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

Planting zone for 21050 — Forest Hill, MD

ZIP code 21050 (Forest Hill, Harford County) is in USDA zone 7b: the coldest winter night averages 5 to 10 °F. The median last spring frost is April 3 and the first fall frost November 6.

Where ZIP 21050 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 3
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 Forest Hill, 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 Forest Hill, MD

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 3median — 50% chance of a later frost
Safe for tender plantsApril 18only 10% chance of frost after
First fall frostNovember 6median — 10% chance by Oct 26
Growing season217 daysfrost-free, median

A hard freeze (28 °F) usually ends around March 24 and returns around November 17.

From the NOAA station Conowingo Dam, MD — 12 miles away, elevation 39 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 21050

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Feb 20 – Mar 6
SpinachSow outdoors · Feb 20 – Mar 13
Broccoli, cabbageStart indoors · Jan 23 – Feb 6
Broccoli, cabbageTransplant · Mar 13 – Mar 27
Onion setsPlant outdoors · Mar 6 – Mar 20
PotatoesPlant outdoors · Mar 13 – Mar 27
LettuceSow outdoors · Mar 6 – Mar 20
Carrots, beetsSow outdoors · Mar 13 – Mar 27
TomatoesStart indoors · Feb 6 – Feb 20
TomatoesTransplant · Apr 10 – Apr 24
Peppers, eggplantStart indoors · Jan 23 – Feb 6
Peppers, eggplantTransplant · Apr 17 – May 1
BeansSow outdoors · Apr 10 – Apr 24
Sweet cornSow outdoors · Apr 10 – Apr 24
Cucumbers, squashSow outdoors · Apr 10 – Apr 24
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 3) 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 21050 came on Mar 15 — 6 days earlier than the 1991–2020 average (Mar 21).

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 Forest Hill, MD

The soil mapped at the center of ZIP 21050 is Manor — loam, well drained.

TextureLoama good balance for most vegetables
pH5.3strongly acidic; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter3%moderate
Hydrologic groupBwater soaks in moderately
Farmland classFarmland of statewide importanceUSDA classification

Map unit: Manor loam, 8 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 21050; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Forest Hill, MD

Summer high88 °Faverage high, July
Winter low25 °Faverage low, January
Hot days37days a year at 90 °F or more
Freezing nights106nights a year at 32 °F or less
Growing degree days3,882base 50 °F — the season’s usable heat
Longest day14 h 58 mindaylight on June 21
Shortest day9 h 22 mindaylight on December 21
Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully
Precipitation50.5 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 40 °F, low 25 °F 40°25° JanFebruary: average high 43 °F, low 26 °F 43°26° FebMarch: average high 51 °F, low 34 °F 51°34° MarApril: average high 64 °F, low 44 °F 64°44° AprMay: average high 74 °F, low 54 °F 74°54° MayJune: average high 83 °F, low 64 °F 83°64° JunJuly: average high 88 °F, low 69 °F 88°69° JulAugust: average high 85 °F, low 67 °F 85°67° AugSeptember: average high 79 °F, low 60 °F 79°60° SepOctober: average high 67 °F, low 48 °F 67°48° OctNovember: average high 55 °F, low 37 °F 55°37° NovDecember: average high 45 °F, low 31 °F 45°31° Dec

Precipitation by month inches

0″1″2″3″4″5″6″January: 3.50 in precipitation 3.5 JanFebruary: 2.84 in precipitation 2.8 FebMarch: 4.27 in precipitation 4.3 MarApril: 3.62 in precipitation 3.6 AprMay: 4.44 in precipitation 4.4 MayJune: 4.64 in precipitation 4.6 JunJuly: 5.59 in precipitation 5.6 JulAugust: 4.49 in precipitation 4.5 AugSeptember: 5.27 in precipitation 5.3 SepOctober: 4.48 in precipitation 4.5 OctNovember: 3.46 in precipitation 3.5 NovDecember: 3.94 in precipitation 3.9 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Conowingo Dam, MD (12 mi away); precipitation: Kingsville 2.5 Nne, MD (7 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

210147b
Bel Air, MD · 4 mi
210847a
Jarrettsville, MD · 4 mi
210477b
Fallston, MD · 5 mi
211547a
Street, MD · 5 mi
210187b
Benson, MD · 5 mi
210157b
Bel Air, MD · 6 mi
210137b
Baldwin, MD · 7 mi
210287a
Churchville, MD · 8 mi

Maryland planting zones →

Questions about 21050

What planting zone is ZIP code 21050?

ZIP code 21050 (Forest Hill, 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 Forest Hill, MD?

The median last spring frost (32 °F) near 21050 is April 3; after April 18 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Conowingo Dam station.

When is the first frost in Forest Hill, MD?

The median first fall frost near 21050 is November 6, giving a median frost-free growing season of 217 days.

When should I plant tomatoes in 21050?

Start tomato seeds indoors around Feb 6 – Feb 20 and set transplants outside around Apr 10 – Apr 24, one to three weeks after the median last frost.

How much rain and snow does 21050 get?

About 50.5 inches of precipitation a year (NOAA 1991–2020 normals, Kingsville 2.5 Nne station).

How hot do summers get in Forest Hill, MD?

The average high peaks at 88 °F in July, with about 37 days a year at 90 °F or more.

What kind of soil does 21050 have?

The USDA soil survey maps Manor at the center of ZIP 21050: loam, well drained, pH about 5.3 (strongly acidic).

Did spring come early in Forest Hill, MD in 2026?

Spring leaf-out near 21050 came on Mar 15 in 2026, 6 days earlier than the 1991–2020 average (Mar 21), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Forest Hill, MD?

Intermediate onions: the longest day near 21050 is 14 h 58 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

Did the zone for 21050 change?

Yes. The 2012 USDA map put 21050 in zone 7a; the 2023 map puts it in zone 7b. The newer map uses 1991–2020 data and more weather stations.