Germination of Zea Maize Seeds

Outdoor Soil Temperatures

• Zea maize seeds germinate in soil between 50 and 100 degrees Fahrenheit. Insert a soil thermometer 4 inches into the soil in the planting bed. Take soil temperature readings in the morning. Sow Zea maize seeds when the temperature rises to 55 degrees Fahrenheit and the last frost date has passed. Seeds germinate reliably at this temperature, and early planting maximizes the length of the growing season. Hybrid varieties labeled "super sweet" require a soil temperature of at least 65 degrees Fahrenheit.

Starting Seeds Indoors

• When germinating Zea maize seeds indoors, aim for an optimum soil temperature of 80 degrees Fahrenheit for rapid, reliable seed germination. Use a pot or seed flat filled with soilless seed-starting mix. Keep the pot or flat in a greenhouse or indoors in a area with filtered sunlight. In cold areas, bring up the soil temperature and keep it consistent, using a heating pad. Home and garden stores sell heating pads specifically for germinating seeds and warming soil.

Germination and Growing Time

• Germination time varies, depending on soil temperature. In general, Zea maize seeds require five to 10 days to germinate and emerge from the soil. At the low end of the temperature range, germination takes closer to 10 days. At optimum temperatures, the seeds require only five days. When the soil reaches the upper temperature limit of 100 degrees Fahrenheit, germination is hindered due to excessive heat in the soil. Zea maize requires 60 to 90 days to grow from seed to harvestable size.

Planting Depth

• Planting depth depends on soil temperature. Plant Zea maize seeds in soil 50 to 75 degrees Fahrenheit a half-inch deep. In soil 75 degrees and higher, plant the seeds 1 1/2 inches deep, according to the University of Illinois Extension. Water the seeds right after planting, then daily or as often as needed to keep the soil consistently damp during germination and emergence. Space the seeds 9 to 12 inches apart.