Gardening Articles: Edibles :: Fruit & Nut Trees
by Kris Wetherbee
Grafted citrus trees in containers
Grafting is the process of connecting two different plants so they grow as one. The advantages of grafting include combining attributes that don't naturally occur in a single plant, for instance flavorful fruit with dwarfing or disease-resistant roots. All grafts are composed of two parts: the detached part of one plant, called the scion, which becomes the flowering and fruiting top part of the plant; and the rooted and growing part of another plant, called the rootstock.
Over the years many grafting techniques have evolved, but the whip-and-tongue graft is favored by most professionals who propagate fruit trees. It works best when both scion and rootstock are small (1/4 to 1/2 inch in diameter) and the same size. In part because of the added surface provided by the tongue, this graft heals fast and forms a particularly strong union. Much experienced in the technique is Nick Botner, a hobby orchardist in western Oregon, who guided this article.
The whip-and-tongue grafting process begins in early winter once plants have become fully dormant and growth hormones are concentrated in next season's buds. The only tools you need now are bypass pruning shears to collect the scions and a plastic bag in which to store them. Although you won't be grafting for several months, choose scions of the same diameter as that of your well-established rootstock (which should have been planted one year earlier). Select scions that are about pencil thickness, 6 to 8 inches long, with three or four buds. Label them by origin and with the variety name, and be sure to indicate the top and bottom. Refrigerate the scions in plastic bags until early spring.
The ideal time to graft is between January and March, just prior to the natural burst of spring growth. To make clean cuts, you'll need a sharp, sterile knife with a flat (not beveled) blade. (See Steps to A Successful Graft, below.)
Within a month after grafting, expect new growth from both rootstock and scion. The rootstock will send out suckers during the first year. Remove them down to the very base of the tree to redirect the energy from the tree's roots into the scion. On the other hand, leave new scion growth untouched until the longest is 6 to 8 inches, normally toward the end of May. At this point, select the best shoot to form the main trunk of the new tree. Pinch out the growing tips of the other shoots, leaving five or six leaves on each shoot to aid the formation of a strong union. (In fall, cut away these pinched shoots.) Also in May, remove the binding by running a sharp knife up the back of the rootstock, taking care not to injure the bark. Water your grafted tree weekly throughout the first year.