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

Planting zone for 57473 — Seneca, SD

ZIP code 57473 (Seneca, Faulk County) is in USDA zone 4b: the coldest winter night averages −25 to −20 °F. The median last spring frost is May 14 and the first fall frost September 29.

Where ZIP 57473 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.

Zone4b−25 to −20 °F
Coldest night−31.7 to −28.9 °C
Last frostMay 14
First frostSep 29
2012 zone4b

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 4b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Seneca, SD…

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 Seneca, SD

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMay 14median — 50% chance of a later frost
Safe for tender plantsMay 25only 10% chance of frost after
First fall frostSeptember 29median — 10% chance by Sep 16
Growing season138 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 4 and returns around October 7.

From the NOAA station Highmore 23 N, SD — 10 miles away, elevation 1,870 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 57473

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Apr 2 – Apr 16
SpinachSow outdoors · Apr 2 – Apr 23
Broccoli, cabbageStart indoors · Mar 5 – Mar 19
Broccoli, cabbageTransplant · Apr 23 – May 7
Onion setsPlant outdoors · Apr 16 – Apr 30
PotatoesPlant outdoors · Apr 23 – May 7
LettuceSow outdoors · Apr 16 – Apr 30
Carrots, beetsSow outdoors · Apr 23 – May 7
TomatoesStart indoors · Mar 19 – Apr 2
TomatoesTransplant · May 21 – Jun 4
Peppers, eggplantStart indoors · Mar 5 – Mar 19
Peppers, eggplantTransplant · May 28 – Jun 11
BeansSow outdoors · May 21 – Jun 4
Sweet cornSow outdoors · May 21 – Jun 4
Cucumbers, squashSow outdoors · May 21 – Jun 4
Fall lettuce, spinachSow outdoors · Aug 4 – Aug 18
GarlicPlant cloves · Sep 15 – Oct 20
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 14) and first fall frost (Sep 29) 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 57473 came on Mar 29 — 16 days earlier than the 1991–2020 average (Apr 14).

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 4b in South Dakota

430 plants native to the lower 48 states, recorded in South Dakota, and rated by the USDA to survive −25 °F or colder — the bottom of zone 4b. Each links to its USDA PLANTS profile.

Trees 23

American basswood100 ft · blooms late spring · low shade tolerance · to −46 °FAmerican elm120 ft · blooms early spring · medium shade tolerance · to −46 °Fbalsam poplar80 ft · blooms late spring · high shade tolerance · to −79 °Fblack locust60 ft · blooms spring · high shade tolerance · to −37 °Fblack maple100 ft · blooms late spring · low shade tolerance · to −47 °Fblack walnut100 ft · blooms late spring · high shade tolerance · to −28 °F

Shrubs 65

alderleaf buckthorn3 ft · blooms late spring · low shade tolerance · to −33 °Falderleaf 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 °Fbeaked hazelnut15 ft · blooms early spring · low shade tolerance · to −47 °F

Wildflowers & perennials 191

alkali buttercup1 ft · blooms late spring · low shade tolerance · to −38 °Falpine bistort1 ft · blooms mid spring · high shade tolerance · to −38 °Falpine mountainsorrel1 ft · blooms mid summer · medium shade tolerance · to −43 °Falpine sweetvetch2 ft · blooms early summer · high shade tolerance · to −62 °FAmerican eelgrass1 ft · blooms mid summer · high shade tolerance · to −33 °FAmerican licorice4 ft · blooms late spring · medium shade tolerance · to −38 °F

Grasses 138

Alaska oniongrass3 ft · blooms mid spring · low shade tolerance · to −33 °Falkali cordgrass3 ft · blooms late summer · high shade tolerance · to −38 °Falkali sacaton3 ft · blooms mid summer · high shade tolerance · to −38 °Falpine timothy1.4 ft · blooms late spring · medium shade tolerance · to −43 °Farctic brome3 ft · blooms early summer · low shade tolerance · to −33 °Fawlfruit sedge4 ft · blooms mid spring · low shade tolerance · to −38 °F

Vines 5

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 °FVirginia creeper1 ft · blooms late spring · medium shade tolerance · to −28 °Fwestern white clematis1 ft · blooms mid summer · medium shade tolerance · to −38 °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 Seneca, SD.

Soil in Seneca, SD

The soil mapped at the center of ZIP 57473 is Williams — loam, well drained.

TextureLoama good balance for most vegetables
pH7.2neutral; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter4%moderate
Hydrologic groupCwater soaks in slowly
Farmland classFarmland of statewide importanceUSDA classification

Map unit: Williams-Bowbells-Tonka complex, 0 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 57473; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Seneca, SD

Summer high85 °Faverage high, July
Winter low5 °Faverage low, January
Hot days25days a year at 90 °F or more
Freezing nights177nights a year at 32 °F or less
Growing degree days2,408base 50 °F — the season’s usable heat
Longest day15 h 37 mindaylight on June 21
Shortest day8 h 46 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation21.1 inper year, rain and melted snow
Snowfall43 inper year

Average high and low, by month

−10°0°10°20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 24 °F, low 5 °F 24°5° JanFebruary: average high 30 °F, low 10 °F 30°10° FebMarch: average high 42 °F, low 20 °F 42°20° MarApril: average high 57 °F, low 30 °F 57°30° AprMay: average high 68 °F, low 42 °F 68°42° MayJune: average high 78 °F, low 53 °F 78°53° JunJuly: average high 85 °F, low 58 °F 85°58° JulAugust: average high 84 °F, low 56 °F 84°56° AugSeptember: average high 75 °F, low 47 °F 75°47° SepOctober: average high 58 °F, low 34 °F 58°34° OctNovember: average high 42 °F, low 20 °F 42°20° NovDecember: average high 29 °F, low 9 °F 29°9° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″4″January: 0.51 in precipitation, 6.6 in snowfall 0.5❄7 JanFebruary: 0.80 in precipitation, 10.9 in snowfall 0.8❄11 FebMarch: 1.07 in precipitation, 6.2 in snowfall 1.1❄6 MarApril: 2.05 in precipitation, 5.9 in snowfall 2.0❄6 AprMay: 2.82 in precipitation 2.8 MayJune: 3.76 in precipitation 3.8 JunJuly: 2.32 in precipitation 2.3 JulAugust: 2.51 in precipitation 2.5 AugSeptember: 2.15 in precipitation 2.1 SepOctober: 1.87 in precipitation, 1.2 in snowfall 1.9❄1 OctNovember: 0.65 in precipitation, 2.8 in snowfall 0.7❄3 NovDecember: 0.58 in precipitation, 9.3 in snowfall 0.6❄9 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Highmore 23 N, SD (10 mi away); precipitation: Seneca, SD (5 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 4b.

574554b
Lebanon, SD · 10 mi
574664b
Onaka, SD · 14 mi
574384b
Faulkton, SD · 16 mi
574754b
Tolstoy, SD · 18 mi
574674b
Orient, SD · 18 mi
574504b
Hoven, SD · 23 mi
573454b
Highmore, SD · 29 mi
574704b
Rockham, SD · 29 mi

South Dakota planting zones →

Questions about 57473

What planting zone is ZIP code 57473?

ZIP code 57473 (Seneca, SD) is in USDA hardiness zone 4b on the 2023 map: the coldest night of an average winter reaches −25 to −20 °F (−31.7 to −28.9 °C).

When is the last frost in Seneca, SD?

The median last spring frost (32 °F) near 57473 is May 14; after May 25 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Highmore 23 N station.

When is the first frost in Seneca, SD?

The median first fall frost near 57473 is September 29, giving a median frost-free growing season of 138 days.

When should I plant tomatoes in 57473?

Start tomato seeds indoors around Mar 19 – Apr 2 and set transplants outside around May 21 – Jun 4, one to three weeks after the median last frost.

How much rain and snow does 57473 get?

About 21.1 inches of precipitation a year and 43 inches of snowfall (NOAA 1991–2020 normals, Seneca station).

How hot do summers get in Seneca, SD?

The average high peaks at 85 °F in July, with about 25 days a year at 90 °F or more.

What kind of soil does 57473 have?

The USDA soil survey maps Williams at the center of ZIP 57473: loam, well drained, pH about 7.2 (neutral).

Did spring come early in Seneca, SD in 2026?

Spring leaf-out near 57473 came on Mar 29 in 2026, 16 days earlier than the 1991–2020 average (Apr 14), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Seneca, SD?

Long-day onions: the longest day near 57473 is 15 h 37 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).