When to plant in Sienna, TX
USDA Zone 9bHere are the average frost dates, USDA hardiness zone, and a month-by-month planting calendar for Sienna, Texas — all computed from Sienna's nearest NOAA weather station.
Sienna enjoys a long ~294-day frost-free season — you can succession-sow, fit in a second crop, and grow long-season heat-lovers with room to spare. Zone 9b is warm enough that Sienna can grow subtropical perennials, and the short (or absent) frost period barely limits the annual calendar.
The average last spring frost in Sienna is now 9 days earlier than in the 1981–2010 normals. See how frost dates are shifting nationwide →
Frost probability
THOMPSONS 3 WSW · 1991–2020The date the last spring and first fall frost occur, by threshold and probability. A 90% date is later in spring — and earlier in fall — than a 10% date; the 50% · 32°F row is what most gardeners plan around. These are Sienna’s own odds, recorded at THOMPSONS 3 WSW.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | Apr 1 | Mar 6 | Feb 4 | Nov 4 | Nov 22 | Dec 12 |
| 32°F | Mar 15 | Feb 15 | Jan 13 | Nov 13 | Dec 6 | Jan 5 |
| 28°F | Mar 5 | Jan 26 | Dec 21 | Nov 29 | Dec 29 | Jan 29 |
Download this table as CSV ↓ — every threshold and probability, plus this city’s planting-window dates.
What to plant now
TODAY · JULY 19Nothing new to sow or transplant outdoors in the next few weeks — a seasonal lull. Check the full-year calendar below for the next window.
Full-year planting calendar
Each bar is the exact window to take a planting action in Sienna, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 21 km · complete 32°F normalsWhen stations disagree by more than a few days, that spread is real microclimate variation — elevation, water, urban heat. Judge which station best matches your own yard.
Sienna planting FAQ
When is the last spring frost in Sienna, TX?
Sienna's average last spring frost falls near February 15 — the 50% mark at 32°F in the 1991–2020 normals. Hold tender transplants until the risk has passed, then plant out.
When is the first fall frost in Sienna, TX?
The first fall frost in Sienna typically arrives around December 6 (50% probability at 32°F). Harvest or protect frost-sensitive crops before then.
What hardiness zone is Sienna in?
Sienna is in USDA hardiness zone 9b. In zone 9b, winters are mild — many tender perennials overwinter here.
How long is the growing season in Sienna?
There are roughly 294 frost-free days in Sienna (a long growing season), running from the average last frost around February 15 to the first fall frost near December 6.
When should I plant tomatoes in Sienna?
In Sienna, start tomato seeds indoors around December 21–January 4, then transplant seedlings outdoors around February 22 once the danger of frost has passed.
Never miss a window in Sienna
An email when it’s time to start seeds, transplant, and sow — timed to Sienna’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reach- Fresno · 7 km
- Missouri City · 9 km
- Iowa Colony · 9 km
- Manvel · 14 km
- Stafford · 17 km
- Sugar Land · 17 km
- Pearland · 19 km
- Bellaire · 25 km
Frost dates recorded at THOMPSONS 3 WSW, 12 km from the city center · 1991–2020 NOAA climate normals · zone from the USDA/PRISM 2023 map. How we compute this.
BlissGarden. "When to Plant in Sienna, TX — Frost Dates & Zone 9b." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USC00418996. Retrieved from https://blissgarden.com/texas/sienna.