Ultra-dwarf fruit trees are miniature versions of normal standard-size fruit trees but they produce full-size fruit. They are ideal to plant in the home garden because they are easier to prune, spray for pests and diseases, and harvest. Ultra-dwarf fruit trees are often planted in containers. Container-grown ultra-dwarf fruit trees allow the home gardener to take advantage of sunny areas, such as patios or driveways, where trees cannot be planted in the ground but potted plants can be situated. Growing fruit trees in containers also enables tender varieties to be grown in areas with severe winters where they would not survive if planted in the ground, as long as the pots are moved to a sheltered location during winter.
Creating dwarf fruit trees has its roots in ancient Greece, as far back as the 3rd century B.C. The practice reached a refined art in northern Europe by the 16th century and by the 19th century, both amateur and commercial growers throughout Europe were interested in creating dwarf fruit trees. Since the middle of the 20th century, commercial fruit growers in Europe have planted orchards featuring dwarf and ultra-dwarf fruit trees.
Genetic Versus Grafted
Genetic ultra-dwarf fruit trees are cultivars that have been selectively bred to grow no more than 6 feet high. They are able to grow on their own roots but are often grafted onto standard ultra-dwarfing rootstock to increase their resistance to pests and diseases. Grafted ultra-dwarf fruit trees are made by grafting a standard size variety of fruit tree to a rootstock that causes it to "dwarf" or to grow smaller than it would if it were grown on its own roots. Ultra-dwarf rootstock produces fruit trees which grow from 3 to 6 feet high.
The most prevalent type of fruit available as a grafted ultra-dwarf tree is apples. Peaches and nectarines also are available as grafted ultra-dwarfs. Selected cultivars of these types of fruit trees have been bred to grow less than 6 feet high on their own roots, without the use of dwarfing rootstock. These so-called "genetic" dwarfs are ideal choices to grow in containers.
Ultra-dwarf fruit trees require the same cultivation methods as their larger, standard-size relatives. The only difference is that ultra-dwarf and dwarf fruit trees can be cared for entirely from the ground; no ladder or other vertical lifting apparatus is necessary. Dwarfs can also be planted closer together than standard-size fruit trees, increasing the number of trees that can be planted per acre from 200 to 1,300. Even though each ultra-dwarf bears a smaller crop than a standard-size tree, the increased number of trees planted in the same amount of space produces a dramatic increase in fruit yields.
Ultra-dwarf and dwarf fruit trees bear full-size fruit, just like their standard-size relatives. The quality of fruit from these smaller trees is in many cases far superior to that from standard-size fruit trees. This is due in part to their smaller canopy of leaves, which allows sunlight to reach all of the fruits, which in turn allows each fruit to develop to its full potential. The short stature of these trees also makes it possible to effectively reach all of the developing fruit when practicing pest management, either organically or with chemical sprays.