Texas planting calendar

When to plant onions in Texas — sow, transplant & harvest dates

Texas is mostly USDA zone 8b (range 6a-10a). Dates below are derived from onions's frost tolerance and Texas's frost window — not generic national averages.

Onions planting timetable for Texas

Stage	When in Texas	Anchor
Start seeds indoors	early January (January 4)	10 weeks before the last frost (mid-March (most of state))
Transplant outside	mid-February (February 15)	28 days before the last frost (mid-March (most of state))
First harvest (estimate)	early June (June 5)	~110 days from transplant

Dates are state-wide averages for the dominant zone. Local microclimates — elevation, urban heat, coastal moderation — can shift the window by 1-2 weeks. Use the frost-date calculator for a date tuned to your town.

Why Texas's climate shifts the onions dates

Texas's last spring frost averages mid-March (most of state) and first fall frost mid-November (most of state), which sets the whole planting clock. Texas is huge and spans cold Panhandle plains to a nearly frost-free Gulf and Rio Grande Valley. Most of the state has a long, hot season in zones 8-9. Sow early — onions bolt once daytime temperatures hold above 24 °C, so the earlier they go in, the longer the harvest.

Onions are day-length sensitive: long-day varieties (zones 1–6) begin bulbing when days exceed 14 hours, short-day types (zones 7–10) bulb at 10–12 hours, and intermediate-day varieties span zones 5–6. Start seeds indoors 10–12 weeks before the last spring frost and transplant out 4–6 weeks before it — young onion seedlings tolerate frost down to about -6 °C once hardened off. In zones 8–10 a second planting from sets in autumn is common, overwintering for an early-summer harvest.

Frost-risk note

Don't plant before mid-March (most of state) — a hard freeze can still set young plants back. In the northern Panhandle near Dalhart (zone 6a) the safe date runs a week or two later.

Regional variation within Texas

the northern Panhandle near Dalhart (zone 6a) runs roughly 1-2 weeks behind the state average; the lower Rio Grande Valley near Brownsville (zone 10a) can plant 1-2 weeks earlier.

Houston — USDA zone 9b
San Antonio — USDA zone 9a
Dallas — USDA zone 8b
Austin — USDA zone 9a
El Paso — USDA zone 8b

What else to plant in Texas around then

The same early window suits peas, lettuce, spinach, and onion sets.

Quick-grow guide

Sun: Full sun — 6+ hours direct.
Soil temperature for germination: 10-35 °C (50-95 °F).
Spacing: 4-6 inches (10-15 cm) between plants.
Days to harvest: ~110 days from planting out.

Frequently asked questions

When is the best time to plant onions in Texas?

In Texas (mostly USDA zone 8b), sow onions indoors around early January, transplant outdoors mid-February (before the last frost, mid-March), and harvest from early June. Onions are cold-hardy — they tolerate frost and actively prefer cool weather, so they go in well before the last spring frost and bolt in summer heat.

What USDA zone is Texas?

Most of Texas sits in USDA hardiness zone 8b, with the state spanning roughly 6a-10a from the northern Panhandle near Dalhart (zone 6a) to the lower Rio Grande Valley near Brownsville (zone 10a). The last spring frost averages mid-March (most of state) and the first fall frost mid-November (most of state).

Can you grow onions in Texas?

Yes. Texas's dominant zone 8b supports onions — the key is timing. Onions are cold-hardy — they tolerate frost and actively prefer cool weather, so they go in well before the last spring frost and bolt in summer heat.

Does the planting date change across Texas?

the northern Panhandle near Dalhart (zone 6a) runs roughly 1-2 weeks behind the state average; the lower Rio Grande Valley near Brownsville (zone 10a) can plant 1-2 weeks earlier.

What else can I plant in Texas around the same time?

The same early window suits peas, lettuce, spinach, and onion sets.

Source and methodology

State zone spans from the USDA Plant Hardiness Zone Map (2023); frost-date averages from NOAA Climate Data Online. Hot-state two-season timing cross-checked against the UF/IFAS Florida Gardening Calendar and the University of Arizona Cooperative Extension planting calendar. Curated by the Growli editorial team.