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

Planting zone for 77303 — Conroe, TX

ZIP code 77303 (Conroe, Montgomery County) is in USDA zone 9a: the coldest winter night averages 20 to 25 °F. The median last spring frost is March 11 and the first fall frost November 19.

Where ZIP 77303 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.

Zone9a20 to 25 °F

Coldest night−6.7 to −3.9 °C

Last frostMar 11

First frostNov 19

2012 zone8b

Was 8b 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 9a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Conroe, TX…

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 Conroe, TX

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostMarch 11median — 50% chance of a later frost

Safe for tender plantsApril 3only 10% chance of frost after

First fall frostNovember 19median — 10% chance by Nov 1

Growing season253 daysfrost-free, median

A hard freeze (28 °F) usually ends around February 21 and returns around December 4.

From the NOAA station Conroe Montgomery Co. Airport, TX — 2 miles away, elevation 246 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 77303

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Jan 28 – Feb 11

SpinachSow outdoors · Jan 28 – Feb 18

Broccoli, cabbageStart indoors · Dec 31 – Jan 14

Broccoli, cabbageTransplant · Feb 18 – Mar 4

Onion setsPlant outdoors · Feb 11 – Feb 25

PotatoesPlant outdoors · Feb 18 – Mar 4

LettuceSow outdoors · Feb 11 – Feb 25

Carrots, beetsSow outdoors · Feb 18 – Mar 4

TomatoesStart indoors · Jan 14 – Jan 28

TomatoesTransplant · Mar 18 – Apr 1

Peppers, eggplantStart indoors · Dec 31 – Jan 14

Peppers, eggplantTransplant · Mar 25 – Apr 8

BeansSow outdoors · Mar 18 – Apr 1

Sweet cornSow outdoors · Mar 18 – Apr 1

Cucumbers, squashSow outdoors · Mar 18 – Apr 1

Fall lettuce, spinachSow outdoors · Sep 24 – Oct 8

GarlicPlant cloves · Nov 5 – Dec 10

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Mar 11) and first fall frost (Nov 19) 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 77303 came on Jan 15 — 11 days earlier than the 1991–2020 average (Jan 26).

average
Jan 262026
Jan 15

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 9a in Texas

640 plants native to the lower 48 states, recorded in Texas, and rated by the USDA to survive 20 °F or colder — the bottom of zone 9a. 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 Conroe, TX.

Soil in Conroe, TX

The soil mapped at the center of ZIP 77303 is Boy — fine sand, moderately well drained.

TextureFine sanddrains and warms fast; dries out and needs more feeding

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

DrainageModerately well drainednatural drainage class

Organic matter1.25%low — add compost

Hydrologic groupAwater soaks in fast

Farmland classNot prime farmlandUSDA classification

Map unit: Boy loamy fine sand, 1 to 5 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 77303; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Conroe, TX

Summer high95 °Faverage high, August

Winter low39 °Faverage low, January

Hot days108days a year at 90 °F or more

Freezing nights27nights a year at 32 °F or less

Growing degree days6,776base 50 °F — the season’s usable heat

Longest day14 h 07 mindaylight on June 21

Shortest day10 h 11 mindaylight on December 21

Onions to growShort-daysummer days stay under about 14 h 20 min, so long-day varieties won’t bulb

Precipitation47.6 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: Conroe Montgomery Co. Airport, TX (2 mi away); precipitation: Conroe Montgomery Co. Airport, TX (2 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 9a.

Cleveland, TX · 11 mi

All 8 ZIP codes in Conroe → · Texas planting zones →

Questions about 77303

What planting zone is ZIP code 77303?

ZIP code 77303 (Conroe, TX) is in USDA hardiness zone 9a on the 2023 map: the coldest night of an average winter reaches 20 to 25 °F (−6.7 to −3.9 °C).

When is the last frost in Conroe, TX?

The median last spring frost (32 °F) near 77303 is March 11; after April 3 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Conroe Montgomery Co. Airport station.

When is the first frost in Conroe, TX?

The median first fall frost near 77303 is November 19, giving a median frost-free growing season of 253 days.

When should I plant tomatoes in 77303?

Start tomato seeds indoors around Jan 14 – Jan 28 and set transplants outside around Mar 18 – Apr 1, one to three weeks after the median last frost.

How much rain and snow does 77303 get?

About 47.6 inches of precipitation a year (NOAA 1991–2020 normals, Conroe Montgomery Co. Airport station).

How hot do summers get in Conroe, TX?

The average high peaks at 95 °F in August, with about 108 days a year at 90 °F or more.

What kind of soil does 77303 have?

The USDA soil survey maps Boy at the center of ZIP 77303: fine sand, moderately well drained, pH about 4.6 (strongly acidic).

Did spring come early in Conroe, TX in 2026?

Spring leaf-out near 77303 came on Jan 15 in 2026, 11 days earlier than the 1991–2020 average (Jan 26), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Conroe, TX?

Short-day onions: the longest day near 77303 is 14 h 07 min, so summer days stay under about 14 h 20 min, so long-day varieties won’t bulb.

Did the zone for 77303 change?

Yes. The 2012 USDA map put 77303 in zone 8b; the 2023 map puts it in zone 9a. The newer map uses 1991–2020 data and more weather stations.