Growing fennel in zone 5b
(Zone 5b = an average winter low of -15°F to -10°F.)
In USDA zone 5b, the typical last spring frost is May 1 and the first fall frost is October 10. Here is when to plant fennel against those dates.
Typical timing
Zone 5b planting schedule
Evidence trail
How these dates are built
Sprout applies the cited planting offsets to the typical zone 5b 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 Fennel in Your GardenUtah State University Extension. Supports indoor seed-starting timing (direct), direct-sowing timing (normalized), and days to maturity (direct).
Method note
Annual lifecycle (Florence fennel, a cool season annual), full-sun requirement, indoor start 4-6 weeks before the frost-free date, preferred direct seeding around the frost-free date, 60-90 day maturity, 8-12 inch in-row spacing with rows 18 inches apart, 1/4 inch seed depth, pH 6.5-8, and the bolting / aphid / thrips / stalk-splitting problems from this page. waterInchesPerWeek set to the 2 inch upper end of the stated 1-2 inch range. Indoor and direct-sow windows are anchored at the last spring frost (week 0).
These are zone 5b averages
Computed from 2,843 ZIP codes in zone 5b. 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.