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

Planting zone for 20615 — Broomes Island, MD

ZIP code 20615 (Broomes Island, Calvert County) is in USDA zone 8a: the coldest winter night averages 10 to 15 °F. The median last spring frost is March 22 and the first fall frost November 26.

Where ZIP 20615 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 22
First frostNov 26
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 Broomes Island, 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 Broomes Island, MD

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMarch 22median — 50% chance of a later frost
Safe for tender plantsApril 5only 10% chance of frost after
First fall frostNovember 26median — 10% chance by Nov 10
Growing season248 daysfrost-free, median

A hard freeze (28 °F) usually ends around March 10 and returns around December 9.

From the NOAA station Solomons, MD — 8 miles away, elevation 13 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 20615

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Feb 8 – Feb 22
SpinachSow outdoors · Feb 8 – Mar 1
Broccoli, cabbageStart indoors · Jan 11 – Jan 25
Broccoli, cabbageTransplant · Mar 1 – Mar 15
Onion setsPlant outdoors · Feb 22 – Mar 8
PotatoesPlant outdoors · Mar 1 – Mar 15
LettuceSow outdoors · Feb 22 – Mar 8
Carrots, beetsSow outdoors · Mar 1 – Mar 15
TomatoesStart indoors · Jan 25 – Feb 8
TomatoesTransplant · Mar 29 – Apr 12
Peppers, eggplantStart indoors · Jan 11 – Jan 25
Peppers, eggplantTransplant · Apr 5 – Apr 19
BeansSow outdoors · Mar 29 – Apr 12
Sweet cornSow outdoors · Mar 29 – Apr 12
Cucumbers, squashSow outdoors · Mar 29 – Apr 12
Fall lettuce, spinachSow outdoors · Oct 1 – Oct 15
GarlicPlant cloves · Nov 12 – Dec 17
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Mar 22) and first fall frost (Nov 26) 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 20615 came on Mar 11 — 4 days later than the 1991–2020 average (Mar 7).

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.

Trees 84

American basswood100 ft · blooms late spring · low shade tolerance · to −46 °FAmerican beech80 ft · blooms mid spring · low shade tolerance · to −44 °FAmerican chestnut115 ft · blooms early summer · high shade tolerance · to −33 °FAmerican elm120 ft · blooms early spring · medium shade tolerance · to −46 °FAmerican sycamore100 ft · blooms spring · medium shade tolerance · to −34 °Farborvitae50 ft · blooms mid spring · medium shade tolerance · to −33 °F

Shrubs 129

alderleaf buckthorn3 ft · blooms late spring · low shade tolerance · to −33 °FAllegheny serviceberry35 ft · blooms early spring · low shade tolerance · to −38 °Falternateleaf dogwood25 ft · blooms mid spring · low shade tolerance · to −47 °FAmerican beautyberry6 ft · blooms early summer · medium shade tolerance · to −8 °FAmerican black currant3 ft · blooms early spring · to −46 °FAmerican hazelnut10 ft · blooms spring · medium shade tolerance · to −33 °F

Wildflowers & perennials 209

American bur-reed3 ft · blooms indeterminate · medium shade tolerance · to −33 °FAmerican eelgrass1 ft · blooms mid summer · high shade tolerance · to −33 °FAmerican lotus3 ft · blooms mid summer · high shade tolerance · to −36 °FAmerican pokeweed7 ft · blooms mid summer · low shade tolerance · to −33 °FAmerican speedwell0.8 ft · blooms mid summer · low shade tolerance · to −38 °FAmerican spongeplant0.5 ft · blooms mid spring · high shade tolerance · to −24 °F

Grasses 181

American beachgrass2.5 ft · blooms spring · high shade tolerance · to −28 °FAmerican cupscale3 ft · blooms early summer · high shade tolerance · to −18 °Farctic brome3 ft · blooms early summer · low shade tolerance · to −33 °FAtlantic mannagrass3 ft · blooms summer · low shade tolerance · to −8 °Fautumn bluegrass1.5 ft · blooms late spring · medium shade tolerance · to −8 °Fawlfruit sedge4 ft · blooms mid spring · low shade tolerance · to −38 °F

Vines 12

American bittersweet15 ft · blooms spring · low shade tolerance · to −38 °FAmerican wisteria50 ft · blooms spring · low shade tolerance · to −3 °Fdevil's darning needles15 ft · blooms mid summer · medium shade tolerance · to −38 °Ffrost grape83 ft · blooms late spring · medium shade tolerance · to −23 °Fgraybark grape50 ft · blooms late spring · medium shade tolerance · to −8 °Fheartleaf peppervine2 ft · blooms late spring · low shade tolerance · to −8 °F

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 Broomes Island, MD.

Soil in Broomes Island, MD

The soil mapped at the center of ZIP 20615 is Mispillion — mucky peat, very poorly drained.

TextureMucky peattop layer
pH6.5neutral; most vegetables like 6.0–7.0
DrainageVery poorly drainedconsider raised beds
Organic matter77%high
Hydrologic groupA/Ddrains fast once dried out; wet otherwise
Farmland classNot prime farmlandUSDA classification

Map unit: Mispillion and Transquaking soils, 0 to 1 percent slopes, tidally flooded.

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 20615; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Broomes Island, MD

Summer high88 °Faverage high, July
Winter low30 °Faverage low, January
Hot days31days a year at 90 °F or more
Freezing nights59nights a year at 32 °F or less
Growing degree days4,559base 50 °F — the season’s usable heat
Longest day14 h 51 mindaylight on June 21
Shortest day9 h 29 mindaylight on December 21
Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully
Precipitation45.3 inper year, rain and melted snow
Snowfall13 inper year; 7 days with snow on the ground

Average high and low, by month

20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 45 °F, low 30 °F 45°30° JanFebruary: average high 48 °F, low 31 °F 48°31° FebMarch: average high 55 °F, low 38 °F 55°38° MarApril: average high 65 °F, low 47 °F 65°47° AprMay: average high 74 °F, low 58 °F 74°58° MayJune: average high 84 °F, low 68 °F 84°68° JunJuly: average high 88 °F, low 73 °F 88°73° JulAugust: average high 86 °F, low 71 °F 86°71° AugSeptember: average high 80 °F, low 65 °F 80°65° SepOctober: average high 69 °F, low 53 °F 69°53° OctNovember: average high 59 °F, low 43 °F 59°43° NovDecember: average high 50 °F, low 35 °F 50°35° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″4″5″January: 2.91 in precipitation, 3.9 in snowfall 2.9❄4 JanFebruary: 2.84 in precipitation, 6 in snowfall 2.8❄6 FebMarch: 4.00 in precipitation, 1.3 in snowfall 4.0❄1 MarApril: 3.68 in precipitation 3.7 AprMay: 3.66 in precipitation 3.7 MayJune: 4.27 in precipitation 4.3 JunJuly: 4.49 in precipitation 4.5 JulAugust: 4.66 in precipitation 4.7 AugSeptember: 4.15 in precipitation 4.2 SepOctober: 4.03 in precipitation 4.0 OctNovember: 3.07 in precipitation 3.1 NovDecember: 3.54 in precipitation, 1.3 in snowfall 3.5❄1 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Solomons, MD (8 mi away); precipitation: Patuxent River NAS, MD (11 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.

206858a
Saint Leonard, MD · 2 mi
206367b
Hollywood, MD · 4 mi
206767b
Port Republic, MD · 5 mi
206578a
Lusby, MD · 6 mi
206298a
Dowell, MD · 7 mi
206888a
Solomons, MD · 7 mi
206357b
Helen, MD · 8 mi
206787b
Prince Frederick, MD · 8 mi

Maryland planting zones →

Questions about 20615

What planting zone is ZIP code 20615?

ZIP code 20615 (Broomes Island, 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 Broomes Island, MD?

The median last spring frost (32 °F) near 20615 is March 22; after April 5 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Solomons station.

When is the first frost in Broomes Island, MD?

The median first fall frost near 20615 is November 26, giving a median frost-free growing season of 248 days.

When should I plant tomatoes in 20615?

Start tomato seeds indoors around Jan 25 – Feb 8 and set transplants outside around Mar 29 – Apr 12, one to three weeks after the median last frost.

How much rain and snow does 20615 get?

About 45.3 inches of precipitation a year and 13 inches of snowfall (NOAA 1991–2020 normals, Patuxent River NAS station).

How hot do summers get in Broomes Island, MD?

The average high peaks at 88 °F in July, with about 31 days a year at 90 °F or more.

What kind of soil does 20615 have?

The USDA soil survey maps Mispillion at the center of ZIP 20615: mucky peat, very poorly drained, pH about 6.5 (neutral).

Did spring come early in Broomes Island, MD in 2026?

Spring leaf-out near 20615 came on Mar 11 in 2026, 4 days later than the 1991–2020 average (Mar 7), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Broomes Island, MD?

Intermediate onions: the longest day near 20615 is 14 h 51 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

Did the zone for 20615 change?

Yes. The 2012 USDA map put 20615 in zone 7b; the 2023 map puts it in zone 8a. The newer map uses 1991–2020 data and more weather stations.