Sweet corn is a warm-weather vegetable that requires specific temperature conditions for successful germination and growth. According to Utah State University, while germination begins at 55 degrees Fahrenheit, the optimum temperature range falls between 7 and 86 degrees Fahrenheit.
To maximize germination and prevent seed rot, soil temperatures should be at least 60 degrees Fahrenheit at the time of planting. If soil temperatures are below 75 degrees Fahrenheit, using seed pretreated with a fungicide is recommended to reduce losses from rot.
Proper seeding techniques and spacing can significantly impact yield and ear size. For standard planting, rows should be spaced 28 to 32 inches apart with seeds placed 7 to 8 inches apart within the rows at a depth of approximately 1 inch. This method produces roughly 24,000 plants per acre.
For those utilizing machine harvesting, a minimum spacing of 30 inches is recommended. Alternatively, spacing rows every 36 inches with seeds 7.5 to 8.5 inches apart can maximize ear size, resulting in a density of 20,000 to 23,000 plants per acre.
To maintain a steady supply of corn throughout the summer, successive plantings are suggested. Growers can predict maturity using several methods: following a calendar, observing when the first leaf unfurrows, using the days to maturity listed on seed packages, or calculating growing degree units (GDU).
Growing degree units, or cumulative heat units, offer an accurate way to predict crop maturity. The GDU formula is calculated as: [(Tmax + Tmin) / 2] – 50, where the base temperature for sweet corn is 50 degrees Fahrenheit.
When calculating, if the daily maximum exceeds 86 degrees Fahrenheit, 86 should be used in the formula. Similarly, if the daily minimum falls below 50 degrees Fahrenheit, 50 should be used. If the calculated GDU is less than the base temperature, there is no growth for that day.
For growers lacking local weather data, the Utah Climate Center’s database at climate.usu.edu or the Utah TRA
Ps website can provide necessary information.
Another strategy to extend the harvest period is planting multiple varieties with different ripening dates simultaneously. Examples include 'Early Sun Glow' which matures in about 63 days, 'Honey and Pearls' at approximately 76 days, and 'Serendipity' at roughly 82 days.
