Just hang a light bulb in the center of tree and cover it with a tarp. This method will prevent flower killed from late frost and you will have a fruitful season.

Tony

Well, too many trees too far away

Someone should design and market some sort of foldable panel greenhouse that automatically covers up the plant when the temperature drops too low.

I think you'd certainly need a pile of hand warmers, and also a way to trap the heat to make a substantial difference. I assume you don't have blossoms yet, with temps that low expected… so I'm guessing you're trying to protect the unopened buds that are starting to swell?

After years of wrestling with various frost protection measures (in windy spring weather) with very little success, I've found crossing the fingers to be the best method! That, and avoiding plants that come out of dormancy too early…

very warm here this winter. my apricot is blooming already. rest of the trees are about to.I am in Denver area.