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

Planting zone for 20847 — Rockville, MD

ZIP code 20847 (Rockville, Montgomery County) is in USDA zone 7b: the coldest winter night averages 5 to 10 °F. The median last spring frost is April 1 and the first fall frost November 6.

Where ZIP 20847 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 1
First frostNov 6
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 Rockville, 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 Rockville, MD

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 1median — 50% chance of a later frost
Safe for tender plantsApril 15only 10% chance of frost after
First fall frostNovember 6median — 10% chance by Oct 24
Growing season219 daysfrost-free, median

A hard freeze (28 °F) usually ends around March 22 and returns around November 19.

From the NOAA station Rockville 1 Ne, MD — within 1 mile, elevation 440 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 20847

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Feb 18 – Mar 4
SpinachSow outdoors · Feb 18 – Mar 11
Broccoli, cabbageStart indoors · Jan 21 – Feb 4
Broccoli, cabbageTransplant · Mar 11 – Mar 25
Onion setsPlant outdoors · Mar 4 – Mar 18
PotatoesPlant outdoors · Mar 11 – Mar 25
LettuceSow outdoors · Mar 4 – Mar 18
Carrots, beetsSow outdoors · Mar 11 – Mar 25
TomatoesStart indoors · Feb 4 – Feb 18
TomatoesTransplant · Apr 8 – Apr 22
Peppers, eggplantStart indoors · Jan 21 – Feb 4
Peppers, eggplantTransplant · Apr 15 – Apr 29
BeansSow outdoors · Apr 8 – Apr 22
Sweet cornSow outdoors · Apr 8 – Apr 22
Cucumbers, squashSow outdoors · Apr 8 – Apr 22
Fall lettuce, spinachSow outdoors · Sep 11 – Sep 25
GarlicPlant cloves · Oct 23 – Nov 27
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 1) and first fall frost (Nov 6) 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 20847 came on Mar 12 — 4 days earlier than the 1991–2020 average (Mar 16).

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 Rockville, MD.

Soil in Rockville, MD

The soil mapped at the center of ZIP 20847 is Udorthents — loam, well drained. Much of the area is built over (urban land); this is the natural soil underneath.

TextureLoama good balance for most vegetables
pH5.8moderately acidic; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter1.5%low — add compost
Hydrologic groupCwater soaks in slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Urban land.

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 20847; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Rockville, MD

Summer high87 °Faverage high, July
Winter low27 °Faverage low, January
Hot days23days a year at 90 °F or more
Freezing nights86nights a year at 32 °F or less
Growing degree days3,981base 50 °F — the season’s usable heat
Longest day14 h 55 mindaylight on June 21
Shortest day9 h 25 mindaylight on December 21
Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully
Precipitation41.3 inper year, rain and melted snow

Average high and low, by month

20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 42 °F, low 27 °F 42°27° JanFebruary: average high 45 °F, low 28 °F 45°28° FebMarch: average high 54 °F, low 36 °F 54°36° MarApril: average high 66 °F, low 46 °F 66°46° AprMay: average high 74 °F, low 55 °F 74°55° MayJune: average high 82 °F, low 64 °F 82°64° JunJuly: average high 87 °F, low 69 °F 87°69° JulAugust: average high 85 °F, low 67 °F 85°67° AugSeptember: average high 78 °F, low 60 °F 78°60° SepOctober: average high 66 °F, low 48 °F 66°48° OctNovember: average high 56 °F, low 38 °F 56°38° NovDecember: average high 46 °F, low 31 °F 46°31° Dec

Precipitation by month inches

0″1″2″3″4″5″January: 3.11 in precipitation 3.1 JanFebruary: 2.60 in precipitation 2.6 FebMarch: 3.66 in precipitation 3.7 MarApril: 3.23 in precipitation 3.2 AprMay: 3.55 in precipitation 3.5 MayJune: 3.96 in precipitation 4.0 JunJuly: 3.98 in precipitation 4.0 JulAugust: 3.05 in precipitation 3.0 AugSeptember: 4.01 in precipitation 4.0 SepOctober: 3.52 in precipitation 3.5 OctNovember: 3.27 in precipitation 3.3 NovDecember: 3.38 in precipitation 3.4 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Rockville 1 Ne, MD (within 1 mile); precipitation: Rockville 1 Ne, MD (within 1 mile). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 7b.

208497b
Rockville, MD · <1 mi
208577b
Rockville, MD · <1 mi
208837b
Gaithersburg, MD · <1 mi
208507b
Rockville, MD · 2 mi
208517b
Rockville, MD · 2 mi
208527b
Rockville, MD · 3 mi
208537b
Rockville, MD · 3 mi
208557b
Derwood, MD · 4 mi

All 8 ZIP codes in Rockville → · Maryland planting zones →

Questions about 20847

What planting zone is ZIP code 20847?

ZIP code 20847 (Rockville, 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 Rockville, MD?

The median last spring frost (32 °F) near 20847 is April 1; after April 15 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Rockville 1 Ne station.

When is the first frost in Rockville, MD?

The median first fall frost near 20847 is November 6, giving a median frost-free growing season of 219 days.

When should I plant tomatoes in 20847?

Start tomato seeds indoors around Feb 4 – Feb 18 and set transplants outside around Apr 8 – Apr 22, one to three weeks after the median last frost.

How much rain and snow does 20847 get?

About 41.3 inches of precipitation a year (NOAA 1991–2020 normals, Rockville 1 Ne station).

How hot do summers get in Rockville, MD?

The average high peaks at 87 °F in July, with about 23 days a year at 90 °F or more.

What kind of soil does 20847 have?

The USDA soil survey maps Udorthents at the center of ZIP 20847: loam, well drained, pH about 5.8 (moderately acidic).

Did spring come early in Rockville, MD in 2026?

Spring leaf-out near 20847 came on Mar 12 in 2026, 4 days earlier than the 1991–2020 average (Mar 16), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Rockville, MD?

Intermediate onions: the longest day near 20847 is 14 h 55 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

Did the zone for 20847 change?

Yes. The 2012 USDA map put 20847 in zone 7a; the 2023 map puts it in zone 7b. The newer map uses 1991–2020 data and more weather stations.