Protecting your citrus trees from frost is one of the most important things you can do to ensure a successful harvest at the end of the growing season. Frost implies that a tree has been, or will be, exposed to temperatures 29 degrees F or lower for 30 minutes or longer.
1. Protective Planting
The simplest ways to protect citrus trees from frost is to plant them in an area less susceptible to cold temperatures. To do this, consider planting them in a group with other trees or close to a wall on the south-facing side of your yard or garden, so they can absorb and retain more heat. Another precaution is to plant them uphill, as colder winds tend to make their way down the slope.
2. Defensive Measures
If your citrus trees are already planted and you are looking to take measures to improve their resilience to frost, remember to always keep the soil wet, as wet soil retains heat better than dry soil. But sometimes, the weather forecast will take you by surprise and may bring an unexpected cold front that could damage your citrus trees.
3. Protective Frames and Insulating Covers
To combat unexpected cold weather, build a frame or box over your trees using PVC piping or 2x4’s and then secure plastic around the frame all the way down to the ground. This allows the heat stored in the ground to escape into the tented box while keeping the cold air away from the trees. The frame acts as a support in case the plastic cover is too heavy for the branches to support. If you do not have time to build a frame, tent your citrus trees in plastic, or even a bed sheet, to try and minimize the damage.
4. Holiday Lights and Blankets
When in doubt about what is best to do, give your trees the same treatment you would want — wrap them in something that will retain their heat and provide them with an outside heat source if necessary. In cases of extreme cold, you can wrap holiday lights around the interior of the tree, which will effectively radiate enough heat around the tree to minimize the frost damage.
5. Frost Recovery
If all else fails, and your citrus plants end up retaining damage from frost, do not prune them in the early spring. Wait until later in the season when new shoots begin to sprout, at which time you can fully assess the damage and trim away any dead twigs or stems without damaging the new growth.