Last week I wrote about why fruit trees were grafted to produce shorter specimens. A few people asked me exactly how it was done and the best time to do it.
As usual, questions like that seldom produce a simple answer. There are several techniques and they generally aren’t all performed at the same time of year. Cleft grafting is probably the appropriate choice in most situations. Cleft grafting is best performed when the stock (lower part) is beginning active growth in the spring. The scion (upper part) should still be dormant.
The first step is to obtain dormant scion wood about as big around as a pencil from the tree variety you want a few weeks before grafting. Some people even collect scions in early winter. Store them in the refrigerator. Choose a spot on the existing tree where the trunk is about two to four inches in diameter and clear of any side branches.
When the tree’s buds begin to swell it’s time to graft. Start by sawing off the stock at a 90 degree angle. Split the trunk with a chisel, hatchet or specialized grafting tool. Install a narrow but thicker wedge in the middle to spread and hold the split truck apart. Now you’re ready to install the scions.
The next few steps are the ones that are critical to success. Clip your dormant scions so that when installed there will be two buds above the graft. Each graft requires two scions. Taper the sides of the lower two to three inches of the scions to form points. Make sure the tapers are slightly pie-shaped so that the thicker side can be toward the outside.
Now comes the most critical step. Press the two scions into the stock making sure the inner bark layer of the stock and scion line up perfectly. This region is what we call cambium tissue. It is a place of rapid cell division where tissues can merge because they are not specialized. Remove the center wedge so the stock will grasp the scions tightly.
Check to make sure scions are still straight and cover the entire area including scion tips with grafting wax. It has a low melting point. Tree wound dressing works but not as effectively. Try not to get any wax on the young buds.
In a few days inspect each graft, and apply more wax if necessary. Stocks will begin to sprout beneath the graft. These suckers should be removed. Remove side shoots from new scion growth too. This makes grafts less wind susceptible. Some people even stake the new growth. After the first season clip off the weaker of the two scions. Leaving both new stems results in a poor graft union. In two or three seasons the trees should begin to fruit.
Some people use this cleft graft technique to attach a single scion to a much smaller stock. Both pieces are usually about pencil sized and the scion taper is evenly opposite and not slightly one-sided.
This is only one of many techniques used to topwork fruit trees. Another is called t-budding. It is done during active growth. I’ll address that technique next summer.
Ted Manzer teaches agriculture at Northeastern High School.