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

Planting zone for 43550 — Okolona, OH

ZIP code 43550 (Okolona, Henry County) is in USDA zone 6a: the coldest winter night averages −10 to −5 °F. The median last spring frost is April 23 and the first fall frost October 24.

Where ZIP 43550 is

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 frostApr 23
First frostOct 24
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 Okolona, OH…

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 Okolona, OH

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 23median — 50% chance of a later frost
Safe for tender plantsMay 9only 10% chance of frost after
First fall frostOctober 24median — 10% chance by Oct 10
Growing season183 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 11 and returns around November 4.

From the NOAA station Napoleon 1sw, OH — 4 miles away, elevation 669 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 43550

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 12 – Mar 26
SpinachSow outdoors · Mar 12 – Apr 2
Broccoli, cabbageStart indoors · Feb 12 – Feb 26
Broccoli, cabbageTransplant · Apr 2 – Apr 16
Onion setsPlant outdoors · Mar 26 – Apr 9
PotatoesPlant outdoors · Apr 2 – Apr 16
LettuceSow outdoors · Mar 26 – Apr 9
Carrots, beetsSow outdoors · Apr 2 – Apr 16
TomatoesStart indoors · Feb 26 – Mar 12
TomatoesTransplant · Apr 30 – May 14
Peppers, eggplantStart indoors · Feb 12 – Feb 26
Peppers, eggplantTransplant · May 7 – May 21
BeansSow outdoors · Apr 30 – May 14
Sweet cornSow outdoors · Apr 30 – May 14
Cucumbers, squashSow outdoors · Apr 30 – May 14
Fall lettuce, spinachSow outdoors · Aug 29 – Sep 12
GarlicPlant cloves · Oct 10 – Nov 14
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 23) and first fall frost (Oct 24) 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 43550 came on Mar 21 — 15 days earlier than the 1991–2020 average (Apr 5).

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 Ohio

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

Trees 70

American basswood100 ft · blooms late spring · low shade tolerance · to −46 °FAmerican beech80 ft · blooms mid spring · low shade tolerance · to −44 °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 °F

Shrubs 109

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 holly40 ft · blooms mid spring · low shade tolerance · to −20 °F

Wildflowers & perennials 202

American bur-reed3 ft · blooms indeterminate · medium shade tolerance · to −33 °FAmerican eelgrass1 ft · blooms mid summer · high shade tolerance · to −33 °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 °FAmerican vetch1.3 ft · blooms late spring · high shade tolerance · to −38 °F

Grasses 164

American beachgrass2.5 ft · blooms spring · high shade tolerance · to −28 °Farctic brome3 ft · blooms early summer · low shade tolerance · to −33 °Fawlfruit sedge4 ft · blooms mid spring · low shade tolerance · to −38 °Fbeaked spikerush3 ft · blooms late spring · high shade tolerance · to −28 °FBebb's sedge3 ft · blooms late spring · low shade tolerance · to −38 °FBicknell's sedge3 ft · blooms late spring · low shade tolerance · to −38 °F

Vines 8

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 creeper2 ft · blooms summer · high shade tolerance · to −13 °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 Okolona, OH.

Soil in Okolona, OH

The soil mapped at the center of ZIP 43550 is Lucas — silty clay, moderately well drained.

TextureSilty clayholds water and nutrients; slow to drain and warm up
pH5.7moderately acidic; most vegetables like 6.0–7.0
DrainageModerately well drainednatural drainage class
Organic matter1.1%low — add compost
Hydrologic groupDwater soaks in very slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Lucas silty clay, 6 to 12 percent slopes, severely 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 43550; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Okolona, OH

Summer high85 °Faverage high, July
Winter low18 °Faverage low, January
Hot days26days a year at 90 °F or more
Freezing nights121nights a year at 32 °F or less
Growing degree days3,206base 50 °F — the season’s usable heat
Longest day15 h 10 mindaylight on June 21
Shortest day9 h 11 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation36.6 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 33 °F, low 18 °F 33°18° JanFebruary: average high 36 °F, low 20 °F 36°20° FebMarch: average high 47 °F, low 27 °F 47°27° MarApril: average high 60 °F, low 38 °F 60°38° AprMay: average high 71 °F, low 50 °F 71°50° MayJune: average high 81 °F, low 61 °F 81°61° JunJuly: average high 85 °F, low 64 °F 85°64° JulAugust: average high 83 °F, low 62 °F 83°62° AugSeptember: average high 77 °F, low 54 °F 77°54° SepOctober: average high 64 °F, low 43 °F 64°43° OctNovember: average high 50 °F, low 32 °F 50°32° NovDecember: average high 38 °F, low 24 °F 38°24° Dec

Precipitation by month inches

0″1″2″3″4″5″January: 2.52 in precipitation 2.5 JanFebruary: 2.22 in precipitation 2.2 FebMarch: 2.42 in precipitation 2.4 MarApril: 3.56 in precipitation 3.6 AprMay: 4.14 in precipitation 4.1 MayJune: 3.89 in precipitation 3.9 JunJuly: 3.65 in precipitation 3.6 JulAugust: 3.54 in precipitation 3.5 AugSeptember: 2.97 in precipitation 3.0 SepOctober: 2.64 in precipitation 2.6 OctNovember: 2.74 in precipitation 2.7 NovDecember: 2.33 in precipitation 2.3 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Napoleon 1sw, OH (4 mi away); precipitation: Napoleon 1sw, OH (4 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 6a.

435456a
Napoleon, OH · 5 mi
435356a
Malinta, OH · 5 mi
435236a
Grelton, OH · 6 mi
435276a
Holgate, OH · 6 mi
435246a
Hamler, OH · 8 mi
435306a
Jewell, OH · 9 mi
435346a
Mc Clure, OH · 10 mi
435486a
New Bavaria, OH · 10 mi

Ohio planting zones →

Questions about 43550

What planting zone is ZIP code 43550?

ZIP code 43550 (Okolona, OH) 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 Okolona, OH?

The median last spring frost (32 °F) near 43550 is April 23; after May 9 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Napoleon 1sw station.

When is the first frost in Okolona, OH?

The median first fall frost near 43550 is October 24, giving a median frost-free growing season of 183 days.

When should I plant tomatoes in 43550?

Start tomato seeds indoors around Feb 26 – Mar 12 and set transplants outside around Apr 30 – May 14, one to three weeks after the median last frost.

How much rain and snow does 43550 get?

About 36.6 inches of precipitation a year (NOAA 1991–2020 normals, Napoleon 1sw station).

How hot do summers get in Okolona, OH?

The average high peaks at 85 °F in July, with about 26 days a year at 90 °F or more.

What kind of soil does 43550 have?

The USDA soil survey maps Lucas at the center of ZIP 43550: silty clay, moderately well drained, pH about 5.7 (moderately acidic).

Did spring come early in Okolona, OH in 2026?

Spring leaf-out near 43550 came on Mar 21 in 2026, 15 days earlier than the 1991–2020 average (Apr 5), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Okolona, OH?

Long-day onions: the longest day near 43550 is 15 h 10 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).