From the Grove: Freezing Fruit
Did you know that even the Sunshine State can experience a couple of days each year where the temperatures plummet below the freezing point of 32 degrees? Although these frosty days aren’t an annual guarantee, when they do occur, citrus farmers must be on high alert, ready to take proactive measures to shield their groves from the cold’s damaging effects. In our groves, Benny and Ben McLean, who are Uncle Matt’s father and brother, have devised a clever protocol to keep our citrus trees “warm.” This tried-and-true technique is a testament to the power of cooperation with Mother Nature. However, history reminds us that she hasn’t always been kind to citrus farmers.
Benny often reminisces about the pivotal moment that changed the citrus landscape in Central Florida. While Citrus Greening Disease is often blamed for the decline in the state’s overall orange production, the devastating blows began in the 80s when a series of freezing temperatures severely damaged all citrus groves. In 1983, 1985 and 1989, the heart of Florida saw temperatures as low as 17 degrees. Farmers judiciously prepared with their freeze procedures, but sustained winds during these frigid days and nights were ineffective.
Freezes are tricky as Florida’s winter months coincide with harvest season. Imagine this: icy temperatures strike, and the fruit is still on the trees. If the fruit isn’t harvested before the freeze, farmers risk losing not only their entire crop but also the trees themselves. On the other hand, if the citrus has already been picked, farmers can concentrate on protecting the tree’s interior from the cold, potentially saving it from irreparable damage.
If you drive by a grove and see a picture like the one above, you can rest assured someone didn’t forget to turn off the irrigation. What is this? Microjet irrigation! This involves running water that’s approximately 72 degrees and comes directly from the underground aquifer. As water makes contact with cold air, heat is released as it turns from liquid to solid. This isn’t a radiating heat you feel, but it’s warm enough to make an impact with the goal of preventing tree death. This “heat” is held in the tree’s canopy so that the warmer air is more focused on the trunk rather than the exterior branches. Microjet irrigation is usually successful as long as the irrigation remains running and the wind doesn’t blow the heat out from under the canopy. Benny advises that once you see the frozen base begin to drip around sunrise, it’s safe to turn off the running water.
How can we assess whether a grove endured the harsh freeze? According to Benny, it’s as straightforward as inspecting the leaves. If they drop to the ground, the tree is still living. This indicates that the fruit, if any remained unpicked, and the leaves were primarily impacted by the temperatures, not the tree’s wood. Conversely, if the leaves remain attached for several days, it signals that the tree perished due to being completely frozen.
At-Home Freeze Protection:
Most backyard citrus tree owners don’t possess a microjet irrigation system setup to run directly below your backyard orange or lemon tree, but that doesn’t mean all is lost if extremely cold weather is in the forecast. Try using Benny’s backyard tree trick: Purchase extra-large trash bags to use as a blanket. (Pro tip: Some hardware stores will sell up to 96-gallon sized bags.) Cover your tree with the bag so that it can be tied at the base of the trunk. Before you seal the bag, place a 100-watt lightbulb inside the bag at the base of the tree. The trash bag will insulate the tree and the light warms from the inside to keep your tree warm.
Fortunately, Florida’s cold snaps are relatively short lived. With proper precautions in place and the help of a light breeze, it is possible to keep both large groves and backyard citrus trees thriving through winter. Reach out to us if you need additional cold weather tips!
