Zone 4a planting calendar

What to plant in August: 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

  • Spinach2 sowings: Aug 1 and Aug 22

    Succession sowing 2 of 3. Sow every 21 days for a steady cut. Sowing again a few weeks later keeps the harvest coming instead of arriving all at once.

  • Lettucearound Aug 1

    Counts back 50 days from your first frost. Takes a light frost with cover.

  • Radish2 sowings: Aug 4 and Aug 18

    Succession sowing 3 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.

  • Cilantroaround Aug 6

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

Transplant for fall

  • Kalearound Aug 7

    Last safe transplant date to mature (55 days) before frost on 09-20.

Sow cover crop

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