Enough of the stories and back to the vineyard and a lesson on grafting vines brought to us by Pete Anderson, who knows more about grape varietals than just about anyone in San Diego. Pete, among other things, teaches a course on vineyard management at Mira Costa Community College and last Saturday gave his students a demonstration on grafting at his backyard laboratory. As a guy who still can't tie a slip knot (and working on my third vineyard installation), one key thing I learned from Pete is that he makes two parallel cuts into the vine where the graft is to be inserted which doubles the odds that the graft will take. (When John the Avocado Grower and I tried grafting an avocado tree last Thanksgiving we only made one cut and failed.) Pete is also an accomplished winemaker and after the demonstration (and the knives had been put away) he brought out 7 different bottles of wine to taste. (Pete generously gave each of us a bottle to take home so we didn't fight over the leftovers.) Below is a summary written by Pete on the grafting procedure along with a video clip. When doing this at home watch your fingers!
Grafting Grape Vines By Pete Anderson
TIME TO GRAFT
Field grafting should take place when the bark slips as the vines begin new growth.
1st STEP - TRUNK PREPARATION
Cut the truck to 4 inches below the desired head height. If trunk diameter is small use loppers; if not use a chainsaw.
Using a fine toothed pruning saw, make 2 horizontal cuts on opposite sides at the base of the trunk -- these cuts will relieve the sap pressure that could cause the graft sticks to be pushed out.
2nd STEP - BUD STICK PREPARATION
Prepare the bud stick of the varietal to be grafted. Make sure you prepare only the amount to be grafted that day and keep them moist.
Bud sticks usually will have 5 - 7 nodes - using hand pruner cut them into 2-bud lengths. Caution: Make sure the orientation of the cane (bud stick) is maintained upward. Just as in potting, a cane grafted in the downward orientation will not take. The lower end should be at least 2" long; the top end should be cut at a 90 degree angle not less than 1/2" above the node.
3rd STEP - TRUNK FACE CUTS
Using a grafting knife make face cuts parallel to the vine row on opposite sides at the top of the trunk. The length of these cuts should be similar to the length of the lower end of the bud stick. The cuts will remove the outer surface of the trunk exposing the cambium. At the bottom of the face cut, make a diagonal incision approximately 30 degree angle deep enough to allow the base of the bud stick to be inserted.
Make another diagonal incision half way up the face.
4th STEP - BUD STICK CUTS
Make a long diagonal cut on one side of the lower end of the bud stick the same length as the face cut on the trunk. Turn the bud stick over and make a sharp diagonal cut at the lower tip creating a sharp edge. Make a small incision on the bud stick face cut that will match the incision made on the trunk face cut.
5th STEP - FIT BUD STICK ONTO TRUNK
Tap the bud stick using the grafting knife handle into the angle cuts on the trunk. Important: Cambium layers of trunk and bud stick must be in contact. It is best to have the bud stick positioned to one side of the face cut, not centered on the face cut.
6th STEP - SEAL GRAFT
Using grafting tape (1/2" works best) tightly wrap the graft making sure the bud sticks are in contact with the trunk. Seal the entire graft area with Henry Tree Seal or similar sealant. Also, put some seal on the bud stick tip.
7th STEP - MONITOR GRAFT
In order to prevent the graft stick from being pushed out of contact with the trunk cambium, frequently check the small incisions at the bottom of the trunk to insure the sap pressure is being relieved. If any bleeding is seen in the area of the graft, new trunk cuts should be made to relieve the pressure.