Growing lettuce in zone 4b
(Zone 4b = an average winter low of -25°F to -20°F.)
In USDA zone 4b, the typical last spring frost is May 8 and the first fall frost is October 1. Here is when to plant lettuce against those dates.
Typical timing
Zone 4b planting schedule
Evidence trail
How these dates are built
Sprout applies the cited planting offsets to the typical zone 4b frost anchors. The result is a planning baseline for the zone, not a local weather forecast.
- USDA Plant Hardiness Zone Map, 2023USDA Agricultural Research Service / Oregon State University PRISM Group. Supports the USDA hardiness-zone band.
- U.S. Climate Normals 1991-2020NOAA National Centers for Environmental Information. Supports the median spring and fall freeze dates.
- How to Grow Lettuce in Your GardenUtah State University Extension. Supports indoor seed-starting timing (derived), outdoor transplant timing (normalized), direct-sowing timing (direct), and fall direct-sowing timing (derived).
Method note
All fields. Transplants near the last frost-free date, seed 2-3 weeks earlier, 5-6 weeks to grow transplants (sow-indoors re-expressed against last frost), spacing 8-12 inches in rows 12-18 inches (lower bounds stored), depth 1/4 to 1/2 inch (lower bound stored), water 1-2 inches/week (lower bound stored), aphids/slugs/flea beetles, tipburn and heat bitterness. Fall window converted from 'plant 50-75 days before maturity, maturity 1-2 weeks before first fall frost' at 7 days/week.
These are zone 4b averages
Computed from 1,251 ZIP codes in zone 4b. Your town's frost dates vary; enter your ZIP for dates built on your nearest weather station.
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Put these dates to work
The plant profile covers spacing, light, water, soil, and source-backed timing details. The growing guide covers preparation, care, and harvest technique.