Corn Seed Starting Tips

Corn seedlings

Corn is a tender, warm-weather crop. Sweet corn is commonly grown in gardens.

Sow corn in the garden 1 week after the last frost when the soil temperature has warmed to at least 65°F (18°C). Start corn indoors 4 weeks before transplanting to the garden. Seedlings as small as 1 inch (2.5 cm) can withstand transplanting.

Succession plant corn 1 to 2 weeks apart to extend the harvest. Time the last sowing so that harvest comes a week or two before the first expected frost in fall.

Planting corn in cold soil or chilly weather risks poor stands and poor yield.

Corn matures 60 to 100 frost-free days after sowing.

Sowing and Planting Tips:

  • Grow corn from seeds or seedlings.
  • Seed is viable for 2 years.
  • Direct sow corn in the garden in spring after all danger of frost has passed and the soil has warmed to 60°F (16°C).
  • Optimal soil temperature for growing corn is 65°F to 75°F (18-24°C). Corn will not germinate in soil chillier than 50°F (10°C).
  • To start plants indoors, sow seed in peat pots 4 to 3 weeks before planting out. The optimal indoor temperature should be 70°F (21°C) until germination.
  • Sow seed 1 inch (2.5 cm) deep.
  • Seeds germinate in 4 to 10 days.
  • Transplant corn into the garden after the soil has warmed to at least 70°F (21°C).
  • Space corn 12 inches (30 cm) apart in all directions; plant corn in blocks of at least 4 rows for optimal pollination. About 4 plants for each square foot.
  • Keep the soil just moist; letting the soil dry out will interrupt pod development.
  • Fertilize with fish emulsion or a soluble complete fertilizer at half strength.
  • Add aged compost to planting beds in advance of transplanting.
  • Corn prefers a soil pH range of 6.0 to 7.0.
  • Grow corn in full sun for best yield.
  • Common corn pest enemies include aphids, armyworms, corn earworms, corn maggots, corn rootworms, cucumber beetles, flea beetles, Japanese beetles, leafhoppers, seed corn maggots, birds, and raccoons.
  • Common diseases include bacterial blight, mosaic virus, rust, corn smut, southern corn leaf blight, and Stewart’s wilt.

Interplanting: Plant corn with bush beans, beets, cabbage, cantaloupe, cucumbers, melon, potatoes, pumpkins, and squash.

Container Growing: Corn may not be a good choice for containers unless you have large containers that can hold multiple plants (to insure pollination). Choose a container 21 inches (53 cm) wide and 8 inches (20 cm) deep; plant at least 3 plants per container.

Recommended Planting Calendar:

  • 4-3 weeks before transplanting seedlings to the garden: start seed indoors.
  • 1 week before the last frost in spring: direct sow seed in the garden; protect seedlings from chill with a row cover.
  • 2-3 weeks after the last frost in spring: sow succession crops.

Recommended Varieties: Early planting sweet corn varieties include ‘Early Sunglow’ and ‘Polar Vee’; midseason varieties include ‘Golden Bantam’ and ‘Honey and Cream’; late-season varieties include ‘Country Gentleman’ and ‘Silver Queen’. For small gardens try ‘Golden Midget’ and ‘Tom Thumb’.

Botanical Name: Zea mays var. rugosa

Corn is a member of the Poaceae or grass family.