General Standards for Primary Shipment

For unfrozen stock, an environment of 33 to 34 °F and 95 percent or higher relative humidity in the seedling packages, with adequate air circulation, will be maintained during shipping. Incompletely cooled stock (recently lifted) may be transported if the cool-down process can be continued without interruption while the stock is in transit. For frozen stock, temperatures should be maintained at 28 to 32 °F. Protect seedling containers in transit from any conditions contrary to the above standards.

This topic is covered more thoroughly in District Receipt of Tree Seedlings.