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

Planting zone for 02921 — Cranston, RI

ZIP code 02921 (Cranston, Providence County) is in USDA zone 6b: the coldest winter night averages −5 to 0 °F. The median last spring frost is April 11 and the first fall frost October 30.

Where ZIP 02921 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.

Zone6b−5 to 0 °F
Coldest night−20.6 to −17.8 °C
Last frostApr 11
First frostOct 30
2012 zone6b

Same zone as on the 2012 map. The zone is the one at the center of the ZIP code; hilly ZIPs can span two zones. What zone 6b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Cranston, RI…

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 Cranston, RI

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 11median — 50% chance of a later frost
Safe for tender plantsApril 23only 10% chance of frost after
First fall frostOctober 30median — 10% chance by Oct 16
Growing season199 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 1 and returns around November 9.

From the NOAA station Providence T F Green Airport, RI — 5 miles away, elevation 59 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 02921

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Feb 28 – Mar 14
SpinachSow outdoors · Feb 28 – Mar 21
Broccoli, cabbageStart indoors · Jan 31 – Feb 14
Broccoli, cabbageTransplant · Mar 21 – Apr 4
Onion setsPlant outdoors · Mar 14 – Mar 28
PotatoesPlant outdoors · Mar 21 – Apr 4
LettuceSow outdoors · Mar 14 – Mar 28
Carrots, beetsSow outdoors · Mar 21 – Apr 4
TomatoesStart indoors · Feb 14 – Feb 28
TomatoesTransplant · Apr 18 – May 2
Peppers, eggplantStart indoors · Jan 31 – Feb 14
Peppers, eggplantTransplant · Apr 25 – May 9
BeansSow outdoors · Apr 18 – May 2
Sweet cornSow outdoors · Apr 18 – May 2
Cucumbers, squashSow outdoors · Apr 18 – May 2
Fall lettuce, spinachSow outdoors · Sep 4 – Sep 18
GarlicPlant cloves · Oct 16 – Nov 20
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 11) and first fall frost (Oct 30) 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 02921 came on Apr 3 — about the same time as the 1991–2020 average (Apr 4).

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 6b in Rhode Island

452 plants native to the lower 48 states, recorded in Rhode Island, and rated by the USDA to survive −5 °F or colder — the bottom of zone 6b. Each links to its USDA PLANTS profile.

Trees 56

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 94

Allegheny serviceberry35 ft · blooms early spring · low shade tolerance · to −38 °Falternateleaf dogwood25 ft · blooms mid spring · low shade tolerance · to −47 °FAmerican black currant3 ft · blooms early spring · to −46 °FAmerican hazelnut10 ft · blooms spring · medium shade tolerance · to −33 °FAmerican holly40 ft · blooms mid spring · low shade tolerance · to −20 °FAmerican hornbeam30 ft · blooms mid spring · low shade tolerance · to −34 °F

Wildflowers & perennials 156

alkali buttercup1 ft · blooms late spring · low shade tolerance · to −38 °Falpine sweetvetch2 ft · blooms early summer · high shade tolerance · to −62 °FAmerican bur-reed3 ft · blooms indeterminate · medium shade tolerance · to −33 °FAmerican eelgrass1 ft · blooms mid summer · high shade tolerance · to −33 °FAmerican licorice4 ft · blooms late spring · medium shade tolerance · to −38 °FAmerican pokeweed7 ft · blooms mid summer · low shade tolerance · to −33 °F

Grasses 125

American beachgrass2.5 ft · blooms spring · high shade tolerance · to −28 °FAtlantic mannagrass3 ft · blooms summer · low shade tolerance · to −8 °Fawlfruit sedge4 ft · blooms mid spring · low shade tolerance · to −38 °Fbeaked spikerush3 ft · blooms late spring · high shade tolerance · to −28 °FBicknell's sedge3 ft · blooms late spring · low shade tolerance · to −38 °Fbig bluestem6 ft · blooms summer · high shade tolerance · to −46 °F

Vines 7

American bittersweet15 ft · blooms spring · low shade tolerance · to −38 °Fdevil's darning needles15 ft · blooms mid summer · medium shade tolerance · to −38 °Friverbank grape45 ft · blooms late spring · medium shade tolerance · to −33 °Fsummer grape30 ft · blooms late spring · low shade tolerance · to −23 °Ftrumpet creeper2 ft · blooms summer · high shade tolerance · to −13 °Ftrumpet honeysuckle16 ft · blooms late summer · low shade tolerance · to −33 °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 Cranston, RI.

Soil in Cranston, RI

The soil mapped at the center of ZIP 02921 is Woodbridge — fine sandy loam, moderately well drained.

TextureFine sandy loamdrains and warms fast; dries out and needs more feeding
pH5.2strongly acidic; most vegetables like 6.0–7.0
DrainageModerately well drainednatural drainage class
Organic matter5.5%high
Hydrologic groupC/Dslow when drained; wet otherwise
Farmland classprime farmlandUSDA classification

Map unit: Woodbridge fine sandy loam, 0 to 3 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 02921; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Cranston, RI

Summer high84 °Faverage high, July
Winter low22 °Faverage low, January
Hot days12days a year at 90 °F or more
Freezing nights109nights a year at 32 °F or less
Growing degree days3,090base 50 °F — the season’s usable heat
Longest day15 h 13 mindaylight on June 21
Shortest day9 h 08 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation47.5 inper year, rain and melted snow
Snowfall37 inper year; 25 days with snow on the ground

Average high and low, by month

10°20°30°40°50°60°70°80°90°32 °FJanuary: average high 38 °F, low 22 °F 38°22° JanFebruary: average high 41 °F, low 24 °F 41°24° FebMarch: average high 48 °F, low 30 °F 48°30° MarApril: average high 59 °F, low 40 °F 59°40° AprMay: average high 69 °F, low 49 °F 69°49° MayJune: average high 78 °F, low 59 °F 78°59° JunJuly: average high 84 °F, low 65 °F 84°65° JulAugust: average high 82 °F, low 64 °F 82°64° AugSeptember: average high 75 °F, low 57 °F 75°57° SepOctober: average high 64 °F, low 45 °F 64°45° OctNovember: average high 53 °F, low 36 °F 53°36° NovDecember: average high 43 °F, low 28 °F 43°28° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″4″5″January: 3.96 in precipitation, 10.3 in snowfall 4.0❄10 JanFebruary: 3.44 in precipitation, 10.5 in snowfall 3.4❄11 FebMarch: 4.90 in precipitation, 6.4 in snowfall 4.9❄6 MarApril: 4.29 in precipitation, 0.6 in snowfall 4.3❄1 AprMay: 3.37 in precipitation 3.4 MayJune: 3.81 in precipitation 3.8 JunJuly: 2.91 in precipitation 2.9 JulAugust: 3.59 in precipitation 3.6 AugSeptember: 4.17 in precipitation 4.2 SepOctober: 4.18 in precipitation, 0.2 in snowfall 4.2 OctNovember: 4.27 in precipitation, 1 in snowfall 4.3❄1 NovDecember: 4.65 in precipitation, 7.6 in snowfall 4.7❄8 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Providence T F Green Airport, RI (5 mi away); precipitation: Providence T F Green Airport, RI (5 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.

028236b
Fiskeville, RI · 3 mi
029207a
Cranston, RI · 3 mi
028316b
Hope, RI · 4 mi
029107a
Cranston, RI · 4 mi
029196b
Johnston, RI · 4 mi
029097a
Providence, RI · 5 mi
028867a
Warwick, RI · 5 mi
029077a
Providence, RI · 5 mi

All 3 ZIP codes in Cranston → · Rhode Island planting zones →

Questions about 02921

What planting zone is ZIP code 02921?

ZIP code 02921 (Cranston, RI) is in USDA hardiness zone 6b on the 2023 map: the coldest night of an average winter reaches −5 to 0 °F (−20.6 to −17.8 °C).

When is the last frost in Cranston, RI?

The median last spring frost (32 °F) near 02921 is April 11; after April 23 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Providence T F Green Airport station.

When is the first frost in Cranston, RI?

The median first fall frost near 02921 is October 30, giving a median frost-free growing season of 199 days.

When should I plant tomatoes in 02921?

Start tomato seeds indoors around Feb 14 – Feb 28 and set transplants outside around Apr 18 – May 2, one to three weeks after the median last frost.

How much rain and snow does 02921 get?

About 47.5 inches of precipitation a year and 37 inches of snowfall (NOAA 1991–2020 normals, Providence T F Green Airport station).

How hot do summers get in Cranston, RI?

The average high peaks at 84 °F in July, with about 12 days a year at 90 °F or more.

What kind of soil does 02921 have?

The USDA soil survey maps Woodbridge at the center of ZIP 02921: fine sandy loam, moderately well drained, pH about 5.2 (strongly acidic).

Did spring come early in Cranston, RI in 2026?

Spring leaf-out near 02921 came on Apr 3 in 2026, about the same as the 1991–2020 average (Apr 4), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Cranston, RI?

Long-day onions: the longest day near 02921 is 15 h 13 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).