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

Planting zone for 22172 — Triangle, VA

ZIP code 22172 (Triangle, Prince William County) is in USDA zone 7a: the coldest winter night averages 0 to 5 °F. The median last spring frost is March 28 and the first fall frost November 8.

Where ZIP 22172 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.

Zone7a0 to 5 °F

Coldest night−17.8 to −15 °C

Last frostMar 28

First frostNov 8

2012 zone7b

Was 7b on the 2012 map — half a zone colder now. The zone is the one at the center of the ZIP code; hilly ZIPs can span two zones. What zone 7a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Triangle, VA…

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 Triangle, VA

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostMarch 28median — 50% chance of a later frost

Safe for tender plantsApril 8only 10% chance of frost after

First fall frostNovember 8median — 10% chance by Oct 28

Growing season226 daysfrost-free, median

A hard freeze (28 °F) usually ends around March 17 and returns around November 22.

From the NOAA station Quantico Mcas, VA — 7 miles away, elevation 10 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 22172

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Feb 14 – Feb 28

SpinachSow outdoors · Feb 14 – Mar 7

Broccoli, cabbageStart indoors · Jan 17 – Jan 31

Broccoli, cabbageTransplant · Mar 7 – Mar 21

Onion setsPlant outdoors · Feb 28 – Mar 14

PotatoesPlant outdoors · Mar 7 – Mar 21

LettuceSow outdoors · Feb 28 – Mar 14

Carrots, beetsSow outdoors · Mar 7 – Mar 21

TomatoesStart indoors · Jan 31 – Feb 14

TomatoesTransplant · Apr 4 – Apr 18

Peppers, eggplantStart indoors · Jan 17 – Jan 31

Peppers, eggplantTransplant · Apr 11 – Apr 25

BeansSow outdoors · Apr 4 – Apr 18

Sweet cornSow outdoors · Apr 4 – Apr 18

Cucumbers, squashSow outdoors · Apr 4 – Apr 18

Fall lettuce, spinachSow outdoors · Sep 13 – Sep 27

GarlicPlant cloves · Oct 25 – Nov 29

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Mar 28) and first fall frost (Nov 8) 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 22172 came on Mar 10 — about the same time as the 1991–2020 average (Mar 12).

average
Mar 122026
Mar 10

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 7a in Virginia

618 plants native to the lower 48 states, recorded in Virginia, and rated by the USDA to survive 0 °F or colder — the bottom of zone 7a. 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 Triangle, VA.

Soil in Triangle, VA

The soil mapped at the center of ZIP 22172 is Occoquan — sandy loam, well drained.

TextureSandy loamdrains and warms fast; dries out and needs more feeding

pH4.6strongly acidic; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter1.25%low — add compost

Hydrologic groupAwater soaks in fast

Farmland classNot prime farmlandUSDA classification

Map unit: Occoquan sandy loam, 25 to 50 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 22172; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Triangle, VA

Summer high88 °Faverage high, July

Winter low28 °Faverage low, January

Hot days30days a year at 90 °F or more

Freezing nights76nights a year at 32 °F or less

Growing degree days4,379base 50 °F — the season’s usable heat

Longest day14 h 52 mindaylight on June 21

Shortest day9 h 28 mindaylight on December 21

Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully

Precipitation47.8 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: Quantico Mcas, VA (7 mi away); precipitation: Manassas 5.8 Se, VA (7 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

Woodbridge, VA · 5 mi

Woodbridge, VA · 8 mi

224637a

Garrisonville, VA · 8 mi

Virginia planting zones →

Questions about 22172

What planting zone is ZIP code 22172?

ZIP code 22172 (Triangle, VA) is in USDA hardiness zone 7a on the 2023 map: the coldest night of an average winter reaches 0 to 5 °F (−17.8 to −15 °C).

When is the last frost in Triangle, VA?

The median last spring frost (32 °F) near 22172 is March 28; after April 8 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Quantico Mcas station.

When is the first frost in Triangle, VA?

The median first fall frost near 22172 is November 8, giving a median frost-free growing season of 226 days.

When should I plant tomatoes in 22172?

Start tomato seeds indoors around Jan 31 – Feb 14 and set transplants outside around Apr 4 – Apr 18, one to three weeks after the median last frost.

How much rain and snow does 22172 get?

About 47.8 inches of precipitation a year (NOAA 1991–2020 normals, Manassas 5.8 Se station).

How hot do summers get in Triangle, VA?

The average high peaks at 88 °F in July, with about 30 days a year at 90 °F or more.

What kind of soil does 22172 have?

The USDA soil survey maps Occoquan at the center of ZIP 22172: sandy loam, well drained, pH about 4.6 (strongly acidic).

Did spring come early in Triangle, VA in 2026?

Spring leaf-out near 22172 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 Triangle, VA?

Intermediate onions: the longest day near 22172 is 14 h 52 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

Did the zone for 22172 change?

Yes. The 2012 USDA map put 22172 in zone 7b; the 2023 map puts it in zone 7a. The newer map uses 1991–2020 data and more weather stations.