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

Planting zone for 20731 — Capitol Heights, MD

ZIP code 20731 (Capitol Heights, Prince George's County) is in USDA zone 7b: the coldest winter night averages 5 to 10 °F. The median last spring frost is March 29 and the first fall frost November 8.

Where ZIP 20731 is

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 frostMar 29
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 Capitol Heights, 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 Capitol Heights, MD

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMarch 29median — 50% chance of a later frost
Safe for tender plantsApril 11only 10% chance of frost after
First fall frostNovember 8median — 10% chance by Oct 26
Growing season224 daysfrost-free, median

A hard freeze (28 °F) usually ends around March 17 and returns around November 20.

From the NOAA station Natl Arboretum Dc, MD — 4 miles away, elevation 49 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 20731

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Feb 15 – Mar 1
SpinachSow outdoors · Feb 15 – Mar 8
Broccoli, cabbageStart indoors · Jan 18 – Feb 1
Broccoli, cabbageTransplant · Mar 8 – Mar 22
Onion setsPlant outdoors · Mar 1 – Mar 15
PotatoesPlant outdoors · Mar 8 – Mar 22
LettuceSow outdoors · Mar 1 – Mar 15
Carrots, beetsSow outdoors · Mar 8 – Mar 22
TomatoesStart indoors · Feb 1 – Feb 15
TomatoesTransplant · Apr 5 – Apr 19
Peppers, eggplantStart indoors · Jan 18 – Feb 1
Peppers, eggplantTransplant · Apr 12 – Apr 26
BeansSow outdoors · Apr 5 – Apr 19
Sweet cornSow outdoors · Apr 5 – Apr 19
Cucumbers, squashSow outdoors · Apr 5 – Apr 19
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 (Mar 29) 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 20731 came on Mar 10 — 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).

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.

Trees 83

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 127

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 206

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 176

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 Capitol Heights, MD.

Soil in Capitol Heights, MD

The soil mapped at the center of ZIP 20731 is Christiana — silt loam, moderately well drained.

TextureSilt loama good balance for most vegetables
pH4.3strongly acidic; most vegetables like 6.0–7.0
DrainageModerately well drainednatural drainage class
Organic matter2%moderate
Hydrologic groupDwater soaks in very slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Christiana-Downer-Urban land complex, 5 to 15 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 20731; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Capitol Heights, MD

Summer high90 °Faverage high, July
Winter low28 °Faverage low, January
Hot days48days a year at 90 °F or more
Freezing nights84nights a year at 32 °F or less
Growing degree days4,518base 50 °F — the season’s usable heat
Longest day14 h 54 mindaylight on June 21
Shortest day9 h 26 mindaylight on December 21
Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully
Precipitation45.6 inper year, rain and melted snow
Snowfall10 inper year; 12 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 28 °F 45°28° JanFebruary: average high 48 °F, low 30 °F 48°30° FebMarch: average high 56 °F, low 37 °F 56°37° MarApril: average high 68 °F, low 46 °F 68°46° AprMay: average high 77 °F, low 57 °F 77°57° MayJune: average high 85 °F, low 66 °F 85°66° JunJuly: average high 90 °F, low 71 °F 90°71° JulAugust: average high 88 °F, low 69 °F 88°69° AugSeptember: average high 82 °F, low 62 °F 82°62° SepOctober: average high 70 °F, low 49 °F 70°49° OctNovember: average high 58 °F, low 39 °F 58°39° NovDecember: average high 49 °F, low 32 °F 49°32° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″4″5″January: 3.03 in precipitation, 4.7 in snowfall 3.0❄5 JanFebruary: 2.77 in precipitation, 2.3 in snowfall 2.8❄2 FebMarch: 3.96 in precipitation, 1.4 in snowfall 4.0❄1 MarApril: 3.44 in precipitation 3.4 AprMay: 4.32 in precipitation 4.3 MayJune: 4.56 in precipitation 4.6 JunJuly: 4.62 in precipitation 4.6 JulAugust: 3.67 in precipitation 3.7 AugSeptember: 4.12 in precipitation 4.1 SepOctober: 4.23 in precipitation 4.2 OctNovember: 3.20 in precipitation 3.2 NovDecember: 3.67 in precipitation, 1.3 in snowfall 3.7❄1 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Natl Arboretum Dc, MD (4 mi away); precipitation: Natl Arboretum Dc, MD (4 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.

207437b
Capitol Heights, MD · 1 mi
200198a
Washington, DC · 1 mi
207527b
Suitland, MD · 3 mi
207477b
District Heights, MD · 3 mi
207857b
Hyattsville, MD · 3 mi
207467b
Suitland, MD · 3 mi
200207b
Washington, DC · 4 mi
200028a
Washington, DC · 4 mi

All 5 ZIP codes in Capitol Heights → · Maryland planting zones →

Questions about 20731

What planting zone is ZIP code 20731?

ZIP code 20731 (Capitol Heights, 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 Capitol Heights, MD?

The median last spring frost (32 °F) near 20731 is March 29; after April 11 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Natl Arboretum Dc station.

When is the first frost in Capitol Heights, MD?

The median first fall frost near 20731 is November 8, giving a median frost-free growing season of 224 days.

When should I plant tomatoes in 20731?

Start tomato seeds indoors around Feb 1 – Feb 15 and set transplants outside around Apr 5 – Apr 19, one to three weeks after the median last frost.

How much rain and snow does 20731 get?

About 45.6 inches of precipitation a year and 10 inches of snowfall (NOAA 1991–2020 normals, Natl Arboretum Dc station).

How hot do summers get in Capitol Heights, MD?

The average high peaks at 90 °F in July, with about 48 days a year at 90 °F or more.

What kind of soil does 20731 have?

The USDA soil survey maps Christiana at the center of ZIP 20731: silt loam, moderately well drained, pH about 4.3 (strongly acidic).

Did spring come early in Capitol Heights, MD in 2026?

Spring leaf-out near 20731 came on Mar 10 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 Capitol Heights, MD?

Intermediate onions: the longest day near 20731 is 14 h 54 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

Did the zone for 20731 change?

Yes. The 2012 USDA map put 20731 in zone 7a; the 2023 map puts it in zone 7b. The newer map uses 1991–2020 data and more weather stations.