Chilly Greens; How Freezing Temps Affect Plants

February 3, 2011 | By webadmin

When the temperature level drops below freezing, different plants are damaged differently. Tender plants such as tropicals need to be protected. Even with protection, tender plants may not survive extended periods below 25 degrees.  Shrubs and trees benefit most from watering right before a freeze to help prevent dehydration.

With the type of freeze we are experiencing now (where temperature levels dropped below freezing for several days without thaw) damage can be done to plant tissue. Tissues freeze and the ice crystals slowly grow, just as the ice thickens on a lake.  Eventually the cells will burst and die.

Damage often appears as dried out or mushy leaves.  Sometimes the damage is done inside the plant, in the buds or in the cambial layer.  The cambial is layer of cells between bark and wood and is vital to woody plants.  The damage does not become evident for a few weeks, when anticipated growth does not happen.  

Depending on the amount of damage it may not show up until summer heat adds a second stress to the plants.  The best thing to do right now is wait and see what happens. It is not unusual for some shrubs to sprout low down on the main stems and above that would be dead that should be removed.  Grasses, roses and evergreens can be cut in about two weeks to ready them for spring, however do not cut away what you think is dead on woody shrubs until you can see where the new growth is coming from.  If you have a question contact your landscape or nursery professional.