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

Planting zone for 20738 — Riverdale, MD

ZIP code 20738 (Riverdale, Prince George's County) is in USDA zone 7b: the coldest winter night averages 5 to 10 °F. The median last spring frost is April 9 and the first fall frost October 29.

Where ZIP 20738 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 frostApr 9
First frostOct 29
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 Riverdale, 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 Riverdale, MD

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 9median — 50% chance of a later frost
Safe for tender plantsApril 24only 10% chance of frost after
First fall frostOctober 29median — 10% chance by Oct 14
Growing season203 daysfrost-free, median

A hard freeze (28 °F) usually ends around March 30 and returns around November 10.

From the NOAA station Upper Marlboro 3 Nnw, MD — 6 miles away, elevation 131 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 20738

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Feb 26 – Mar 12
SpinachSow outdoors · Feb 26 – Mar 19
Broccoli, cabbageStart indoors · Jan 29 – Feb 12
Broccoli, cabbageTransplant · Mar 19 – Apr 2
Onion setsPlant outdoors · Mar 12 – Mar 26
PotatoesPlant outdoors · Mar 19 – Apr 2
LettuceSow outdoors · Mar 12 – Mar 26
Carrots, beetsSow outdoors · Mar 19 – Apr 2
TomatoesStart indoors · Feb 12 – Feb 26
TomatoesTransplant · Apr 16 – Apr 30
Peppers, eggplantStart indoors · Jan 29 – Feb 12
Peppers, eggplantTransplant · Apr 23 – May 7
BeansSow outdoors · Apr 16 – Apr 30
Sweet cornSow outdoors · Apr 16 – Apr 30
Cucumbers, squashSow outdoors · Apr 16 – Apr 30
Fall lettuce, spinachSow outdoors · Sep 3 – Sep 17
GarlicPlant cloves · Oct 15 – Nov 19
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 9) and first fall frost (Oct 29) 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 20738 came on Mar 10 — about the same time as the 1991–2020 average (Mar 12).

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 Riverdale, MD.

Soil in Riverdale, MD

The soil mapped at the center of ZIP 20738 is Sassafras — sandy loam, well drained.

TextureSandy loamdrains and warms fast; dries out and needs more feeding
pH4.9strongly acidic; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter2%moderate
Hydrologic groupBwater soaks in moderately
Farmland classNot prime farmlandUSDA classification

Map unit: Sassafras-Urban land complex, 0 to 5 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 20738; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Riverdale, MD

Summer high88 °Faverage high, July
Winter low25 °Faverage low, January
Hot days32days a year at 90 °F or more
Freezing nights103nights a year at 32 °F or less
Growing degree days3,960base 50 °F — the season’s usable heat
Longest day14 h 53 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
Precipitation46.5 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 47 °F, low 26 °F 47°26° FebMarch: average high 55 °F, low 33 °F 55°33° MarApril: average high 67 °F, low 44 °F 67°44° AprMay: average high 75 °F, low 54 °F 75°54° MayJune: average high 84 °F, low 63 °F 84°63° JunJuly: average high 88 °F, low 67 °F 88°67° JulAugust: average high 86 °F, low 65 °F 86°65° AugSeptember: average high 80 °F, low 58 °F 80°58° SepOctober: average high 69 °F, low 46 °F 69°46° OctNovember: average high 58 °F, low 36 °F 58°36° NovDecember: average high 48 °F, low 29 °F 48°29° Dec

Precipitation by month inches

0″1″2″3″4″5″6″January: 3.10 in precipitation 3.1 JanFebruary: 2.82 in precipitation 2.8 FebMarch: 3.96 in precipitation 4.0 MarApril: 3.46 in precipitation 3.5 AprMay: 4.42 in precipitation 4.4 MayJune: 4.22 in precipitation 4.2 JunJuly: 5.06 in precipitation 5.1 JulAugust: 4.05 in precipitation 4.0 AugSeptember: 4.33 in precipitation 4.3 SepOctober: 4.03 in precipitation 4.0 OctNovember: 3.23 in precipitation 3.2 NovDecember: 3.78 in precipitation 3.8 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Upper Marlboro 3 Nnw, MD (6 mi away); precipitation: Suitland 2.1 Se, MD (2 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.

206977b
Southern Md Facility, MD · <1 mi
207037b
Lanham, MD · <1 mi
207177b
Bowie, MD · <1 mi
207187a
Bowie, MD · <1 mi
207197b
Bowie, MD · <1 mi
207417b
College Park, MD · <1 mi
207498a
Fort Washington, MD · <1 mi
207537b
District Heights, MD · <1 mi

All 2 ZIP codes in Riverdale → · Maryland planting zones →

Questions about 20738

What planting zone is ZIP code 20738?

ZIP code 20738 (Riverdale, 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 Riverdale, MD?

The median last spring frost (32 °F) near 20738 is April 9; after April 24 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Upper Marlboro 3 Nnw station.

When is the first frost in Riverdale, MD?

The median first fall frost near 20738 is October 29, giving a median frost-free growing season of 203 days.

When should I plant tomatoes in 20738?

Start tomato seeds indoors around Feb 12 – Feb 26 and set transplants outside around Apr 16 – Apr 30, one to three weeks after the median last frost.

How much rain and snow does 20738 get?

About 46.5 inches of precipitation a year (NOAA 1991–2020 normals, Suitland 2.1 Se station).

How hot do summers get in Riverdale, MD?

The average high peaks at 88 °F in July, with about 32 days a year at 90 °F or more.

What kind of soil does 20738 have?

The USDA soil survey maps Sassafras at the center of ZIP 20738: sandy loam, well drained, pH about 4.9 (strongly acidic).

Did spring come early in Riverdale, MD in 2026?

Spring leaf-out near 20738 came on Mar 10 in 2026, about the same as the 1991–2020 average (Mar 12), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Riverdale, MD?

Intermediate onions: the longest day near 20738 is 14 h 53 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

Did the zone for 20738 change?

Yes. The 2012 USDA map put 20738 in zone 7a; the 2023 map puts it in zone 7b. The newer map uses 1991–2020 data and more weather stations.