Sounds like the coldest temps in quite a few years are coming later this week...
Based on classes I have taken in Immokalee --with growers--, here is my best plant advice:
Water. Water. Water. Soil should be moist prior to the night of frost so that the water in the soil can warm up during the day and HOLD HEAT throughout the night. It is a hot water bottle for plants.
DO NOT throw plastic over plants. Plastic touching plants does not protect them. I shudder when I see Walmart bags over a branch of a shrub. Believe it or not, the plant is better off without it.
Tuck plants in. Edges of the covering cloth needs to --seal-- to the ground and preferably NOT TOUCH THE PLANT unless you have purchased special frost protection covers. Think of yourself outside during a temperature drop with only a moist sheet for cover over your shoulders. Soil is the warmest place when temperatures drop. Goal is to allow the soil's warmth to fill up and heat inside cover like a hot air balloon.
Remove covers during the day. If temps warm up past freezing that is. Covers prevent the plant from fully photosynthesizing (form of eating) and evaporating moisture from the leaves during the day.
Old fashioned "Edison" bulbs. If you got them, string them on your most sensitive trees. Incandescent bulbs generate HEAT. Hard to find nowadays.
Move potted plants. Move them to the garage, against the house, or under a tree (yes this works to some degree because the tree "holds" heat under the canopy).
DO NOT run the sprinklers the night of the "event". Yeah. I thought this was the answer but unless you want snow or ice in your yard, this is not the answer. Warm water from the ground, right? When it is that cold, it turns to snow or ice. Let's not go there. We all read/heard of this via the news when citrus growers desperately trying to save their trees. Vegetables are not citrus and unless you have overhead (8') sprinklers for each of your cold sensitive trees, again, let's not go there.
I have tested other things and, to-date, this is the best information I have on dealing with freezing in a sub-tropical area.
