Grafting season is just coming to a close, but I wanted to take this opportunity to explain why and how grafting is done, and show a few photos from some apple trees I grafted last Tuesday in North Seattle.
Every specific variety of apple, orange, plum, cherry, grape, kiwi, etc. that you eat is genetically identical to the other of the same name. These fruits are not grown from seed, but instead are grafted onto another tree or “rootstock”. One of the reasons this is done is that there is a lot of genetic diversity in many fruit seeds, so you’re not likely (in fact almost guaranteed not to in the case of apples) to get an entirely different fruit if you planted a seed. Although in some fruits, for example stone fruits (plums, peaches) there is less variation from seed so planting these pits may actually give you a relatively similar fruit. Some specific varieties of fruits such as oranges or grapes have been bred to be seedless, so grafting is the only way to propagate these types.
Grafting consists of connecting the tissue of one plant onto another so that they grow together. I’ve had the most success using the whip-and-tongue or whip graft. A piece of scion wood (the wood from the desirable plant) is cut in a certain way and fitted onto the rootstock or the branch of an existing tree. The graft is wrapped in special tape and the ends are sealed with wax or tar to retain moisture. After several weeks the graft should have grown together and the buds on the scion wood will begin to grow. With this method it’s possible to have many varieties of fruit on one tree. There are many advantages to this such as proper pollination, or to lengthen the season over which the fruit ripens. For example you could have five different varieties of apples on one tree. A Williams Pride which ripens in August, followed by an Akane, Pink Lady, Honeycrisp, and finishing off the season with a Braeburn which ripens mid to late October.
Another type of grafting called budding can be done in mid summer. This involves taking a bud from a desirable tree and slipping it into the bark of a branch or another tree after making specific cuts into the bark. So if you’ve missed this grafting season, you can still add another variety to your fruit tree this summer.
The Seattle Tree Fruit Society has a nice web page with useful links if you’re interested in learning more about grafting.