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

Planting zone for 21036 — Dayton, MD

ZIP code 21036 (Dayton, Howard County) is in USDA zone 7b: the coldest winter night averages 5 to 10 °F. The median last spring frost is April 5 and the first fall frost November 9.

Where ZIP 21036 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 5

First frostNov 9

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 Dayton, 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 Dayton, MD

JanFebMarAprMayJunJulAugSepOctNovDec

Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free

Last spring frostApril 5median — 50% chance of a later frost

Safe for tender plantsApril 19only 10% chance of frost after

First fall frostNovember 9median — 10% chance by Oct 27

Growing season218 daysfrost-free, median

A hard freeze (28 °F) usually ends around March 25 and returns around November 21.

From the NOAA station Laurel 3 W, MD — 12 miles away, elevation 400 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 21036

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Feb 22 – Mar 8

SpinachSow outdoors · Feb 22 – Mar 15

Broccoli, cabbageStart indoors · Jan 25 – Feb 8

Broccoli, cabbageTransplant · Mar 15 – Mar 29

Onion setsPlant outdoors · Mar 8 – Mar 22

PotatoesPlant outdoors · Mar 15 – Mar 29

LettuceSow outdoors · Mar 8 – Mar 22

Carrots, beetsSow outdoors · Mar 15 – Mar 29

TomatoesStart indoors · Feb 8 – Feb 22

TomatoesTransplant · Apr 12 – Apr 26

Peppers, eggplantStart indoors · Jan 25 – Feb 8

Peppers, eggplantTransplant · Apr 19 – May 3

BeansSow outdoors · Apr 12 – Apr 26

Sweet cornSow outdoors · Apr 12 – Apr 26

Cucumbers, squashSow outdoors · Apr 12 – Apr 26

Fall lettuce, spinachSow outdoors · Sep 14 – Sep 28

GarlicPlant cloves · Oct 26 – Nov 30

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 5) and first fall frost (Nov 9) 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 21036 came on Mar 13 — 6 days earlier than the 1991–2020 average (Mar 19).

average
Mar 192026
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 Dayton, MD.

Soil in Dayton, MD

The soil mapped at the center of ZIP 21036 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 21036; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Dayton, MD

Summer high89 °Faverage high, July

Winter low26 °Faverage low, January

Hot days36days a year at 90 °F or more

Freezing nights86nights a year at 32 °F or less

Growing degree days4,262base 50 °F — the season’s usable heat

Longest day14 h 56 mindaylight on June 21

Shortest day9 h 24 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: Laurel 3 W, MD (12 mi away); precipitation: Olney 1.0 Se, MD (7 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 7b.

217377b

Glenelg, MD · 1 mi

210297b

Clarksville, MD · 3 mi

217387b

Glenwood, MD · 3 mi

208337b

Brookeville, MD · 3 mi

210417b

Ellicott City, MD · 3 mi

211507b

Simpsonville, MD · 3 mi

Maryland planting zones →

Questions about 21036

What planting zone is ZIP code 21036?

ZIP code 21036 (Dayton, 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 Dayton, MD?

The median last spring frost (32 °F) near 21036 is April 5; after April 19 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Laurel 3 W station.

When is the first frost in Dayton, MD?

The median first fall frost near 21036 is November 9, giving a median frost-free growing season of 218 days.

When should I plant tomatoes in 21036?

Start tomato seeds indoors around Feb 8 – Feb 22 and set transplants outside around Apr 12 – Apr 26, one to three weeks after the median last frost.

How much rain and snow does 21036 get?

About 48.1 inches of precipitation a year (NOAA 1991–2020 normals, Olney 1.0 Se station).

How hot do summers get in Dayton, MD?

The average high peaks at 89 °F in July, with about 36 days a year at 90 °F or more.

What kind of soil does 21036 have?

The USDA soil survey maps Manor at the center of ZIP 21036: loam, well drained, pH about 5.3 (strongly acidic).

Did spring come early in Dayton, MD in 2026?

Spring leaf-out near 21036 came on Mar 13 in 2026, 6 days earlier than the 1991–2020 average (Mar 19), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Dayton, MD?

Intermediate onions: the longest day near 21036 is 14 h 56 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

Did the zone for 21036 change?

Yes. The 2012 USDA map put 21036 in zone 7a; the 2023 map puts it in zone 7b. The newer map uses 1991–2020 data and more weather stations.