As I managed to get some time to work on my trees this last weekend, I though it was a good opportunity to do some grafting before my black pines woke up too much. I like to do grafting on black pines just before they start moving in spring. For bud grafting this is important as once the sap starts to move in a big way any cuts made to hold grafts tend to flood with sap before placing the scion which makes them a little less successful. Approach grafts on the other hand are a little more forgiving but if I can I try to do them around the same time so that the burst of energy that comes with the first flush of candles extending goes into healing the graft site.
I have decided to graft this tree as it has a rather large bare section of trunk. If I can graft a new leader to the base of this I can build a much smaller and more compact tree with the new graft’s growth. Obviously this will be a longer term project but I figure why go down a long road just to end up at a mediocre tree. If this graft takes and the tree develops as I imagine it will be a far greater result in the future than had I just persevered with the existing structure.
The first step is to create a cut for the graft branch to sit inside. I like to make the cut about 1/4 smaller than the branch that is going to be inserted into it. I start by making the cut with a small saw. I try to make the cut so that it is wider at the rear of the cut than at the front edge. usually this takes two cuts, one slightly slanted upwards and a second slightly downwards. This flared cut will help the scion branch to lock into the cut.
Once I have made the first pass with the saw I clean up the cut with a knife so that I have clean and neat surfaces upon which the graft can be placed.
Next I remove a small slither of bark from either side of the scion branch. Make sure that you check where to make these cuts prior to getting the knife out as it is important that these cut surfaces line up with the cut surfaces you made with the saw. I usually find that the knife cute that clean up the saw cuts combined with the cuts on the scion branch tend to eliminate the 1/4 under size that was initially cut with the saw.
The Scion branch can now be inserted into the cut in the trunk. The fit should be snug and tight. Small adjustments might be needed to be made to the channel in the trunk to make sure things are all snug. If the channel is on the large side it is best to chock the scion branch so that it contacts firmly with the lower surface of the channel cut. (I use small twigs as chocks.) As sap runs from the roots up, contacting the lower surface will ensure that the graft has a better chance of taking than had it only contacted the upper surface. Either way, the scion should be firmly touching at least one cut surface on the channel in the trunk.
Finally you simply seal the graft union and hold the scion firmly in place so that it cannot move and disturb the graft before it has had a chance to take.
The speed at which the graft takes will depend on the amount of growth you allow to occur on the scion branch and above the graft site. Obviously the more the trunk and scion branch grow and expand the more chance the graft has of taking. I would hazard a guess that this graft will be taken by the end of this coming seasons growth. Having said that I will probably cut off the growth above it in stages so it may be two seasons before I actually sever the scion branch from its original source.