Plants must be handled carefully during packaging and shipping to avoid mechanical damage. Wounded plants can produce significant levels of ethylene. Sleeving plants can also cause wounding. Make sure that the sleeving material has holes that allow the ethylene gas to diffuse away from the plant, otherwise the microclimate around the sleeved plant can quickly accumulate damaging levels of ethylene (Figure 1). Sleeve plants just before they are being shipped and remove the sleeves as soon as possible. Open carts are a great way to transport your finished crop because it is an efficient way to move plants without damage, and it allows for air flow around the plants within the truck (Figure 2). Use electric pull-carts to transport the plants from the production area to the loading dock. If you put shrink wrap around the carts to keep plants in place, this can also create a microclimate with high relative humidity and high ethylene levels. Minimize the time that plants are on these carts and make sure that the plants are held in place by the wrap, but not completely sealed in. Deadheading flowers and removing dying leaves makes the crop more attractive, but it also removes potential sources of ethylene. Dying flowers and leaves produce ethylene, and botrytis and other fungi that degrade dying plant material also produce their own ethylene.
Package and sort orders in a well ventilated loading dock area that is free of sources of ethylene. If possible, load trucks in the early morning hours when it is cooler. Plants not only produce more ethylene at higher temperatures, but they are more sensitive to ethylene damage at high temperatures. This means that lower amounts of ethylene are needed to cause damage at high temperatures. Do not let truck engines idle while loading and do not use propane or gas powered forklifts inside the trucks or enclosed areas where plants are being held. The combustion of propane, natural gas or gasoline can produce ethylene. Ethylene from external or non-plant sources can cause direct damage to plants, but it also causes the exposed plants to increase their own ethylene production.
Ethylene is such a problem during shipping, because it is a gas. If any plants in your shipment are producing ethylene it is released into the air and can move throughout the truck. If plants are sealed in a truck for 1 to 3 days (or more) levels of ethylene in the ppm range can accumulate and cause significant damage to the entire shipment.
Dr. Michelle L. Jones
D.C. Kiplinger Chair in Floriculture
The Ohio State University
Department of Horticulture and Crop Science