One method is to install a large net above the trees to give them some extra shelter. Another one is cutting the grass short, West-Flemish fruit grower Els Lambrecht explained the VRT: "The soil is still giving off warmth after last week's hot spell. If you cut the grass short, you allow this warmth to escape. This can make a difference of 0.5 degrees Celsius."
Another way is to sprinkle the blossoms slightly: it will allow the formation of a tiny ice cap on the flowers, which will then serve as a kind of insulation. Other well-known methods are the installation of fire pits, though these are less effective than one would think.
Pear trees are the first ones to blossom, ahead of the apple and cherry trees.