The New Almanac

USDA Zone 11b

Zone 11 · The Frost-Free Line

Average annual extreme minimum temperature: 45 to 50 °F (7.2°C to 10°C).

Southernmost Florida, Hawaiian lowlands, Puerto Rico's cooler heights — 40 to 50°F winters where frost is a rumor. Heat, wind, and ceaseless pests replace cold as the forces a gardener plans around.

By the numbers

Median season
Year-round
ZIPs tracked
13

Medians across every ZIP we track in zone 11b, derived from NOAA 1991–2020 climate normals. Look up your own ZIP for local dates — within a zone, frost varies by weeks.

Where you'll find zone 11

The southernmost mainland: Miami-Dade and the warmer pockets of South Florida reach 11a, along with Hawai'i's mid-elevation lowlands and the higher country of Puerto Rico. In our ZIP data, zone 11 marks the line where frost dates disappear entirely.

Vegetables that earn their keep

  • Year-round production — CTAHR: no state is "climatically better situated... for production of a year-round vegetable supply" than Hawai'i
  • Cool-season crops (broccoli, cabbage) in the winter months at low elevation — or year-round at altitude (CTAHR)
  • Warm-season crops (okra, New Zealand spinach) own the warm lowland months (CTAHR)
  • South Florida's reversed calendar applies: winter is prime, summer is managed around heat and rain (UF)

Fruits & perennials that overwinter

  • Mango and avocado, fully at home (UF cold tolerances are academic here)
  • Papaya — production wants minimum temperatures above 60°F; cooler nights deform fruit ("carpeloidy"), and 90–95°F heat can cause female sterility (CTAHR)
  • Banana — given abundant moisture and drainage (CTAHR)
  • Citrus everywhere; temperate chill-requiring fruit is effectively off the menu

Frost stops being the question

Zone 11 is the first band where the winter-cold number that defines USDA zones stops mattering for annual vegetables. What replaces it: heat windows, rain seasons, and elevation. CTAHR's Hawai'i guidance grows cool-season crops in lowland winters but year-round at higher elevations — altitude does the work latitude can't.

The 65–78°F engine

CTAHR notes Hawaiian summer crops grow at 65–78°F day after day — the fast, even growth that produces multiple plantings per year. The flip side is that nothing else pauses either: "wherever gardens are grown, there are insect and disease enemies that must be fought continuously." No winter ever resets the board.

Papaya's narrow comfort band

Papaya is the zone's indicator species: it wants nights above 60°F (below that, fruit deforms with carpeloidy) but suffers female sterility in 90–95°F heat (CTAHR). One crop, both ceilings — a preview of how tropical gardening trades frost risk for heat-and-humidity management.

Wind and salt

CTAHR's papaya guidance doubles as coastal-tropics advice generally: constant wind deforms growth and ~40 mph gusts can uproot trees in loose soils, so windbreaks go in before the orchard; salt spray desiccates foliage near the shore. Hurricanes carry both hazards to an extreme (UF's wind- and salt-management guidance applies in full).

Plant guides, timed to your frost dates

Every guide gives its planting calendar relative to your last frost — the dates above (or your ZIP's) drop straight in.

Sources