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

Planting zone for 20689 — Sunderland, MD

ZIP code 20689 (Sunderland, Calvert County) is in USDA zone 7b: the coldest winter night averages 5 to 10 °F. The median last spring frost is April 17 and the first fall frost October 27.

Where ZIP 20689 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 17
First frostOct 27
2012 zone7b

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 7b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Sunderland, 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 Sunderland, 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 2only 10% chance of frost after
First fall frostOctober 27median — 10% chance by Oct 12
Growing season195 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 2 and returns around November 6.

From the NOAA station Mechanicsville 5 Ne, MD — 14 miles away, elevation 102 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 20689

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 · Sep 1 – Sep 15
GarlicPlant cloves · Oct 13 – Nov 17
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 17) and first fall frost (Oct 27) 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 20689 came on Mar 11 — about the same time as the 1991–2020 average (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).

Soil in Sunderland, MD

The soil mapped at the center of ZIP 20689 is Dodon — fine sandy loam, moderately well drained.

TextureFine sandy loamdrains and warms fast; dries out and needs more feeding
pH4.9strongly acidic; most vegetables like 6.0–7.0
DrainageModerately well drainednatural drainage class
Organic matter4.42%moderate
Hydrologic groupB/Dmoderate when drained; wet otherwise
Farmland classNot prime farmlandUSDA classification

Map unit: Dodon and Marr soils, 25 to 80 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 20689; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Sunderland, MD

Summer high85 °Faverage high, July
Winter low25 °Faverage low, January
Hot days16days a year at 90 °F or more
Freezing nights98nights a year at 32 °F or less
Growing degree days3,649base 50 °F — the season’s usable heat
Longest day14 h 52 mindaylight on June 21
Shortest day9 h 27 mindaylight on December 21
Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully
Precipitation47.8 inper year, rain and melted snow

Average high and low, by month

10°20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 44 °F, low 25 °F 44°25° JanFebruary: average high 48 °F, low 26 °F 48°26° FebMarch: average high 56 °F, low 33 °F 56°33° MarApril: average high 67 °F, low 43 °F 67°43° AprMay: average high 74 °F, low 52 °F 74°52° MayJune: average high 82 °F, low 61 °F 82°61° JunJuly: average high 85 °F, low 66 °F 85°66° JulAugust: average high 83 °F, low 64 °F 83°64° AugSeptember: average high 77 °F, low 58 °F 77°58° SepOctober: average high 66 °F, low 46 °F 66°46° OctNovember: average high 57 °F, low 36 °F 57°36° NovDecember: average high 48 °F, low 29 °F 48°29° Dec

Precipitation by month inches

0″1″2″3″4″5″6″January: 3.25 in precipitation 3.3 JanFebruary: 2.96 in precipitation 3.0 FebMarch: 3.79 in precipitation 3.8 MarApril: 3.27 in precipitation 3.3 AprMay: 4.22 in precipitation 4.2 MayJune: 4.51 in precipitation 4.5 JunJuly: 4.60 in precipitation 4.6 JulAugust: 5.10 in precipitation 5.1 AugSeptember: 5.22 in precipitation 5.2 SepOctober: 4.19 in precipitation 4.2 OctNovember: 2.93 in precipitation 2.9 NovDecember: 3.72 in precipitation 3.7 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Mechanicsville 5 Ne, MD (14 mi away); precipitation: Huntingtown 2.9 Nnw, MD (3 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

207367b
Owings, MD · 2 mi
207328a
Chesapeake Beach, MD · 3 mi
207148a
North Beach, MD · 4 mi
207587b
Friendship, MD · 4 mi
206397b
Huntingtown, MD · 5 mi
207547b
Dunkirk, MD · 6 mi
207798a
Tracys Landing, MD · 6 mi
207518a
Deale, MD · 9 mi

Maryland planting zones →

Questions about 20689

What planting zone is ZIP code 20689?

ZIP code 20689 (Sunderland, 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 Sunderland, MD?

The median last spring frost (32 °F) near 20689 is April 17; after May 2 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Mechanicsville 5 Ne station.

When is the first frost in Sunderland, MD?

The median first fall frost near 20689 is October 27, giving a median frost-free growing season of 195 days.

When should I plant tomatoes in 20689?

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 20689 get?

About 47.8 inches of precipitation a year (NOAA 1991–2020 normals, Huntingtown 2.9 Nnw station).

How hot do summers get in Sunderland, MD?

The average high peaks at 85 °F in July, with about 16 days a year at 90 °F or more.

What kind of soil does 20689 have?

The USDA soil survey maps Dodon at the center of ZIP 20689: fine sandy loam, moderately well drained, pH about 4.9 (strongly acidic).

Did spring come early in Sunderland, MD in 2026?

Spring leaf-out near 20689 came on Mar 11 in 2026, about the same as the 1991–2020 average (Mar 10), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Sunderland, MD?

Intermediate onions: the longest day near 20689 is 14 h 52 min, so day-neutral types bulb best; long-day varieties may not bulb fully.