Sweet corn seeds should be planted outdoors approximately two weeks after the last frost of the spring season. Successful germination of sweet corn seeds requires a soil temperature above 60 degrees Fahrenheit, while the super-sweet corn variety thrives better above 65 F.
If the spring season is unusually cold, the ground can be warmed for corn seeds with a black plastic ground cover. Sweet corn seeds should be planted 1 inch deep in well-drained soil, spaced roughly 4 to 6 inches apart. Once the plants are about 4 inches tall, they should be thinned out until there is a spacing of 8 to 12 inches between plants.