Our friends in horticulture typically discuss the topic of food trees, but many of Louisiana’s forest landowners experienced damage to the fruit and nut trees in their home landscapes following the “big freeze” of February 2021. Many have asked for more information about how cold temperatures affect food trees and how they can limit damage to their fruit and nut trees in the future.

Beginning with citrus, choosing a cold hardy variety based on the conditions where you live can help you avoid freeze damage that occurs when temperatures stay below freezing for more than a couple days. Here is a list of citrus fruits and their respective cold tolerance

• Kumquat (can tolerate temperatures under 20 degrees Fahrenheit).
• Satsuma (can tolerate temperatures in the low 20s degrees Fahrenheit).
• Oranges, grapefruit, lemon (have a cold tolerance between 22–27 degrees Fahrenheit).
• Lime (can tolerate temperatures down to 29 degrees Fahrenheit).

When planting citrus, Ben Salley of the Simply Citrus Nursery in Columbia, South Carolina, recommends siting citrus trees on the south side of a wall or a dense tree so they get plenty of sunshine and are protected from north breezes. In addition, research conducted by the LSU AgCenter suggests that citrus trees growing on bare ground have a higher probability of survival than citrus trees growing in turf areas because heat from the ground can radiate upward into the canopy.

Freezing Temperatures at LSU AgCenter Research Stations, 2/21

Bobby Fletcher, a former horticulturist with the AgCenter, shared these methods for protecting citrus when the temperature will be below 27 degrees Fahrenheit for an extended period:

• Entirely cover the plant with a frost cloth, sheet or blanket; make sure the cover does not touch the foliage.
• Extend the cover all the way to the ground.
• Remove the cover the next morning when the temperatures begin to rise.

You can also install small lights (e.g., Christmas lights) on the trees to increase the temperature around branches and foliage. Use traditional lights, not LED.

If you suspect your citrus trees have sustained injuries due to a freeze, wait to prune them until mid-spring when you can assess the full extent of the damage. Pruning the trees too early can be counterproductive because it may stimulate bud activity before the cold weather and threat of additional freezing temperatures has passed.

The LSU AgCenter has a free downloadable guide to home citrus production in Louisiana that you can find by searching for publication ID: 1234 at lsuagcenter.com. The AgCenter also offers a free online course with information about freeze damage symptoms and recovery at https://www.lsuagcenter.com/topics/lawn_garden/master%20gardener/the-backyard-orchard-school/home-citrus.

Figs are also susceptible to freeze damage in Louisiana. Like citrus, some varieties are more cold hardy than others. This list ranks some fig varieties on a scale from 1 to 5, with 1 being most susceptible to freezing temperatures and 5 being least susceptible to freezing temperatures:

The steps to protect citrus are also applicable to figs. In addition, a gardener who grew up in Louisiana enjoying fresh figs and later moved to Missouri shared with us that he keeps his fig trees in large containers on plant caddies, then moves his trees into his garage during the winter months.

The LSU AgCenter also has a free downloadable guide to commercial and home fig production in Louisiana you can find by searching for publication ID: 1529 on http://lsuagcenter.com.

If you’ve successfully nurtured your citrus and fig trees during heavy freezes, you may want to try your hand at growing macadamia nut trees. Macadamia trees are native to Australia and named after John Macadam, a noted scientist and secretary of the Philosophical Institute of Australia in 1857. These evergreens are relatively hardy and tolerate mild freezing (28–32 degrees Fahrenheit), but like citrus and figs in Louisiana, may require some protection during the winter. You can find more information by searching for the blog post titled “Macadamia as an Alternative Crop in Florida” by Karen Stauderman, a horticulture agent with the University of Florida, which outlines some biology and history of macadamia in the U.S.

You can also receive more information by emailing LSU AgCenter forestry extension agent Keith Hawkins at khawkins@agcenter.lsu.edu.