Data: 2023 USDA zones (PRISM/OSU) · NOAA 1991–2020 normals · updated Oct 29, 2026

Planting zone for Olney, MD

Olney, MD is in USDA zone 7b across its 2 ZIP codes. The median last spring frost is April 1 and the first fall frost November 6.

Olney on the zone map

Outlined: its 1 ZIP code areas · 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

ZIP codes2

Last frostApr 1

First frostNov 6

Growing season219 days

7b 2 ZIPs

Frost forecast — next 7 nights

live from the National Weather Service

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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 Olney, 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, 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 Olney

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 20830 came on Mar 13 — 5 days earlier than the 1991–2020 average (Mar 18).

average
Mar 182026
Mar 13

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.

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 Olney, MD.

Soil in Olney, MD

The soil mapped at the center of ZIP 20830 is Glenelg — silt loam, well drained.

TextureSilt loama good balance for most vegetables

pH5.4strongly acidic; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter2.5%moderate

Hydrologic groupBwater soaks in moderately

Farmland classprime farmlandUSDA classification

Map unit: Glenelg silt loam, 3 to 8 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 20830; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Olney, 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

Precipitation48.1 inper year, rain and melted snow

Average high and low, by month

Precipitation by month inches

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Rockville 1 Ne, MD (6 mi away); precipitation: Olney 1.0 Se, MD (within 1 mile). Daylight is calculated from latitude.

ZIP codes in Olney

Maryland planting zones →

Questions about Olney

What planting zone is Olney, MD?

Olney, MD is in USDA hardiness zone 7b on the 2023 map (7b: 5 to 10 °F).

When is the last frost in Olney, MD?

The median last spring frost is April 1 and the median first fall frost is November 6 (NOAA 1991–2020 normals, Rockville 1 Ne station).

When can I plant a garden in Olney, MD?

Cool-season crops like peas and spinach go in around Feb 18 – Mar 11; tomatoes, peppers, beans and squash after about Apr 8, once frost risk has passed.

What kind of onions grow in Olney, MD?

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

How much rain and snow does Olney, MD get?

About 48.1 inches of precipitation a year (NOAA 1991–2020 normals).