Growing-degree Day - Baselines

Baselines

10 °C is the most common base for GDD calculations, however, the optimal base is often determined experimentally based on the lifecycle of the plant or insect in question.

• 5.5 °C wheat, barley, rye, oats, flaxseed, lettuce, asparagus
• 6 °C Stalk Borer
• 7 °C Corn rootworm
• 8 °C sunflower, potato
• 9 °C Alfalfa weevil
• 10 °C maize (including sweet corn), sorghum, rice, soybeans, tomato, Black cutworm, European Corn Borer, Coffee (Jaramillo-Robledo & Guzman-Martinez published by Cenicafé), standard baseline for insect and mite pests of woody plants
• 11 °C Green Cloverworm
• 12 °C many other crop calculations
• 30 °C the USDA measure heat zones in GDD above 30 °C; for many plants this is significant for seed maturation, e.g. reed (Phragmites) requires at least some days reaching this temperature to mature viable seeds

GDDs may be calculated using either Celsius or Fahrenheit, though they must be converted appropriately; 5 GDDC = 9 GDDF