Temperature and Humidity Control

The effects of cold storage on field performance of seedlings depend on nursery practices, root growth potential at lifting time, and length of storage (assuming seedlings are properly packaged and temperature and humidity are kept within carefully controlled limits). Temperatures should not be allowed to fluctuate. Storage facilities must have the insulation, cooling capacity, and air circulation needed to maintain a constant 33 to 34 °F temperature and 95+ percent relative humidity within the seedling package for unfrozen stock and a temperature of 26 to 28 °F for frozen stock. Seedlings must be kept within carefully controlled temperature and moisture limits between lifting and planting. Exposure to extreme temperature or moisture conditions reduces seedling survival.

Monitoring must be sufficient to ensure these environmental conditions do not change. It is essential that the temperature/humidity environment be constantly maintained throughout the seedling storage period, including nursery storage, transportation, and field storage.