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

Planting zone for 45674 — Rio Grande, OH

ZIP code 45674 (Rio Grande, Gallia County) is in USDA zone 6b: the coldest winter night averages −5 to 0 °F. The median last spring frost is April 18 and the first fall frost October 28.

Where ZIP 45674 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 18
First frostOct 28
2012 zone6b

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 6b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Rio Grande, 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 Rio Grande, OH

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 18median — 50% chance of a later frost
Safe for tender plantsMay 4only 10% chance of frost after
First fall frostOctober 28median — 10% chance by Oct 15
Growing season192 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 4 and returns around November 5.

From the NOAA station Gallipolis, OH — 11 miles away, elevation 577 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 45674

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 7 – Mar 21
SpinachSow outdoors · Mar 7 – Mar 28
Broccoli, cabbageStart indoors · Feb 7 – Feb 21
Broccoli, cabbageTransplant · Mar 28 – Apr 11
Onion setsPlant outdoors · Mar 21 – Apr 4
PotatoesPlant outdoors · Mar 28 – Apr 11
LettuceSow outdoors · Mar 21 – Apr 4
Carrots, beetsSow outdoors · Mar 28 – Apr 11
TomatoesStart indoors · Feb 21 – Mar 7
TomatoesTransplant · Apr 25 – May 9
Peppers, eggplantStart indoors · Feb 7 – Feb 21
Peppers, eggplantTransplant · May 2 – May 16
BeansSow outdoors · Apr 25 – May 9
Sweet cornSow outdoors · Apr 25 – May 9
Cucumbers, squashSow outdoors · Apr 25 – May 9
Fall lettuce, spinachSow outdoors · Sep 2 – Sep 16
GarlicPlant cloves · Oct 14 – Nov 18
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 18) and first fall frost (Oct 28) 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 45674 came on Mar 8 — 9 days earlier than the 1991–2020 average (Mar 17).

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 6b in Ohio

570 plants native to the lower 48 states, recorded in Ohio, and rated by the USDA to survive −5 °F or colder — the bottom of zone 6b. Each links to its USDA PLANTS profile.

Trees 71

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 203

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 165

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 10

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 °Fgraybark grape50 ft · blooms late spring · medium shade tolerance · to −8 °Fheartleaf peppervine2 ft · blooms late spring · low shade tolerance · to −8 °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 Rio Grande, OH.

Soil in Rio Grande, OH

The soil mapped at the center of ZIP 45674 is Omulga — silt loam, moderately well drained.

TextureSilt loama good balance for most vegetables
pH5.9moderately acidic; most vegetables like 6.0–7.0
DrainageModerately well drainednatural drainage class
Organic matter1.25%low — add compost
Hydrologic groupCwater soaks in slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Omulga silt loam, 6 to 12 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 45674; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Rio Grande, OH

Summer high86 °Faverage high, July
Winter low23 °Faverage low, January
Hot days32days a year at 90 °F or more
Freezing nights103nights a year at 32 °F or less
Growing degree days3,803base 50 °F — the season’s usable heat
Longest day14 h 54 mindaylight on June 21
Shortest day9 h 26 mindaylight on December 21
Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully
Precipitation37.4 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 41 °F, low 23 °F 41°23° JanFebruary: average high 46 °F, low 25 °F 46°25° FebMarch: average high 55 °F, low 32 °F 55°32° MarApril: average high 67 °F, low 42 °F 67°42° AprMay: average high 75 °F, low 52 °F 75°52° MayJune: average high 83 °F, low 61 °F 83°61° JunJuly: average high 86 °F, low 66 °F 86°66° JulAugust: average high 86 °F, low 64 °F 86°64° AugSeptember: average high 80 °F, low 57 °F 80°57° SepOctober: average high 68 °F, low 45 °F 68°45° OctNovember: average high 56 °F, low 34 °F 56°34° NovDecember: average high 45 °F, low 28 °F 45°28° Dec

Precipitation by month inches

0″1″2″3″4″January: 3.29 in precipitation 3.3 JanFebruary: 2.51 in precipitation 2.5 FebMarch: 3.11 in precipitation 3.1 MarApril: 3.19 in precipitation 3.2 AprMay: 3.16 in precipitation 3.2 MayJune: 3.61 in precipitation 3.6 JunJuly: 3.35 in precipitation 3.4 JulAugust: 3.25 in precipitation 3.3 AugSeptember: 3.54 in precipitation 3.5 SepOctober: 2.46 in precipitation 2.5 OctNovember: 2.58 in precipitation 2.6 NovDecember: 3.35 in precipitation 3.4 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Gallipolis, OH (11 mi away); precipitation: Oak Hill 0.6 Ssw, OH (11 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

456856b
Thurman, OH · 6 mi
456146b
Bidwell, OH · 7 mi
456436b
Kerr, OH · 7 mi
456316b
Gallipolis, OH · 7 mi
456586b
Patriot, OH · 8 mi
456866b
Vinton, OH · 9 mi
456566b
Oak Hill, OH · 11 mi
456887a
Waterloo, OH · 13 mi

Ohio planting zones →

Questions about 45674

What planting zone is ZIP code 45674?

ZIP code 45674 (Rio Grande, OH) 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 Rio Grande, OH?

The median last spring frost (32 °F) near 45674 is April 18; after May 4 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Gallipolis station.

When is the first frost in Rio Grande, OH?

The median first fall frost near 45674 is October 28, giving a median frost-free growing season of 192 days.

When should I plant tomatoes in 45674?

Start tomato seeds indoors around Feb 21 – Mar 7 and set transplants outside around Apr 25 – May 9, one to three weeks after the median last frost.

How much rain and snow does 45674 get?

About 37.4 inches of precipitation a year (NOAA 1991–2020 normals, Oak Hill 0.6 Ssw station).

How hot do summers get in Rio Grande, OH?

The average high peaks at 86 °F in July, with about 32 days a year at 90 °F or more.

What kind of soil does 45674 have?

The USDA soil survey maps Omulga at the center of ZIP 45674: silt loam, moderately well drained, pH about 5.9 (moderately acidic).

Did spring come early in Rio Grande, OH in 2026?

Spring leaf-out near 45674 came on Mar 8 in 2026, 9 days earlier than the 1991–2020 average (Mar 17), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Rio Grande, OH?

Intermediate onions: the longest day near 45674 is 14 h 54 min, so day-neutral types bulb best; long-day varieties may not bulb fully.