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

Planting zone for 78621 — Elgin, TX

ZIP code 78621 (Elgin, Bastrop County) is in USDA zone 9a: the coldest winter night averages 20 to 25 °F. The median last spring frost is March 4 and the first fall frost November 24.

Where ZIP 78621 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 4

First frostNov 24

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 Elgin, 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 Elgin, TX

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostMarch 4median — 50% chance of a later frost

Safe for tender plantsMarch 23only 10% chance of frost after

First fall frostNovember 24median — 10% chance by Nov 5

Growing season264 daysfrost-free, median

A hard freeze (28 °F) usually ends around February 21 and returns around December 9.

From the NOAA station Elgin 1 N, TX — 2 miles away, elevation 594 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 78621

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Jan 21 – Feb 4

SpinachSow outdoors · Jan 21 – Feb 11

Broccoli, cabbageStart indoors · Dec 24 – Jan 7

Broccoli, cabbageTransplant · Feb 11 – Feb 25

Onion setsPlant outdoors · Feb 4 – Feb 18

PotatoesPlant outdoors · Feb 11 – Feb 25

LettuceSow outdoors · Feb 4 – Feb 18

Carrots, beetsSow outdoors · Feb 11 – Feb 25

TomatoesStart indoors · Jan 7 – Jan 21

TomatoesTransplant · Mar 11 – Mar 25

Peppers, eggplantStart indoors · Dec 24 – Jan 7

Peppers, eggplantTransplant · Mar 18 – Apr 1

BeansSow outdoors · Mar 11 – Mar 25

Sweet cornSow outdoors · Mar 11 – Mar 25

Cucumbers, squashSow outdoors · Mar 11 – Mar 25

Fall lettuce, spinachSow outdoors · Sep 29 – Oct 13

GarlicPlant cloves · Nov 10 – Dec 15

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Mar 4) and first fall frost (Nov 24) 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 78621 came on Jan 30 — 4 days later than the 1991–2020 average (Jan 26).

average
Jan 262026
Jan 30

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 Elgin, TX.

Soil in Elgin, TX

The soil mapped at the center of ZIP 78621 is Edge — fine sandy loam, well drained.

TextureFine sandy loamdrains and warms fast; dries out and needs more feeding

pH5.9moderately acidic; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter0.75%low — add compost

Hydrologic groupCwater soaks in slowly

Farmland classFarmland of statewide importanceUSDA classification

Map unit: Edge fine sandy loam, 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 78621; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Elgin, TX

Summer high96 °Faverage high, August

Winter low39 °Faverage low, January

Hot days117days a year at 90 °F or more

Freezing nights18nights a year at 32 °F or less

Growing degree days6,959base 50 °F — the season’s usable heat

Longest day14 h 06 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

Precipitation36.1 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: Elgin 1 N, TX (2 mi away); precipitation: Elgin 1 N, TX (2 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 9a.

Pflugerville, TX · 16 mi

Texas planting zones →

Questions about 78621

What planting zone is ZIP code 78621?

ZIP code 78621 (Elgin, 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 Elgin, TX?

The median last spring frost (32 °F) near 78621 is March 4; after March 23 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Elgin 1 N station.

When is the first frost in Elgin, TX?

The median first fall frost near 78621 is November 24, giving a median frost-free growing season of 264 days.

When should I plant tomatoes in 78621?

Start tomato seeds indoors around Jan 7 – Jan 21 and set transplants outside around Mar 11 – Mar 25, one to three weeks after the median last frost.

How much rain and snow does 78621 get?

About 36.1 inches of precipitation a year (NOAA 1991–2020 normals, Elgin 1 N station).

How hot do summers get in Elgin, TX?

The average high peaks at 96 °F in August, with about 117 days a year at 90 °F or more.

What kind of soil does 78621 have?

The USDA soil survey maps Edge at the center of ZIP 78621: fine sandy loam, well drained, pH about 5.9 (moderately acidic).

Did spring come early in Elgin, TX in 2026?

Spring leaf-out near 78621 came on Jan 30 in 2026, 4 days later than the 1991–2020 average (Jan 26), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Elgin, TX?

Short-day onions: the longest day near 78621 is 14 h 06 min, so summer days stay under about 14 h 20 min, so long-day varieties won’t bulb.

Did the zone for 78621 change?

Yes. The 2012 USDA map put 78621 in zone 8b; the 2023 map puts it in zone 9a. The newer map uses 1991–2020 data and more weather stations.