Zone 3b planting calendar

What to plant in August: zone 3b

A rule-of-thumb starting point for zone 3b: last spring frost around May 25, first fall frost around September 15. 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 25
Typical first frost: September 15
Winter lows: -35 to -30 °F
Zone 3b Almanac. What growers here actually recorded: sowing weeks, days to first pick, and yields.

Direct sow for fall

  • Cilantroaround Aug 1

    Counts back 45 days from your first frost. Takes a light frost with cover.

  • Radish2 sowings: Aug 13 and Aug 27

    Succession sowing 2 of 3. Sow every 14 days for a steady cut. Sowing again a few weeks later keeps the harvest coming instead of arriving all at once.

  • Spinacharound Aug 17

    Counts back 40 days from your first frost. Frost-hardy: light freezes sweeten it.

Transplant for fall

  • Kalearound Aug 2

    Last safe transplant date to mature (55 days) before frost on 09-15.

Sow cover crop

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