Zone 3a planting calendar
What to plant in August — zone 3a
Zone 3a averages its last spring frost around May 30 and its first fall frost around September 10. Everything below is timed from those two dates, so it stays useful whether you're planting for summer or for a fall harvest.
Last frost: May 30
First frost: September 10
Winter lows: -40 to -35 °F
Garden care
- Scout for pests weeklyaround Aug 1
Squash bugs, hornworms and cucumber beetles peak now — five minutes of hand-picking beats a rescue spray.
Direct sow for fall
Sow cover crop
- Cover crop (cereal rye + crimson clover)around Aug 11
Sown a month before frost it germinates, holds your soil all winter, and feeds it in spring.
Plant to overwinter
- Garlicaround Aug 27
Cloves go in about two weeks before first frost — they root now, sleep, then bulb next summer.
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