Zone 4a planting calendar

What to plant in September: zone 4a

A rule-of-thumb starting point for zone 4a: last spring frost around May 20, first fall frost around September 20. Zones are set by winter lows, not frost dates, so two gardens in the same zone can be weeks apart. Measure your ZIP below for dates from your area's own 30-year record.

These are zone-average dates. Check an area-level frost estimate from thirty years of nearby weather history and this calendar retimes itself.
Typical last frost: May 20
Typical first frost: September 20
Winter lows: -30 to -25 °F
Zone 4a Almanac. What growers here actually recorded: sowing weeks, days to first pick, and yields.

Direct sow for fall

  • Radisharound Sep 1

    Counts back 30 days from your first frost. Frost-hardy: light freezes sweeten it.

Plant to overwinter

  • Garlicaround Sep 6

    Cloves go in about two weeks before first frost. They root now, sleep, then bulb next summer.

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