Hi folks,
I just answered an email question from someone, about using a grafting knife. He had asked if it wouldn't be easier for a right-handed person to use a left-handed knife, so he could make the cuts away from his body, thus being safer. I thought my reply might be helpful to some who read this forum as well, so here it is:
No, I would have to disagree. I'm left-handed, and I always use a left-handed knife.
One of the problems with grafting is that it requires very fine-muscle motor control, to get the very precise cuts needed, and by the nature of human hands and arms, you get much better control when pulling toward yourself, than when pushing away. So yes, grafting cuts are always made by pulling the knife blade toward your body. I've never met a successful grafter who pushed away in making the cuts; it seems to be impossible. The way you hold the knife and the scion stick will then determine whether you'll cut yourself. Done properly, wounding yourself is not at all likely. So here's how:
1. Hold the knife in your right hand, sharp edge of the blade facing your chest.
2. Middle, ring, and little fingers should grasp the handle of the knife, wrapping over the top of it; index finger should lie on the top (non-sharpened side) of the blade. Thumb should hang free, between the blade and your chest.
3. When cutting, that thumb protects your body. NEVER use your thumb to push the scion into the knife; you'll end up with a split thumb. Rather, use it to guide the direction of the scion, but keep it rigidly away from the blade (under some muscle tension to avoid going into the blade). If the knife slips out of the scion wood and flies toward your chest, your thumb will hit your chest first, stopping knife movement. By holding some muscular tension in the thumb AWAY from the blade, you also cannot cut the thumb (most likely wound by beginning grafters) during a slip of the knife.
4. Your left hand will hold the scion. ALWAYS hold the scion ABOVE the point you plan to cut, so that you are pulling the knife AWAY from your left hand, never toward it. If the scion stick is long enough, I tend to press the base of it into my sternum, sort of as a "third hand." I'm still protected there, by my knife thumb. If both hands are held in proper position, you simply cannot cut any part of either hand, and the knife thumb protects your chest. Until it becomes automatic habit, think about that every time you make a cut -- is any susceptible part of my body in front of that blade? If so, I'm doing this wrong.
5. When cutting the understock, there are two possible methods. Many grafters make their cuts bottom-to-top, in which case they lean over the top of the plant, and work on the far side, pulling upward in the "normal" direction, relatively to their face and chest. However I've never liked that method. Instead, I work with the surface to be cut at nearly eye level (I grow my understocks in pots, so they can be placed on a table). I hold the stock stem with my right hand (your left hand), keeping all 4 fingers BEHIND the stem, so that the stem protects the non-knife hand from cuts. Then, holding the knife as described above, I make the downward cuts. Depending on the type of cuts, it is often convenient to reach around with the thumb of the non-knife hand, placing it on the top of the tip of the knife blade, for more strength and guidance at that part, for a very smooth, clean cut. Using this method, the cuts are made top-to-bottom on the rootstock.
6. If I'm working with a non-toxic plant (citrus, roses, etc.), I normally cut the scion first, then store it in my mouth while working on the rootstock. One of the biggest problems beginners have is that the cuts must be made perfectly and quickly -- a difficult thing to accomplish. Yet even a few seconds in warm, dry air may be long enough to kill a layer or two of surface cells in the cut, and doom the graft to failure. A scion can easily dry out while you are working on the stock, unless you're very fast at it, and that only comes with much practice, like any skill. So, by storing the scion in your mouth, you can keep it alive for several minutes, if necessary, until the stock is ready. Saliva is harmless, perhaps even protective, of scion cuts. I've had colleagues who were disgusted by the idea, so they used dampened paper towels, a glass of tap water, boiled water, etc., to prevent drying of the scion. In each case, their graft failure rates were quite high, whereas people who use spit tend to get excellent rates of success.
If the scion is toxic (mango is a good example), I make the stock cuts first, then simply make the scions cuts very quickly and get the graft wrapped in as few seconds as possible. That may be why mango is considered harder-than-average to do successfully. So I'd recommend practicing on other species first, and when you become very fast and accurate, try some of the species that ought not to be put in the mouth.
As for making the cuts themselves -- most beginning grafters have a bit of trouble, in that they try to pull the same spot on the knife blade through the wood, and it has a tendency to catch and jerk, making a rough cut. Instead, try to start at the base of the knife blade (next to the handle), and make a single, curving, sweeping slice through the wood, ending out near the tip of the blade. This action also requires practice, because it is not intuitive or natural-feeling to the beginner. It's a skill that comes with practice. By using the entire blade, you can make a very clean, splinter-free slice, far more likely to survive.
