A dwarf fruit tree can provide a small family with all the fruit they can eat when it is in season. Many of the stone fruits, such as plums, apricots and peaches, require a certain amount of winter cold in order to generate the springtime blossoms that result in summer fruit. But others, such as many varieties of citrus, can be badly damaged, or their developing fruit can be badly damaged, by frost that occurs in late winter or early spring. One of the advantages of dwarf fruit trees is that you can grow them in large pots, which you can move under cover or indoors when needed to protect the tree from cold.
Plant your dwarf fruit tree in a large pot when you first purchase it. This allows you to give the tree the good drainage it needs in addition to enabling you to move it to a protected area, even into your garage temporarily, when the weather is forecast to drop below 32 degrees Fahrenheit.
Drape Christmas lights around your tree if it is growing in the ground or you cannot lift a larger tree in a large pot. Turn them on when the sun sets and leave them on all night.
Fill plastic milk or water jugs with water and then set them around the base of your tree. The water will heat up a bit during the day and at night the warmth that the water generates will serve as a type of passive solar energy.
Build a movable frost frame with 2 by 2 boards in either an A-frame or square shape. Set it over your tree and then cover it with clear plastic, blankets or tarp. If you use blankets or tarp, remove them during the daytime. You can leave clear plastic over your tree all winter.
Set up a hose with a wide-spraying sprinkler attached to it near your tree. When the temperature drops into the 30s on nights it is forecast to drop even farther, turn on the sprinkler and let it run all night. Moving water cannot freeze and it will protect your tree.