Data: 2023 USDA zones (PRISM/OSU) · NOAA 1991–2020 normals · updated Oct 29, 2026

Planting zone for 21711 — Big Pool, MD

ZIP code 21711 (Big Pool, Washington County) is in USDA zone 7a: the coldest winter night averages 0 to 5 °F. The median last spring frost is April 17 and the first fall frost October 23.

Where ZIP 21711 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.

Zone7a0 to 5 °F

Coldest night−17.8 to −15 °C

Last frostApr 17

First frostOct 23

2012 zone6b

Was 6b 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 7a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Big Pool, MD…

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 Big Pool, MD

JanFebMarAprMayJunJulAugSepOctNovDec

Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free

Last spring frostApril 17median — 50% chance of a later frost

Safe for tender plantsMay 1only 10% chance of frost after

First fall frostOctober 23median — 10% chance by Oct 8

Growing season187 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 5 and returns around November 1.

From the NOAA station Martinsburg 2, WV — 14 miles away, elevation 459 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 21711

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Mar 6 – Mar 20

SpinachSow outdoors · Mar 6 – Mar 27

Broccoli, cabbageStart indoors · Feb 6 – Feb 20

Broccoli, cabbageTransplant · Mar 27 – Apr 10

Onion setsPlant outdoors · Mar 20 – Apr 3

PotatoesPlant outdoors · Mar 27 – Apr 10

LettuceSow outdoors · Mar 20 – Apr 3

Carrots, beetsSow outdoors · Mar 27 – Apr 10

TomatoesStart indoors · Feb 20 – Mar 6

TomatoesTransplant · Apr 24 – May 8

Peppers, eggplantStart indoors · Feb 6 – Feb 20

Peppers, eggplantTransplant · May 1 – May 15

BeansSow outdoors · Apr 24 – May 8

Sweet cornSow outdoors · Apr 24 – May 8

Cucumbers, squashSow outdoors · Apr 24 – May 8

Fall lettuce, spinachSow outdoors · Aug 28 – Sep 11

GarlicPlant cloves · Oct 9 – Nov 13

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 17) and first fall frost (Oct 23) 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 21711 came on Mar 15 — 7 days earlier than the 1991–2020 average (Mar 22).

average
Mar 222026
Mar 15

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 7a in Maryland

612 plants native to the lower 48 states, recorded in Maryland, and rated by the USDA to survive 0 °F or colder — the bottom of zone 7a. Each links to its USDA PLANTS profile.

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 Big Pool, MD.

Soil in Big Pool, MD

The soil mapped at the center of ZIP 21711 is Wurno — channery silt loam, well drained.

TextureChannery silt loama good balance for most vegetables

pH6.4slightly acidic; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter1.5%low — add compost

Hydrologic groupCwater soaks in slowly

Farmland classFarmland of statewide importanceUSDA classification

Map unit: Wurno-Nollville channery silt loams, 3 to 8 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 21711; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Big Pool, MD

Summer high87 °Faverage high, July

Winter low23 °Faverage low, January

Hot days29days a year at 90 °F or more

Freezing nights119nights a year at 32 °F or less

Growing degree days3,520base 50 °F — the season’s usable heat

Longest day14 h 59 mindaylight on June 21

Shortest day9 h 21 mindaylight on December 21

Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully

Precipitation43.1 inper year, rain and melted snow

Average high and low, by month

Precipitation by month inches

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Martinsburg 2, WV (14 mi away); precipitation: Falling Waters 2.4 Nw, WV (8 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 7a.

217227a

Clear Spring, MD · 6 mi

254197a

Falling Waters, WV · 9 mi

172367a

Mercersburg, PA · 10 mi

172127a

Big Cove Tannery, PA · 10 mi

254277a

Hedgesville, WV · 11 mi

217507a

Hancock, MD · 12 mi

217957a

Williamsport, MD · 12 mi

254037a

Martinsburg, WV · 13 mi

Maryland planting zones →

Questions about 21711

What planting zone is ZIP code 21711?

ZIP code 21711 (Big Pool, MD) is in USDA hardiness zone 7a on the 2023 map: the coldest night of an average winter reaches 0 to 5 °F (−17.8 to −15 °C).

When is the last frost in Big Pool, MD?

The median last spring frost (32 °F) near 21711 is April 17; after May 1 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Martinsburg 2 station.

When is the first frost in Big Pool, MD?

The median first fall frost near 21711 is October 23, giving a median frost-free growing season of 187 days.

When should I plant tomatoes in 21711?

Start tomato seeds indoors around Feb 20 – Mar 6 and set transplants outside around Apr 24 – May 8, one to three weeks after the median last frost.

How much rain and snow does 21711 get?

About 43.1 inches of precipitation a year (NOAA 1991–2020 normals, Falling Waters 2.4 Nw station).

How hot do summers get in Big Pool, MD?

The average high peaks at 87 °F in July, with about 29 days a year at 90 °F or more.

What kind of soil does 21711 have?

The USDA soil survey maps Wurno at the center of ZIP 21711: channery silt loam, well drained, pH about 6.4 (slightly acidic).

Did spring come early in Big Pool, MD in 2026?

Spring leaf-out near 21711 came on Mar 15 in 2026, 7 days earlier than the 1991–2020 average (Mar 22), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Big Pool, MD?

Intermediate onions: the longest day near 21711 is 14 h 59 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

Did the zone for 21711 change?

Yes. The 2012 USDA map put 21711 in zone 6b; the 2023 map puts it in zone 7a. The newer map uses 1991–2020 data and more weather stations.