Size Does Matter

Trees are easier to harvest and maintain when all the branches are within arm’s reach. Unfortunately, many fruit trees can grow up to 40 feet tall or even higher when left to their own devices. To keep them in bounds and to produce more high quality fruit, most fruit varieties are grafted onto roots of smaller-growing varieties. Tree nurseries slip a bud, called a scion, from a desirable fruit variety, such as ‘Delicious’ apple or ‘Bing’ cherry, under the bark of a dwarfing rootstock variety in early spring. Plant breeders and tree nurseries graft fruit trees for a variety to

• Reproduce exact copies of desirable trees.
• Reduce the mature size of the tree.
• Encourage fruit bearing at an earlier age.
• Increase disease and pest resistance.
• Adapt to different soils.
• Determine hardiness to particular climates.

Roots are one of the most cold-sensitive parts of a tree. Some rootstocks increase the trees’ hardiness to cold temperatures.

Some rootstocks influence the size that the tree will ultimately attain, although the mature size of the tree also depends on the standard height that’s normal for the scion or main variety. Dwarfing rootstocks are categorized by the amount of dwarfing they provide. Apple tree sizes, for example, fall into several categories:

• Standard-sized apple trees, grown on seedling or nondwarfing roots may reach 25 feet.
• Semi-dwarf is about 75 percent of the standard height or about 18 feet at maturity.
• Dwarf trees are about 50 percent as high as standard or 12-feet tall.
• Miniature trees are only about 15 percent of the standard size. At a mere 4 feet in height, these trees are the best ones for growing in containers.

As an organic home gardener, consider dwarf to semi-dwarf size trees for several reasons. Monitoring and controlling pests is easier to do when you can reach the top of the tree. On very small trees, you can even use a barrier fabric to help prevent insect infestations. You can also harvest fruit years sooner and pick the fruit more easily.
Whether you have a large yard or a half whiskey-barrel container, you can find a fruit or nut variety that fits your available space, soil, and climate by choosing the right rootstock. Specialty nurseries that ship by mail have the largest selection of varieties and rootstocks, while local garden centers usually offer only dwarf or semi-dwarf trees in a handful of popular varieties.

Sex and the Single Tree

Many fruit species, such as apples, sweet cherries, European pears, and Japanese plums, require cross-pollination to bear fruit. That means that you need two different but compatible varieties planted near one another so that the pollen of one fertilizes the flowers of the other.

The trees must bloom at the same time for cross-pollination to occur, and some varieties are fussy about who they mix with. Other fruit species are self-fruitful, which means that they can pollinate their own flowers, but even those trees often produce larger crops when they mix pollen with a friend. Reputable nurseries or your local extension office can tell you which varieties can pollinate each other.  ....read more