PlantAlong

When to plant lettuce in zone 8b

Transplant outdoors around Mar 3. That is 2 weeks before zone 8b's median last frost, Mar 171. Across most of zone 8b that date falls between Feb 21 and Mar 18.

Why a range: zone 8b is defined by winter lows, not frost dates. Its ZIP codes have median last frosts from Mar 6 to Apr 12, so a single zone date can be weeks off for you. The rule comes from Oregon State University Extension Service.

Last reviewed
Stations
652
ZIP codes
2,535
Photo: Zoran Milosavljevic / Pexels
These dates use the typical last frost for the whole zone. Your ZIP code gives a closer answer.
  1. Start indoorsOregon State, central OR
  2. Transplant outdoorsOregon State, central OR
  3. Sow outdoorsColorado State
  • Start indoors
  • Plant outdoors
  • Range across the zone
  • Frost-free season (median)
  • Spring frost risk (90% to 10%)
  • Fall frost risk (10% to 90%)
Figure 1. Lettuce in zone 8b. Dark bars: at the zone's median frost dates. Pale bars: across most of the zone's ZIP codes. Hatched blue: where the zone's last and first frosts fall.
Start seeds indoors
Jan 287 weeks before last frost (Oregon State, central OR)
Transplant outdoors
Mar 3range Feb 21 – Mar 18

Five digits. The calendar is computed on your device.

What each source says, applied to zone 8b

The same frost dates give different answers depending on whose rule you follow. These are all the published rules we hold for lettuce, worked out at zone 8b's median frost dates.

Table 1. Lettuce rules from every source, at zone 8b's median last frost (Mar 17) and first frost (Nov 13).
SourceWhatRuleZone 8b median
Colorado State3Used aboveSow outdoors2-4 weeks before last frostFeb 18 – Mar 3
Utah State4Sow outdoors2 weeks before last frostMar 3
Oregon State, central OR1Used aboveTransplant outdoors2 weeks before last frostMar 3
Oregon State, central OR1Used aboveStart indoors7 weeks before last frostJan 28
Texas A&M (E-502)5Sow outdoorsFrom 6 wk before to 2 wk after last frostFeb 4 – Mar 31
Texas A&M (E-502)5Plant for fall10-14 weeks before first frostAug 7 – Sep 4

Frost across zone 8b

  1. Last spring frostmedian Mar 17
  2. First fall frostmedian Nov 13
  • Frost-free season (median)
Figure 2. Frost dates across zone 8b, from 652 NOAA stations matched to 2,535 ZIP codes.

Planting lettuce with others

  • Cilantro Extension guidance Cilantro flowers attract aphid-eating beneficial insects (lacewings, lady beetles, parasitic wasps, spiders, syrphid flies) that reduce aphids on lettuce.6
  • Dill Extension guidance Dill flowers attract aphid-eating beneficial insects (lacewings, lady beetles, parasitic wasps, spiders, syrphid flies) that reduce aphids on lettuce.6
  • Fennel Extension guidance Fennel flowers attract aphid-eating beneficial insects (lacewings, lady beetles, parasitic wasps, spiders, syrphid flies) that reduce aphids on lettuce.6
  • Carrots Extension guidance Deep-taprooted carrots paired with shallow, wide-rooted lettuce use different soil layers, so their roots compete less.788

Sources

  1. Oregon State University Extension Service, When to start seeds indoors in central Oregon, reviewed 2024. Retrieved 2026-11-02.
  2. NOAA National Centers for Environmental Information, U.S. Climate Normals 2020: U.S. Annual/Seasonal Climate Normals (1991-2020), 2021. Retrieved 2026-11-02.
  3. Colorado State University Extension, Vegetable Planting Guide (CMG GardenNotes #720), reviewed September 2024. Retrieved 2026-11-02.
  4. Utah State University Extension, Suggested Vegetable Planting Dates for Utah, January 2018; revised May 2025. Retrieved 2026-11-02.
  5. Texas AgriLife Extension Service, The Texas A&M System, Texas Home Vegetable Gardening Guide (E-502), 2/09. Retrieved 2026-11-02.
  6. Penn State Extension, Herbs Make Good Plant Partners and Companions, Updated April 22, 2026. Retrieved 2026-11-02.
  7. Washington State University Extension, Gardening with Companion Plants (Home Garden Series), EM128E, December 2023. Retrieved 2026-11-02.
  8. University of California Agriculture and Natural Resources (UCCE Master Gardener Program), Companion Planting Chart: Companion planting in the vegetable garden, File dated 2023-09 in URL path; no date printed. Retrieved 2026-11-02.