 45°27° FebMarch: average high 56 °F, low 36 °F 56°36° MarApril: average high 67 °F, low 46 °F 67°46° AprMay: average high 76 °F, low 56 °F 76°56° MayJune: average high 85 °F, low 65 °F 85°65° JunJuly: average high 89 °F, low 69 °F 89°69° JulAugust: average high 88 °F, low 67 °F 88°67° AugSeptember: average high 80 °F, low 59 °F 80°59° SepOctober: average high 68 °F, low 47 °F 68°47° OctNovember: average high 55 °F, low 37 °F 55°37° NovDecember: average high 44 °F, low 27 °F 44°27° Dec

Precipitation by month inches

0″1″2″3″4″5″January: 2.18 in precipitation 2.2 JanFebruary: 2.41 in precipitation 2.4 FebMarch: 3.37 in precipitation 3.4 MarApril: 4.58 in precipitation 4.6 AprMay: 4.92 in precipitation 4.9 MayJune: 4.97 in precipitation 5.0 JunJuly: 4.44 in precipitation 4.4 JulAugust: 3.76 in precipitation 3.8 AugSeptember: 4.05 in precipitation 4.0 SepOctober: 3.56 in precipitation 3.6 OctNovember: 3.06 in precipitation 3.1 NovDecember: 2.10 in precipitation 2.1 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Columbia U Of M, MO (14 mi away); precipitation: Harrisburg 5.9 Sse, MO (4 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 6b.

652056b
Columbia, MO · 8 mi
652846b
Sturgeon, MO · 9 mi
652796b
Rocheport, MO · 10 mi
652486b
Fayette, MO · 11 mi
652026b
Columbia, MO · 11 mi
652436b
Clark, MO · 12 mi
652576b
Higbee, MO · 12 mi
652556b
Hallsville, MO · 13 mi

Missouri planting zones →

Questions about 65256

What planting zone is ZIP code 65256?

ZIP code 65256 (Harrisburg, MO) is in USDA hardiness zone 6b on the 2023 map: the coldest night of an average winter reaches −5 to 0 °F (−20.6 to −17.8 °C).

When is the last frost in Harrisburg, MO?

The median last spring frost (32 °F) near 65256 is April 5; after April 21 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Columbia U Of M station.

When is the first frost in Harrisburg, MO?

The median first fall frost near 65256 is October 31, giving a median frost-free growing season of 207 days.

When should I plant tomatoes in 65256?

Start tomato seeds indoors around Feb 8 – Feb 22 and set transplants outside around Apr 12 – Apr 26, one to three weeks after the median last frost.

How much rain and snow does 65256 get?

About 43.4 inches of precipitation a year (NOAA 1991–2020 normals, Harrisburg 5.9 Sse station).

How hot do summers get in Harrisburg, MO?

The average high peaks at 89 °F in July, with about 41 days a year at 90 °F or more.

What kind of soil does 65256 have?

The USDA soil survey maps Armstrong at the center of ZIP 65256: loam, somewhat poorly drained, pH about 6.8 (neutral).

Did spring come early in Harrisburg, MO in 2026?

Spring leaf-out near 65256 came on Mar 3 in 2026, 15 days earlier than the 1991–2020 average (Mar 18), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Harrisburg, MO?

Intermediate onions: the longest day near 65256 is 14 h 55 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

Did the zone for 65256 change?

Yes. The 2012 USDA map put 65256 in zone 6a; the 2023 map puts it in zone 6b. The newer map uses 1991–2020 data and more weather stations.