When Should You Plant Sweet Corn?
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GardenSays
Sow sweet corn outside May 12 – May 19 — after frost danger passes and soil has warmed to ~65°F.
- Sow from
- May 12 – May 19
- Last sowing
- Jun 17
- Last frost (typ.)
- May 5
Sweet corn are frost-tender and germinate poorly in cold, wet ground — unlike peas or lettuce, you wait until AFTER the last frost (May 5) and until the soil warms. Sowing too early into cold spring soil rots the seed. The safe window in Minneapolis, MN opens around May 12.
- Plant sweet corn in a block of at least 3-4 short rows, not one long row — sweet corn is wind-pollinated and a single row pollinates poorly (gappy ears).
Do this this week
- 1.Too late to sow sweet corn this year — the last sowing that could mature before frost was ~Jun 17
- 2.Plan next spring: sow from May 12 once soil is warm
Calculated result · 3 verified sources · Checked 2026-07-17 · How we decide
Why
Your season fits sweet corn comfortably — first sowings mature well before the typical first frost (Oct 5), and later sowings extend the harvest.
Plant in a block of several short rows rather than one long row so wind can pollinate every ear.
- Warm-season crops need warm soil to germinate: cold, wet spring ground causes seed rot and poor stands, which is why they go in after frost, not before.
- Days-to-maturity versus your frost-free season sets how late you can keep sowing.
When this doesn't apply
- Sweet corn is wind-pollinated — a single long row pollinates poorly. Keep different types (especially super-sweet) separated or timed apart to avoid starchy cross-pollination.
- A cold snap after sowing can still kill seedlings — hold off if a late frost is forecast, even inside the window.
How this was calculated
- 1. Last spring frostMay 5Source guidance
Minneapolis, MN: typical (50% probability) last 32°F frost
- 2. First sowing windowMay 12 – May 19Calculated result
Sweet Corn is frost-tender — sow only after frost danger passes AND soil has warmed to ~65°F (7-14 days after the last frost)
- 3. Last safe sowingJun 17Calculated result
63-100 days to maturity must finish ~10 days before the typical first fall frost (Oct 5)
Data sources
- University of Maryland Extension — Growing Sweet Corn in a Home Garden — Sow sweet corn after danger of frost is past; super-sweet varieties need soil 65F. Plant in blocks of at least 3-4 short rows (not 1-2 long rows) for good wind pollination. Spacing 9-12 in in-row x 24-36 in rows. 63-100 days to maturity. Harvest when husks green, silks brown/dry, kernels full size at the milky stage. Keep uniformly moist, especially at flowering and ear development. (checked 2026-07-17)
- NOAA NCEI — 1991-2020 U.S. Climate Normals (freeze date probabilities) (checked 2026-07-15)
- National Gardening Association — frost date lookup (checked 2026-07-15)
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