When temperatures at night drop well below zero and daytime highs only reach in the mid-teens, greenhouse growers who have started production are feeling frustrated.
This is young plant production time, when many growers receive unrooted cuttings, liners and plugs for spring production. Cuttings shippers are delaying deliveries because the tender cuttings cannot withstand the frigid temperatures. Some arrivals have been frozen to the point that one grower says, “When they’re that cold, they’re dead, and dead is dead, so don’t attempt to plant them out to see if they will root.”
When opening bags, smell the cuttings; if they have a compost-like smell, they probably are starting to decay from the cold temperature damage. Michigan State University Extension recommends growers who receive cold-damaged plant material contact the vendor right away and make a damage claim.
Sometimes you can immediately determine if the plant material is damaged; other times, you may want to leave the box inside over night at 55°F to 60°F and recheck the plants the next day and look for damage. If you decide to put them out on a bench to root, flag the group so if they do not grow as expected, you know it was because of the cold temperature damage during transit.
Click here to read the full MSU article on chilling injury on cuttings, including moderately and very cold sensitive species and more photos of symptoms.
This article was published by Michigan State University Extension. For more information, visit the Michigan State University Extension website.