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

Planting zone for 20603 — Waldorf, MD

ZIP code 20603 (Waldorf, Charles County) is in USDA zone 7b: the coldest winter night averages 5 to 10 °F. The median last spring frost is April 3 and the first fall frost November 8.

Where ZIP 20603 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 3

First frostNov 8

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 Waldorf, 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 Waldorf, MD

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostApril 3median — 50% chance of a later frost

Safe for tender plantsApril 15only 10% chance of frost after

First fall frostNovember 8median — 10% chance by Oct 24

Growing season217 daysfrost-free, median

A hard freeze (28 °F) usually ends around March 21 and returns around November 19.

From the NOAA station Oxon Hill, MD — 12 miles away, elevation 190 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 20603

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Feb 20 – Mar 6

SpinachSow outdoors · Feb 20 – Mar 13

Broccoli, cabbageStart indoors · Jan 23 – Feb 6

Broccoli, cabbageTransplant · Mar 13 – Mar 27

Onion setsPlant outdoors · Mar 6 – Mar 20

PotatoesPlant outdoors · Mar 13 – Mar 27

LettuceSow outdoors · Mar 6 – Mar 20

Carrots, beetsSow outdoors · Mar 13 – Mar 27

TomatoesStart indoors · Feb 6 – Feb 20

TomatoesTransplant · Apr 10 – Apr 24

Peppers, eggplantStart indoors · Jan 23 – Feb 6

Peppers, eggplantTransplant · Apr 17 – May 1

BeansSow outdoors · Apr 10 – Apr 24

Sweet cornSow outdoors · Apr 10 – Apr 24

Cucumbers, squashSow outdoors · Apr 10 – Apr 24

Fall lettuce, spinachSow outdoors · Sep 13 – Sep 27

GarlicPlant cloves · Oct 25 – Nov 29

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 3) and first fall frost (Nov 8) 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 20603 came on Mar 10 — about the same time as the 1991–2020 average (Mar 9).

average
Mar 92026
Mar 10

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 Waldorf, MD.

Soil in Waldorf, MD

The soil mapped at the center of ZIP 20603 is Woodstown — sandy loam, moderately well drained.

TextureSandy loamdrains and warms fast; dries out and needs more feeding

pH5.7moderately acidic; most vegetables like 6.0–7.0

DrainageModerately well drainednatural drainage class

Organic matter1.95%low — add compost

Hydrologic groupCwater soaks in slowly

Farmland classprime farmlandUSDA classification

Map unit: Woodstown sandy loam, 2 to 5 percent slopes, Northern Coastal Plain.

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 20603; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Waldorf, MD

Summer high88 °Faverage high, July

Winter low27 °Faverage low, January

Hot days38days a year at 90 °F or more

Freezing nights80nights a year at 32 °F or less

Growing degree days4,190base 50 °F — the season’s usable heat

Longest day14 h 52 mindaylight on June 21

Shortest day9 h 28 mindaylight on December 21

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

Precipitation47.1 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: Oxon Hill, MD (12 mi away); precipitation: Waldorf 3.3 S, MD (4 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 7b.

206957b

White Plains, MD · 3 mi

Bryans Road, MD · 7 mi

206467b

La Plata, MD · 8 mi

207447b

Fort Washington, MD · 8 mi

All 4 ZIP codes in Waldorf → · Maryland planting zones →

Questions about 20603

What planting zone is ZIP code 20603?

ZIP code 20603 (Waldorf, 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 Waldorf, MD?

The median last spring frost (32 °F) near 20603 is April 3; after April 15 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Oxon Hill station.

When is the first frost in Waldorf, MD?

The median first fall frost near 20603 is November 8, giving a median frost-free growing season of 217 days.

When should I plant tomatoes in 20603?

Start tomato seeds indoors around Feb 6 – Feb 20 and set transplants outside around Apr 10 – Apr 24, one to three weeks after the median last frost.

How much rain and snow does 20603 get?

About 47.1 inches of precipitation a year (NOAA 1991–2020 normals, Waldorf 3.3 S station).

How hot do summers get in Waldorf, MD?

The average high peaks at 88 °F in July, with about 38 days a year at 90 °F or more.

What kind of soil does 20603 have?

The USDA soil survey maps Woodstown at the center of ZIP 20603: sandy loam, moderately well drained, pH about 5.7 (moderately acidic).

Did spring come early in Waldorf, MD in 2026?

Spring leaf-out near 20603 came on Mar 10 in 2026, about the same as the 1991–2020 average (Mar 9), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Waldorf, MD?

Intermediate onions: the longest day near 20603 is 14 h 52 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

Did the zone for 20603 change?

Yes. The 2012 USDA map put 20603 in zone 7a; the 2023 map puts it in zone 7b. The newer map uses 1991–2020 data and more weather stations.