It’s easy to improve fruiting or change the variety
Grafting apple trees is a very interesting process and it’s actually easy to top-graft a new variety onto an existing tree. This can be done now on a tree that is healthy and growing well, but just doesn’t produce much fruit. Another reason might be because you don’t like the taste of the existing variety, so top-grafting allows you to completely change the variety of apple. You can also do it for fun and introduce several different apples onto a single tree to create a family tree.
Grafting should be done at the end of the dormant season, just before growth starts in early spring. The basic technique is to insert new shoots of the variety you want into the old wood, taking care to match up the cambium layer, which is the green layer just below the bark that transports sap up and down the tree. When joined together, the cambium heals over, just as a scab would if you cut your finger.
For the graft wood, known as scions, you need one-year old shoots cut into 10cm (4in) lengths. To prepare the tree, cut back the branches with a pruning saw to short stumps. All you need then is a sharp knife, electrical tape, grafting sealant such as Medo and a little patience! Fingers crossed new shoots will start to grow from the scion by late May.