How to Grow Sweet Corn
Zea mays
Sun-drenched summer ears, sweetest the moment they leave the stalk.
By the Plants by Zone Editorial Team · Reviewed June 1, 2026
About sweet corn
Sweet corn is a tall, hungry warm-season grass that rewards space and rich soil with ears of unbeatable just-picked sweetness. Because it is wind-pollinated, it must be grown in blocks rather than single long rows. It is a heavy feeder that grows fast once summer heat arrives.
When to plant and harvest sweet corn
Timing is relative to your frost dates. Find your USDA zone for exact dates, or browse the month-by-month calendars.
Start seeds indoors
Generally not recommended — corn dislikes root disturbance
Transplant outdoors
Only with care, in short-season zones
Direct sow
1–2 weeks after last frost, once soil is 60°F+
Harvest
Mid-to-late summer, ~20 days after silks appear
How to grow sweet corn step by step
- 1
Wait for soil to reach 60°F — corn rots in cold, wet ground.
- 2
Sow in blocks of at least four short rows, not one long row, so wind can pollinate every ear.
- 3
Thin to 8–12 in apart once seedlings are a few inches tall.
- 4
Side-dress with nitrogen when plants are knee-high and again when they tassel.
- 5
Water deeply and consistently during tasseling and ear fill — drought now means gappy ears.
- 6
Harvest when silks are brown and kernels spurt milky juice when pierced.
Common problems growing sweet corn
⚠ Gappy ears with missing kernels
Poor pollination — always plant in blocks, not single rows, and avoid isolating just a few plants.
⚠ Corn earworm in the tips
A few drops of mineral oil on the silks after pollination, or simply cut off the damaged tip at harvest.
⚠ Plants blown over (lodging)
Hill soil around the base; corn sets prop roots that anchor it in wind.
✗ Keep away from
🧺 Harvesting sweet corn
Pick in the cool of the morning when silks are dry and brown and the ears feel full to the tip. Sugar converts to starch within hours, so cook or chill it fast — flavor is never better than the minute it is picked.
Sweet Corn: frequently asked questions
Why is my corn not filling out?＋
Almost always incomplete pollination. Grow corn in a block of at least 4×4 plants so wind carries pollen to every silk.
How do I know when corn is ready?＋
About three weeks after silks appear, when they have turned brown and a punctured kernel releases milky (not clear or doughy) juice.
Grow sweet corn in your zone
See exactly when to plant and what else to grow alongside sweet corn, tailored to your USDA hardiness zone.
