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

Planting zone for 21405 — Annapolis, MD

ZIP code 21405 (Annapolis, Anne Arundel County) is in USDA zone 8a: the coldest winter night averages 10 to 15 °F. The median last spring frost is March 27 and the first fall frost November 13.

Where ZIP 21405 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.

Zone8a10 to 15 °F

Coldest night−12.2 to −9.4 °C

Last frostMar 27

First frostNov 13

2012 zone7b

Was 7b 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 8a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Annapolis, 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 Annapolis, MD

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostMarch 27median — 50% chance of a later frost

Safe for tender plantsApril 9only 10% chance of frost after

First fall frostNovember 13median — 10% chance by Nov 1

Growing season234 daysfrost-free, median

A hard freeze (28 °F) usually ends around March 14 and returns around November 28.

From the NOAA station Annapolis Police Brks, MD — 3 miles away, elevation 26 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 21405

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Feb 13 – Feb 27

SpinachSow outdoors · Feb 13 – Mar 6

Broccoli, cabbageStart indoors · Jan 16 – Jan 30

Broccoli, cabbageTransplant · Mar 6 – Mar 20

Onion setsPlant outdoors · Feb 27 – Mar 13

PotatoesPlant outdoors · Mar 6 – Mar 20

LettuceSow outdoors · Feb 27 – Mar 13

Carrots, beetsSow outdoors · Mar 6 – Mar 20

TomatoesStart indoors · Jan 30 – Feb 13

TomatoesTransplant · Apr 3 – Apr 17

Peppers, eggplantStart indoors · Jan 16 – Jan 30

Peppers, eggplantTransplant · Apr 10 – Apr 24

BeansSow outdoors · Apr 3 – Apr 17

Sweet cornSow outdoors · Apr 3 – Apr 17

Cucumbers, squashSow outdoors · Apr 3 – Apr 17

Fall lettuce, spinachSow outdoors · Sep 18 – Oct 2

GarlicPlant cloves · Oct 30 – Dec 4

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Mar 27) and first fall frost (Nov 13) 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 21405 came on Mar 13 — about the same time as the 1991–2020 average (Mar 13).

average
Mar 132026
Mar 13

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 8a in Maryland

629 plants native to the lower 48 states, recorded in Maryland, and rated by the USDA to survive 10 °F or colder — the bottom of zone 8a. 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 Annapolis, MD.

Soil in Annapolis, MD

The soil mapped at the center of ZIP 21405 is Annapolis — fine sandy loam, well drained.

TextureFine sandy loamdrains and warms fast; dries out and needs more feeding

pH5.4strongly acidic; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter0.93%low — add compost

Hydrologic groupCwater soaks in slowly

Farmland classNot prime farmlandUSDA classification

Map unit: Annapolis fine sandy loam, 15 to 25 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 21405; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Annapolis, MD

Summer high89 °Faverage high, July

Winter low29 °Faverage low, January

Hot days40days a year at 90 °F or more

Freezing nights81nights a year at 32 °F or less

Growing degree days4,561base 50 °F — the season’s usable heat

Longest day14 h 55 mindaylight on June 21

Shortest day9 h 25 mindaylight on December 21

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

Precipitation44.7 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: Annapolis Police Brks, MD (3 mi away); precipitation: Pasadena 2.6 Ese, MD (5 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

214017b

Annapolis, MD · 3 mi

210327b

Crownsville, MD · 3 mi

210128a

Arnold, MD · 3 mi

211468a

Severna Park, MD · 4 mi

210628a

Glen Burnie, MD · 4 mi

All 8 ZIP codes in Annapolis → · Maryland planting zones →

Questions about 21405

What planting zone is ZIP code 21405?

ZIP code 21405 (Annapolis, MD) is in USDA hardiness zone 8a on the 2023 map: the coldest night of an average winter reaches 10 to 15 °F (−12.2 to −9.4 °C).

When is the last frost in Annapolis, MD?

The median last spring frost (32 °F) near 21405 is March 27; after April 9 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Annapolis Police Brks station.

When is the first frost in Annapolis, MD?

The median first fall frost near 21405 is November 13, giving a median frost-free growing season of 234 days.

When should I plant tomatoes in 21405?

Start tomato seeds indoors around Jan 30 – Feb 13 and set transplants outside around Apr 3 – Apr 17, one to three weeks after the median last frost.

How much rain and snow does 21405 get?

About 44.7 inches of precipitation a year (NOAA 1991–2020 normals, Pasadena 2.6 Ese station).

How hot do summers get in Annapolis, MD?

The average high peaks at 89 °F in July, with about 40 days a year at 90 °F or more.

What kind of soil does 21405 have?

The USDA soil survey maps Annapolis at the center of ZIP 21405: fine sandy loam, well drained, pH about 5.4 (strongly acidic).

Did spring come early in Annapolis, MD in 2026?

Spring leaf-out near 21405 came on Mar 13 in 2026, about the same as the 1991–2020 average (Mar 13), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Annapolis, MD?

Intermediate onions: the longest day near 21405 is 14 h 55 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

Did the zone for 21405 change?

Yes. The 2012 USDA map put 21405 in zone 7b; the 2023 map puts it in zone 8a. The newer map uses 1991–2020 data and more weather stations.