Grafting 102
THE PROCESS
Hopefully, a picture says a thousand words.
To the left is pictured a slice taken out of a scion, and an identical slice taken out of a rootstock. Visible in the very centre of each peice of wood is a portion of wood called heartwood. This would have been formed in the first season of growth. The pale layer of wood is pith. The outermost pith is made up of xylem and phloem, the part of the wood that transfers nutrients up and down a branch, and as these segments die and move out, the trunk expands and the pith forms a growth ring. Just outside of the xylem and phloem is the cambium layer, the part of the wood which heals cuts and abrasions. It will appear green. This last layer is the most important to remember and recognize in grafting. On your graft, the cambium layers of both rootstock and scion must meet in a firm bond.
To view cambium from a different angle, take any wood formed last year on a healthy shrub, and scrape back the top layer. The green layer is the cambium layer. You can tell if a branch is alive or not with this simple method.
This graphic also illustrates one of the simplest types of grafts, called the splice.
In this graphic, the two sides of the above splice are shown bound together. The tape used is grafting tape, also sold in some countries as budding rubber. Grafting tape is not sticky. This material provides an excellent tie for the two sides of the graft, and degrades after a few years leaving nothing to bind the successful graft.
You can also use electrical tape or florists tape, but the results and ease of removal are not as good. Electrical tape in particular is generally too wide and doesn't breathe well. Additionally, because the mentioned tapes are sticky, sometimes they collect debris and trapped insects, which can in turn cause the onset of rot.
All types of grafting use some form of binding. In the following graphics I have illustrated the grafts themselves, but will leave the images of those particular grafts taped up to your imagination.
This particular graft is called a Cleft Graft. In this, the rootstock is considerably larger than the scion. If you are grafting onto an existing tree, this is the method you should use. Not only is this method easy, requiring a minimum of fancy cuts, but it will also make use of the watershoots many gardeners will be pruning off their trees at pruning time. Make friends with someone with a scion you want, and pop round when they are pruning. Take your scion home.
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