The fine art of grafting is really pretty simple
Holliston, Mass. — It took the veteran horticulturist and lecturer perhaps 2 1/2 minutes to split the understock, whittle two scions to shape, insert them in the split, and apply the binding tape.
Within a few seasons the Red Delicious apple tree would bear large, crisp Northern Spies as well. It could have been made to bear Bartlett pears, or any other apple -- even quince species -- just as readily.
E. Dexter Davis was making a point: Grafting one species of tree onto another is no big deal. Moreover, it is a decidedly valuable skill for a gardener to acquire.
With a little basic knowledge, plus practice, you will soon master the art of grafting. "Even a beginner should have a 50 percent success rate with his grafts," Mr. Davis says.
Indeed, a Russian agriculturist many year ago proved how simple grafting really was when he cut the bottom half off two green tomatoes growing on separate vines. Then he switched the two halves around, attaching each half to the other top, holding them in place with a couple of rubber bands.
Within a weeks the rubber bands were removed and the tomatoes grew to maturity and ripened. Tomatoes, by the way, have been grafted onto potatoes, and even a sunflower has been made to grow on a melon vine.
Intriguing experiments with vegetables aside, the principal interest in grafting concerns woody plants -- roses and fruit trees particularly.
The methods of grafting are many: whip, cleft, bark or rind, budding, saddle, and so on. The method Mr. Davis chose to illustrate on this occasion was the cleft graft, one of the simpler methods for the beginner.
Placing his pruning knife across the center of the stock, he cut straight into it to a depth of about an inch and a half. Then, after shaving the bottom half of two scions into wedge shapes, he inserted these into the cleft, one at each end. Ultimately, if both scions take, one of the new branches will be pruned out to allow the chosen scion to develop fully.
Why make two grafts where there is room for only one new branch? "To double the chance of success," Mr. Davis replies.
The important part of this operation is to see that the soft cambium tissue just beneath the hard outer bark of both the scion and the stock comes into contact. It is this layer of material that contains the minute channels through which the tree sap flows. If the graft is to take, the sap must be able to transfer from tree to scion and back again.
At this stage, Mr. Davis eschews tradition by ignoring grafting wax. He prefers a relatively modern invention: Electrician's tape. The tape is strong enough to hold the graft in place, yet flexible enough so that it will never dig into the bark and cut off circulation. Moreover, it is waterproof.
Mr. Davis begins the taping about an inch below the bottom of the cleft, each wind overlapping the other by about half. The taping is continued about an inch up each scion and is concluded by coming two or three times over the top of the understock between the two scions.
Mr. Davis suggests the novice grafter select branches 2 to 2 1/2 inches in diameter for the understock and scions, which vary from 1/4 to 1/2 inch in thickness.
The best time of year to graft is in the late winter and early spring, when the sap is rising and before the buds have begun to break out. You can make grafts even when the leaves are fully out, he says (with citrus trees, you have no choice), but he doesn't recommend this practice. The success ratio is usually much lower in summer.
In the North the best time to graft is March through April, to about the middle of May, Mr. Davis suggests. The farther south you live, the sooner you would begin grafting.
For the first three years it is advisable to keep the grafted branch from fruiting. The graft union may lack the strenght at this stage to support fruit.
When grafting a new species onto an old tree, be sure to leave many of the old branches, so that there will be a good leaf cover on the tree. Remember, it is the leaves that feed the tree; therefore, the more there are, the better.
After cutting scions from another of your trees, or perhaps from a neighbor's tree, place them in a plastic bag or in slightly moistened sawdust to prevent the lower end from drying out. If the cambium is quite dry when the union is made it will be unable to accept the rising sap.
If you become serious about grafting, you will find several good books on the subject at your local public library.Meanwhile, don't hold back. Try your hand at grafting the simple cleft way.