Tools of the Grafting Trade
Did you ever see five varieties of apples growing on one tree? Have you wondered about the difference between standard, semi-dwarf and dwarf versions of the same fruit variety? Ever see a pear growing on a quince tree? These horticultural tricks are all about the ancient art of grafting. Although shrouded in mystery, grafting fruit trees is a simple process that requires minimal equipment and effort, yet lets the home gardener grow an almost limitless number of fruit varieties on relatively few trees. In its most basic form, grafting involves inserting a piece of branch, called a scion, of one tree variety into the stem or trunk of another. This allows you to grow a multitude of varieties on one tree.
Nothing new under the sun
Grafting has been a horticultural staple for thousands of years. Records from Theophrastus, generally regarded as the Father of Botany in Ancient Greece, describe the process as far back as 300 B.C. As civilization marched across the world, these effective techniques followed. In Ancient Rome, Pliny the Elder wrote extensively of grafting practices, and the basic methods continue to this day.
In current applications, grafting and bud-grafting (incorporating single bud pieces of scion instead of a two- or three-budded scion onto a common rootstock) is critical to the fruit tree industry.
“Modern apple production is probably more sophisticated than any horticultural art,” says Dr. Ken Mudge, associate professor of horticulture at Cornell University in New York, who teaches courses in grafting trees and shrubs.
Ken says, “The rootstocks are specialized varieties that have been bred for certain characteristics.” Depending on the purpose, rootstocks are chosen for their growth habits (such as dwarf or semi-dwarf) and disease resistance. Grafting allows producers to grow a number of varieties on these standard rootstocks, producing desirable fruit while maintaining overall consistency in the orchard.
In reality, most of the trees you find at nurseries have been produced by grafting a specific cultivar to the appropriate rootstock. Growing a tree from seed takes many years to bear fruit, and it very well might not be true to form. A grafted variety will bear within two to three years, and its characteristics will be true to the variety. Jim Whitaker’s grafting hobby began more than 30 years ago at his home in Barberton, Ohio, and over the years he’s had tremendous success. “I’ve had apples the same year I grafted them,” Jim says. The new branch may not produce bushels, but it’s always nice to try the fruit sooner than later.
Jim says if you have an older tree, but don’t particularly like the fruit, it’s easier to graft a new variety to it rather than pulling the tree out and planting a new one. Plus, it won’t take as long to enjoy the benefits.
The other advantage of grafting is growing the variety you want since many fruit tree cultivars were derived as vegetative sports and won’t reproduce seed that’s “true” to the parent. Typically, if you plant a half-dozen apple seeds from the same tree, no two will come out the same. Grafting ensures you’re able to enjoy the fruit you desire.
Give grafting a try
Regardless of the long and illustrious history, don’t be afraid to experiment. There is truly very little risk. If a graft doesn’t take, it dies at the union. You don’t lose the entire tree. It’s well worth the effort for impressive – and delicious – results.
Want to try an heirloom apple, such as Jonagold, but are concerned about its susceptibility to fire blight? Graft a Jonagold scion onto an established tree. If it succumbs to the disease in a few years, you still have the original tree. If you are unsure about which new apple to add to your orchard or are short on space, you might sample the fruit from a graft before investing in a new tree..
Jim and his wife, Joan, traveled to the Cornell University fruit-tasting station when he became interested in grafting in the 1970s and 1980s. They took several days each season sampling apples to decide which varieties to try at home. “It took 10 years to taste them all,” he says. “They had 1,500 varieties with names and 700 to 800 with numbers.”
During his most productive year, Jim enjoyed 200 different kinds of apples on the 20 trees in his yard. “On some I had five, some I had 10, and on one I had 18.” Over the years, he’s whittled down what he likes and what grows well; he now averages approximately four different apple varieties on each tree.
It’s all about relationships and timing
Although the process is fairly straight forward, there are a couple of important things to remember for successful grafting. Most important is to choose compatible species for your grafting experiments.
For instance, an orange graft won’t take on an apple root stock. “If they’re two different (phylogenetic) families, forget it,” Ken says. For best results, choose closely related species or cultivars within the same species.
Grafting different types of trees opens up exciting possibilities for the backyard orchardist. Whitaker says you can graft apricots on plums, crabapples on standard apples, and Japanese plums with the European plums without much difficulty.
The other important consideration is keeping the graft from drying out, which is why most are done early in the spring, while the tree and scion are still dormant. “The strategy is to minimize moisture loss in the tree,” Ken says.
If grafting is attempted during the peak growing time, the graft has to compete (for nutrients and water) with leaf and fruit production. Since most of the effort is diverted to these processes, the summertime graft will most likely fail.
From scion to stout limb
The first step in grafting is obtaining the scions, the short pieces of branches with two to three buds that are inserted into the understock (tree or root stock). Gathering scions, either from your own orchard, a friend’s place or from a nursery selling them, is best done in the winter – from January to the beginning of March – when the trees are still dormant.
Scions should come from 1-year-old wood, and never be larger in diameter than the branch you’re going to graft to. An ideal diameter is approximately the size of a pencil.
Using a sharp, clean knife, cut sections of branch at least a couple of inches longer than you need. Three healthy buds on each scion are preferable. Wrap the scions in damp paper towels or newspaper, and store them in a plastic bag in the vegetable drawer of the refrigerator until you’re ready in the spring. Keeping the scions in this artificial dormancy increases your chance of success because when the understock is budding, the scion will be a couple of weeks behind. This allows the scion to take before it begins vigorous growth.
The best time for spring grafting is when the buds are just ready to open, typically in April to May depending on where you live. Jim says he prefers to graft at his Northeastern Ohio location when the water temperature of Lake Erie is 45 degrees. It seems to coordinate well to time budding since air temperature can fluctuate from year to year. If the leaves are already out, it’s tremendously difficult to keep the graft from drying out and failing.
A number of grafting styles offer varying degrees of difficulty and success. One of the simplest techniques is the whip graft, although it is also more likely to fail if the graft is not kept tight. But since scions don’t cost very much, or are outright free from friends, it’s easy to practice.
For the whip graft, use a sharp knife to make an even, sloping cut roughly 2 inches long from just below the scion’s last bud to the root end. (It’s important to keep track of the top of the scion, since one inserted upside down will not take.) Make a similar cut on the branch you wish to graft to – take care that the angles of each cut match up as closely as possible. Insert the scion into the branch, and be sure the green, cambium layers beneath the bark on both stems make solid contact.
Jim says he prefers to use a scion with two buds and tries to choose those that will branch out sideways; so the limb grows to the left and right instead of vertically. After securely wrapping the joint with electrical tape, he uses Treekote®, a tree wound dressing. “You have to completely seal it,” he says.
You can also use budding rubbers, eight-inch pieces of elastic material that effectively hold the graft tight, without having to also use Treekote® or grafting wax to protect the union. You can find these items at grafting supply nurseries.
A cleft graft is similar to a whip graft although it utilizes both sides of the scion. It’s often used to attach a new variety onto an old tree by inserting the scion directly onto the top of the base stock, or onto a mature branch that is cut back to within two to three feet of the trunk.
Like the whip graft, the best size scion is roughly ¼ inch in diameter. Evenly slice both sides of the scion, keeping the end blunt.
If you’re grafting to the top of a mature tree, or even on an older branch, you might have to use a mallet to tap a sharp knife (or a special grafting tool) into the understock to widen it enough to insert the scion. Be careful not to split the wood, which could introduce disease or not allow a tight fit, causing the graft to fail.
Insert the scion into the cleft, and make sure it’s tight against the cambium at the base. Tape it snugly if it’s on a branch, or cover it completely with wax or a grafting compound where it’s impossible to tape it, to make sure there are no exposed inner layers.
Whip and tongue graft
This method takes a little more practice and can be hazardous to fingers if you’re not careful, but it offers a secure union that is more apt to withstand wind, rain and even late-season snow showers.
The whip-and-tongue graft is particularly effective on young trees; it’s best if your scion and understock are roughly the same diameter, so they line up perfectly. Slice the bottom of the scion the same as you do for a traditional whip graft using a single motion of a sharp knife to make a smooth angular cut roughly 2 inches long. Do the same to the base stock branch. They should fit together like a couple of pieces to a puzzle.
Now the tricky part: Make a vertical cut on both the scion and base stock to form a “tongue” that will hold the two pieces firmly together. Hold the piece tightly, and cut very slowly to avoid including a finger in the process. Place the two pieces together. If the cambium layers don’t touch, or your angle is off, it’s best to toss the scion aside and try again. Once you have a tight fit, secure it with tape or budding rubbers.
There’s not a lot of care after grafting. If using budding rubbers, they will fall off on their own after a few months.
Jim says he slits the electrical tape since peeling it off could damage the cambium. He recommends, once it’s obvious the new branch is growing, to “take a sharp razor blade, and go right down the middle. It will weather off.”
It’s also a good idea to mark your branches, so you remember what you added each season. Jim uses metal tags wired around the branch indicating the type of apple.
You can keep as detailed records as you’d like, keeping track of where you obtained the scion, when it was grafted, the technique used and the results. Although it might not seem terribly important when you first start, with hundreds of apple varieties begging to be grown, adding one more to the orchard can be a hard temptation to resist.