Well winter has spring upon Florida rather quickly this year, bringing freezing temperatures that many of my palms trees cannot handle. Fortunately most of these are in pots, so the easiest fix to prevent them from freezing is bring them into to garage. This not only protects them from the frost but protects them from damaging winds as well, since the radiant heat from the house as well as the lighting in the garage will keep them happy.
Now I’m sure many of you however have planted a palm tree or two that are not as cold hardy, and therefore do not have the luxury of just bringing them in to protect them from freezing. If you are one of these people, here is what I suggest. First, you will need some way to provide heat to your protect your palm. Many people will first string a few strands of Christmas lights both around the trunk of the palm and over or through the fronds. Some even place a floodlight or two and angle them up towards the fronds. After placing your lights the next step would be to drape the palm with some sheets or a light blanket, carefully tying them down or if they are long enough weighting them down with a few rocks or bricks. Using these tips should help keep the ambient air around your palm above freezing, and thus prevent it from both frost damage and freezing.
A word of caution, whatever you do, do not use plastic sheeting on your palm, as this can actually trap moisture underneath which may freeze. Some people also use frost cloth, and it should be applied in the same fashion as stated above. However, in my opinion the added expense is not necessary.
If you are trying to protect a palm from a hard freeze, ultimately what you are then trying to is protect the trunk and heart of the palm, which rests at the top of the trunk where the fronds emerge. On top of the above recommendations, I would also wrap the entire trunk with a heavy blanket. Other suggestions are to surround the trunk with a cardboard box, then filling it with mulch all the way to the top, ensuring that you cover the heart area with a thick layer as well.
By no means will this necessarily ensure the survival of your palm from freezing temps, especially if you have a palm that is rated for Zone 10 planted in Zone 7, but it will certainly be better than leaving it unprotected. The final suggestion to protect your palm tree from freezing would be to only plant palms that can take sub freezing weather, such as a Butia, Phoenix, Washington or some other cold hardy palm tree.