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

Planting zone for 21912 — Warwick, MD

ZIP code 21912 (Warwick, Cecil County) is in USDA zone 7b: the coldest winter night averages 5 to 10 °F. The median last spring frost is April 7 and the first fall frost November 2.

Where ZIP 21912 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.

Zone7b5 to 10 °F

Coldest night−15 to −12.2 °C

Last frostApr 7

First frostNov 2

2012 zone7a

Was 7a 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 7b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Warwick, 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 Warwick, MD

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostApril 7median — 50% chance of a later frost

Safe for tender plantsApril 21only 10% chance of frost after

First fall frostNovember 2median — 10% chance by Oct 19

Growing season208 daysfrost-free, median

A hard freeze (28 °F) usually ends around March 27 and returns around November 13.

From the NOAA station Newark Ag Farm, DE — 17 miles away, elevation 105 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 21912

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Feb 24 – Mar 10

SpinachSow outdoors · Feb 24 – Mar 17

Broccoli, cabbageStart indoors · Jan 27 – Feb 10

Broccoli, cabbageTransplant · Mar 17 – Mar 31

Onion setsPlant outdoors · Mar 10 – Mar 24

PotatoesPlant outdoors · Mar 17 – Mar 31

LettuceSow outdoors · Mar 10 – Mar 24

Carrots, beetsSow outdoors · Mar 17 – Mar 31

TomatoesStart indoors · Feb 10 – Feb 24

TomatoesTransplant · Apr 14 – Apr 28

Peppers, eggplantStart indoors · Jan 27 – Feb 10

Peppers, eggplantTransplant · Apr 21 – May 5

BeansSow outdoors · Apr 14 – Apr 28

Sweet cornSow outdoors · Apr 14 – Apr 28

Cucumbers, squashSow outdoors · Apr 14 – Apr 28

Fall lettuce, spinachSow outdoors · Sep 7 – Sep 21

GarlicPlant cloves · Oct 19 – Nov 23

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 7) and first fall frost (Nov 2) 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 21912 came on Mar 15 — 4 days earlier than the 1991–2020 average (Mar 19).

average
Mar 192026
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 7b in Maryland

618 plants native to the lower 48 states, recorded in Maryland, and rated by the USDA to survive 5 °F or colder — the bottom of zone 7b. 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 Warwick, MD.

Soil in Warwick, MD

The soil mapped at the center of ZIP 21912 is Nassawango — silt loam, well drained.

TextureSilt loama good balance for most vegetables

pH6.3slightly acidic; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter1.22%low — add compost

Hydrologic groupCwater soaks in slowly

Farmland classprime farmlandUSDA classification

Map unit: Nassawango silt loam, 2 to 5 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 21912; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Warwick, MD

Summer high89 °Faverage high, July

Winter low25 °Faverage low, January

Hot days33days a year at 90 °F or more

Freezing nights97nights a year at 32 °F or less

Growing degree days3,866base 50 °F — the season’s usable heat

Longest day14 h 57 mindaylight on June 21

Shortest day9 h 23 mindaylight on December 21

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

Precipitation48.6 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: Newark Ag Farm, DE (17 mi away); precipitation: Charlestown 0.4 Wsw, MD (14 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 7b.

219137b

Cecilton, MD · 3 mi

219307b

Georgetown, MD · 5 mi

219157b

Chesapeake City, MD · 6 mi

216357b

Galena, MD · 6 mi

219197b

Earleville, MD · 6 mi

Middletown, DE · 9 mi

Maryland planting zones →

Questions about 21912

What planting zone is ZIP code 21912?

ZIP code 21912 (Warwick, MD) is in USDA hardiness zone 7b on the 2023 map: the coldest night of an average winter reaches 5 to 10 °F (−15 to −12.2 °C).

When is the last frost in Warwick, MD?

The median last spring frost (32 °F) near 21912 is April 7; after April 21 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Newark Ag Farm station.

When is the first frost in Warwick, MD?

The median first fall frost near 21912 is November 2, giving a median frost-free growing season of 208 days.

When should I plant tomatoes in 21912?

Start tomato seeds indoors around Feb 10 – Feb 24 and set transplants outside around Apr 14 – Apr 28, one to three weeks after the median last frost.

How much rain and snow does 21912 get?

About 48.6 inches of precipitation a year (NOAA 1991–2020 normals, Charlestown 0.4 Wsw station).

How hot do summers get in Warwick, MD?

The average high peaks at 89 °F in July, with about 33 days a year at 90 °F or more.

What kind of soil does 21912 have?

The USDA soil survey maps Nassawango at the center of ZIP 21912: silt loam, well drained, pH about 6.3 (slightly acidic).

Did spring come early in Warwick, MD in 2026?

Spring leaf-out near 21912 came on Mar 15 in 2026, 4 days earlier than the 1991–2020 average (Mar 19), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Warwick, MD?

Intermediate onions: the longest day near 21912 is 14 h 57 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

Did the zone for 21912 change?

Yes. The 2012 USDA map put 21912 in zone 7a; the 2023 map puts it in zone 7b. The newer map uses 1991–2020 data and more weather stations.