Citrus and Freezing Weather


I am going to give you my suggestions on how to get your citrus through freezing weather.  To be on the safe side, you ought to keep your citrus above 26°F.  This is a conservative temperature and some citrus can survive much colder temperatures.  Tender new growth and fruit will freeze at slightly warmer temperatures.  Duration is also important because the plant or fruit has to have time to lose its heat before it is damaged.  Thick skinned fruit needs more time to lose its heat.  Of course, leaves and thin branches lose their heat the fastest so it will be damaged first. 

What happens is ice forms in the plant cells and ruptures the cells.  Now the state of the plant tissue will also determine its ability to withstand freezing temperatures.  If the water content is low in the plant cells and contains sugars or other dissolved plant chemicals, the temperature where ice crystals form will be lower (similar to the adding of salt to the ice water mixture to make old fashion ice cream).  Dissolved salts make the freezing temperature lower.  This is accomplished to a small degree by grafting varieties on to trifoliate rootstock which almost cuts off the water supply to the grafted scion.

My Fairchild mandarin Christmas day 2004.

Most Hardy to least Hardy:

An approximate list of the most hardy citrus trees to the most sensitive citrus trees:  t
rifoliata, trifoliata hybrids, kumquats, kumquat hybrids, meyer lemon, mandarins/tangerines, oranges, tangelos, pummelos, grapefruit, lemons, limes, citrons.

Suggestions for freeze protection for trees in the ground: