Zone 1a planting calendar

What to plant in May: zone 1a

Zone 1a averages its last spring frost around June 20 and its first fall frost around August 10. Everything below is timed from those two dates, so it stays useful whether you're planting for summer or for a fall harvest.

These are zone-average dates. Check an area-level frost estimate from thirty years of nearby weather history and this calendar retimes itself.
Last frost: June 20
First frost: August 10
Winter lows: -60 to -55 °F
Zone 1a Almanac. What growers here actually recorded: sowing weeks, days to first pick, and yields.

Dormant care

  • Pre-sprout seed potatoesaround May 9

    Chit potatoes in a bright, cool spot for 2 weeks. Sprouted pieces jump ahead once planted.

Garden care

  • Wake the bedsaround May 16

    Turn in compost, cut down cover crops, and let the soil warm two weeks before the first sowing.

  • Harden off early transplantsaround May 23

    Two weeks of increasing outdoor time keeps cold-hardy seedlings from stalling when they go out.

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