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TableEntry 36Reviewed 2026-10-16

USDA zone 9

Zone 9 means an average yearly winter low of 20 to 30°F. At the six zone 9 cities on this page, from New Orleans to Seattle, median freeze dates fall between late November and mid-March, and extension guides put lettuce, broccoli and other cool-season crops in fall and winter. The same zone still covers very different winters.

What zone 9 means

USDA's Plant Hardiness Zone Map "is based on the average annual extreme minimum winter temperature, displayed as 10-degree F zones and 5-degree F half zones" (USDA ARS). USDA's ZIP code search labels the two halves of zone 9 like this:

Half zoneAverage annual extreme minimum (°F)(°C)
9a20 to 25−6.7 to −3.9
9b25 to 30−3.9 to −1.1

On the 2023 map, zone 9 includes Houston, New Orleans, Tucson and Sacramento (9b), and Tallahassee, San Antonio, Charleston and Seattle (9a). Inside one metro area the half zone can change: downtown Tucson (85701) is 9b, while ZIP 85756 on the city's south side is 9a. For your own address, use the ZIP search on USDA's map; every zone on this page was checked that way in October 2026.

Zone 9 does not set your frost dates

USDA describes the map as the standard for deciding "which perennial plants are most likely to thrive at a location." Freeze dates come from NOAA's Climate Normals, which give the first fall and last spring 32°F freeze at stated probabilities and the chance of reaching 32°F at all in a year; in zone 9 some winters pass without a freeze. The hardiness zones guide explains the difference, and frost dates explained shows where to look up your nearest station.

Six zone 9 cities, side by side

Zone: USDA ZIP search, city ZIP shown (2023 map, 2012 in brackets). Freeze data: NOAA NCEI 1991–2020 normals, 32°F, at the stations named below the table. The 50% date is the median; a 10% fall date means a freeze that early about 1 year in 10, and a 10% spring date a later freeze about 1 year in 10 (NC State's guide to these tables). "Any 32°F night" is NOAA's probability that the temperature drops to 32°F or lower at least once in a year.

Place (ZIP)Zone 2023 (2012)First fall freeze 50% (10%)Last spring freeze 50% (10%)Freeze-free season, days 50% (90%)Any 32°F night
New Orleans, LA (70112)9b (9b)Dec 31 (Dec 1)Jan 30 (Feb 27)333 (296)86.8% of years
Tucson, AZ (85701)9b (9b)Dec 9 (Nov 21)Feb 5 (Mar 2)307 (274)98.9%
Sacramento, CA (95814)9b (9b)Dec 2 (Nov 16)Feb 2 (Mar 5)301 (266)98.1%
Houston, TX (77002)9b (9a)Dec 9 (Nov 17)Feb 13 (Mar 12)300 (264)98.9%
Seattle, WA (98101)9a (8b)Nov 23 (Nov 6)Mar 2 (Mar 23)266 (239)100%
Tallahassee, FL (32301)9a (8b)Nov 21 (Nov 3)Mar 11 (Mar 30)255 (226)100%

Stations: New Orleans Intl AP, Tucson Intl AP, Sacramento Executive AP, Houston Intercont AP, Seattle Tacoma Intl AP, Tallahassee. NC State calls the 90% season the conservative one: at least that long in about 9 years out of 10.

What the table shows:

Winter freeze window at six USDA zone 9 places, NOAA 1991–2020 normals, with cool-season planting windows from UF/IFAS, Texas A&M and UC Master Gardeners of Sacramento CountyAn August to April timeline. Top part: one row per place, longest freeze-free season first: New Orleans (zone 9b), Tucson (9b), Sacramento (9b), Houston (9b), Seattle (9a) and Tallahassee (9a). A dark blue bar runs from the 50 percent date of the first fall 32 degree freeze to the 50 percent date of the last spring freeze; a lighter band extends it to the 10 percent dates. The bars widen from about one month in New Orleans (December 31 to January 30) to almost four months in Tallahassee (November 21 to March 11). A right-hand column gives NOAA's median freeze-free season: 333, 307, 301, 300, 266 and 255 days. New Orleans is marked with an 86.8 percent yearly chance of any 32 degree night. Bottom part: six green bars on the same time axis show planting windows: UF/IFAS North Florida broccoli September to February, spinach October to November and lettuce February to March; Texas A&M broccoli average date October 1 to last optimum October 20 in Region IV (USDA 9a) and November 1 to November 20 in Region V (9b); Sacramento Valley garlic September to mid December. Six numbered markers match the list below the drawing. Winter freeze window (32°F), NOAA NCEI normals 1991–2020 AugSepOctNovDecJanFebMarApr Season New Orleans, LA 9b 333 d Tucson, AZ 9b 307 d Sacramento, CA 9b 301 d Houston, TX 9b 300 d Seattle, WA 9a 266 d Tallahassee, FL 9a 255 d any 32°F night: 86.8% of years Cool-season planting windows in three extension guides Broccoli, North FL Sep–Feb (UF/IFAS) Spinach, North FL Oct–Nov (UF/IFAS) Lettuce, North FL Feb–Mar (UF/IFAS) Broccoli, TX Region IV Oct 1–20 (Texas A&M) Broccoli, TX Region V Nov 1–20 (Texas A&M) Garlic, Sacramento Valley Sep–mid Dec (UC MG) 50% first fall to 50% last spring freeze out to the 10% dates planting window (seed or transplants, as the guide states) 123456
Drawing by The More One Sows, based on the cited sources. Dates as in the tables on this page. Not to scale vertically; the time axis is to scale.
  • 1. Half zone from USDA's ZIP search for the city ZIP (2023 map): New Orleans, Tucson, Sacramento and Houston are 9b; Seattle and Tallahassee are 9a
  • 2. Dark blue bar: from the 50% first fall 32°F freeze to the 50% last spring freeze (NOAA NCEI 1991–2020), the median freeze window
  • 3. Light band: out to the 10% dates, when an earlier fall or later spring freeze happens about 1 year in 10
  • 4. NOAA's median freeze-free season: 333 days in New Orleans down to 255 in Tallahassee; the two 9a places have the shortest
  • 5. New Orleans: NOAA gives an 86.8% chance of any 32°F night in a year; Seattle and Tallahassee 100%
  • 6. Green bars: planting windows from UF/IFAS (North Florida broccoli Sept–Feb, spinach Oct–Nov, lettuce Feb–Mar), Texas A&M (broccoli average date to last optimum date: Region IV Oct 1–20, Region V Nov 1–20) and UC Master Gardeners of Sacramento County (garlic September to mid December)

Fall and winter: the main vegetable season

Texas A&M AgriLife's fall guide (Stein and Masabni) matches its Texas gardening Region IV to USDA zone 9a and Region V to zone 9b in its Table 3, so those two columns are zone 9 columns. UF/IFAS's Florida Vegetable Gardening Guide splits the state at State Roads 40 and 70; Tallahassee lies in its North region.

CropTexas Region IV, 9a (average date)Texas Region V, 9b (average date)North Florida (UF/IFAS)Central Florida (UF/IFAS)
BroccoliOct 1; last optimum Oct 20Nov 1; last optimum Nov 20Sept–FebSept–Feb
CabbageOct 1; last optimum Oct 20Nov 1; last optimum Nov 20Sept–FebSept–Feb
CarrotsNov 20Dec 15Sept–MarAug–Mar
CollardsOct 20Dec 15Feb–Apr and Sept–NovSept–Feb
LettuceLeaf Nov 1Leaf Dec 1Feb–MarSept–Feb
SpinachDec 1Dec 15Oct–NovSept–Mar
BeetsNov 1Dec 15Sept–MarSept–Feb
RadishesDec 1Dec 15Sept–MarSept–Mar
OnionsSeed Dec 1Seed Dec 15Bulbing Sept–DecBulbing Oct
English or snow peasNot listedNot listedJan–MarNov–Feb
Tomatoes (fall crop)July 10; last optimum Aug 10Aug 1; last optimum Sept 1Aug (and late Mar–Apr)Aug–Sept (and Jan–Feb)

Texas dates are from its average fall planting date table, with "last optimum" dates from its Table 2 where it gives one; garlic cloves go in during November (Region IV) or December (Region V). UF/IFAS gives outdoor planting months.

Two western guides describe the same season in words rather than dates:

What the guides add:

Crop pages with container sizes: lettuce, spinach, kale, carrots, radishes, peas.

Where the sources disagree

QuestionWhat the sources say
When to plant lettuceUF/IFAS: February–March in North Florida but September–February in Central Florida. Texas A&M: leaf lettuce November 1 (9a) and December 1 (9b). Pima County: September, by mid-month, and early October. Sacramento: February from seed.
Frost in Tucson in OctoberPima County's October guide warns of "the potential for frost late in the month." NOAA's Tucson airport station gives a 10% first-freeze date of November 21 and a median of December 9. The guide covers all of Pima County, not one station.
What 9a or 9b says about winterSeattle and Tallahassee are both 9a, each with NOAA's 100% chance of a 32°F night, but their median last freezes are 9 days apart. New Orleans and Sacramento are both 9b; New Orleans has the lower chance of any 32°F night (86.8% against 98.1%).

Using this page in a zone 9 garden

  1. Confirm your half zone with USDA's ZIP search; Houston, Seattle and Tallahassee moved up a half zone between the 2012 and 2023 maps.
  2. Use the zone for perennials; that is what USDA designed the map for.
  3. Get freeze dates for the station nearest you (see how to find your frost dates), then enter them in the planting calendar.
  4. Check how often your station freezes at all; in New Orleans some winters pass without a 32°F night, in Tallahassee NOAA puts the chance of a 32°F night at 100%.
  5. Plan the cool season in late summer: Pima County starts brassica seedlings in September, and Texas A&M's Region IV broccoli date is October 1.
  6. Use your state or county guide for crop dates; the guides above differ by months. The zone 8 page compares six cities one zone colder.
Each NOAA station describes its own spot; a garden in a valley, on a slope or near a city center can differ.

Sources

  1. USDA Agricultural Research Service — USDA Plant Hardiness Zone Map (interactive map and ZIP code search)
  2. NOAA NCEI — Access Data Service: U.S. Climate Normals 1991–2020, annual/seasonal 32°F freeze dates, growing season and freeze probabilities for the six zone 9 stations named on this page (CSV)
  3. NOAA NCEI — Readme for the 1991–2020 normals files (definitions of PRBLST, PRBFST and PRBGSL)
  4. NC State Extension — Interpreting Freeze/Frost Probabilities from the National Centers for Environmental Information (AG-873)
  5. UF/IFAS Extension — Florida Vegetable Gardening Guide (SP 103/VH021, Park-Brown, Saracino, Williams and Treadwell)
  6. Texas A&M AgriLife Extension — Fall Vegetable Gardening Guide for Texas (Larry Stein and Joe Masabni)
  7. UC Agriculture and Natural Resources — UC Master Gardeners of Sacramento County: Monthly Vegetable Gardening Tips
  8. University of Arizona Cooperative Extension — September Monthly Gardening Guide for Pima County (Vance, Larson and North, 2025)
  9. University of Arizona Cooperative Extension — October Monthly Gardening Guide for Pima County (Larson, Vance and North, 2025)

All sources were opened and checked in October 2026. Rules and figures change; confirm with the original before acting.

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