Start indoors or direct sow?

Direct sowing is preferred because corn establishes quickly and does not benefit much from transplanting. Transplants can be used for a small head start, but they must be very young and handled gently.

When to start Sweet Corn seeds

Direct sow 1 to 2 weeks after the last spring frost, once soil is at least about 60 F. If starting indoors, sow 2 to 3 weeks before the last frost in deep cells and transplant promptly after frost risk passes.

How to sow the seeds

Plant seeds 1 to 1 1/2 inches deep in fertile, well-drained soil. For indoor starts, use deep cells or pots with seed-starting mix, one seed per cell, to avoid root disturbance.

Germination

Corn commonly germinates in 7 to 10 days when soil is warm. Soil around 65 to 85 F and consistent moisture support even emergence.

Seedling care

Give indoor seedlings bright light and water when the mix begins to dry at the surface. Outdoors, thin plants to recommended spacing, keep the bed weed-free, and avoid soggy conditions that can cause seedling disease.

Transplanting & hardening off

Harden off seedlings for several days and transplant while they are small, after nights have become mild. Plant at the same depth, keep roots intact, and set plants in a block for pollination.

Tips

Choose a variety suited to your season length, especially in northern areas. Plant all corn in blocks of at least several short rows so pollen reaches the silks reliably.

General seed-starting guidance for US home gardens; timing depends on your local frost dates and variety. Page updated Aug 4, 2026.