In colder parts of the state, the most common limiting factor in home fruit production is cold damage to developing flower buds resulting from spring frosts. Selecting the proper site and variety is the first line of defense against spring frost damage.
When cold temperatures come during critical stages of bud development, raising the temperature around the bud only a few degrees can be the difference between having fruit and just having a shade tree. Dwarf or young trees can be protected by tarping the tree. Cover the tree with a canvas or poly tarp and tie or anchor the edges to prevent the tarp from blowing away. Flowers and buds that are in contact with the tarp will still be damaged, but the tarp will hold warmer air in the tree and keep the remaining buds warmer. To provide additional heat, a 60-watt light bulb may be suspended in the canopy center and left on through the night. Other simple heat sources include a small propane burner or burning charcoal briquettes. Remember, however, that the tree doesn’t need to be warm, just kept above the critical bud temperature for the particular stage of development. Promptly remove the tarp in the morning once the air temperature exceeds 32 F. Remember that too much heat will speed bud development, creating more challenges on the next cold night.