Today’s topic may not be of any value to you until next spring. That is, of course, unless you have some scion wood and rootstocks sitting in the fridge at home.
I believe grafting is the most extraordinary method of propagation. Planting seed and even taking cuttings of a plant are very intuitive but it must have taken a great amount of ingenuity to discover that desirable woody plants could be maintained by lopping of the entire upper half of an unwanted member of the same species and connecting a piece of the plant you want to keep.
Without grafting there is no easy way to reproduce many fruits true to type. Because of the way these fruits reproduce through cross-pollination you could take the seed of a specimen that you wanted to reproduce, say a macintosh apple for example, and if you planted its seeds you would grow a wide range of apple trees none of which would be a macintosh. There are whole forests of apple trees in southwestern Kazakhstan but the great genetic diversity on display there means very few have fruit that is worth eating.
The fruits that we have grafting to thank for include apples, pears, figs, olives, cherry and peach to just name a few. Grafting probably has its origin in the ancient middle-east. The grafting of olives is even used as an allegory in the bible in Romans (11:17-24).
I would like to show you how to do the easiest graft, the cleft graft, of an apple tree. The equipment you will need is a pair of pruners, a sharp knife, electrical tape, and optionally grafting wax.
You will also need to obtain some rootstock material. This can be obtained online or at many large nurseries. The rootstock that is selected has an important impact on the growth habit of the final tree. Rootstocks can be dwarfing if a smaller tree is desired, semi-dwarf, or standard for a full size tree. Rootstocks also vary in there cold hardiness. I purchased the rootstock below at Cummins Nursery. It is a bud 118, a very cold hardy standard rootstock developed in Russia.
You will also need to obtain scion wood. This is the technical term for the cutting of the plant you are trying to maintain. This material needs to be taken from the tree before it leafs out in the spring. It can then be stored in moist toweling in your refrigerator until you need it. The best scion wood comes from water sprouts that are growing straight up and down. Fortuitously you don’t want these on your established tree anyway so you’ll already be pruning them off. The scion wood that I am using comes from an unknown heirloom variety from an old farm owned by a friend.
Now you will need to prune back the rootstock. You want as few of the rootstocks buds to remain as possible while leaving about an inch and a half to place your graft about the rootstocks roots. After that you want to split the stem of the rootstock down the middle with your knife for about an inch.
Please note that the above picture is just for demonstration purposes, the rootstock in the picture is just a scrap piece which is why it's upside down.
Next you want to form the bottom of your scion wood into a wedge as long as the cleft you created in your rootstock. This is where the sharpness of your knife really matters because you don’t want to tear off any of the bark or even muss it up. I like to leave four viable buds on my scion wood. If you leave too many buds that leaf out then the demand for water may be too great for your new graft to handle.
Now you want to insert your wedge into the cleft. The important point here is to match the inner green layer of bark on the two pieces. This layer is called the cambium and it’s where water and nutrients are moved so we need them to join together in the graft.
Electrical tape around the whole graft tightly so that the two pieces are pressed together and that no moisture can escape. If you want you can seal the bottom and top of the taped off areas with grafting wax.
The newly grafted tree needs to be stored in the fridge for a few weeks to heal. Remember to keep it moist. When you are ready to pot you will want to soak the roots for a few hours. Keep the plant well watered and also water around it to keep up moisture levels until the buds pop open.
The pictures below are of a one year old pear tree graft that I did. You can clearly see the wedge of the scion wood and where a callus has grown.
Now that you have the basics down many more options are available to you. You could graft many different varieties onto the limbs of an established tree. You could experiment with other grafting methods such as tongue and whip. Maybe you want to save an old apple from the family farm for future generations.
I wish you luck in your grafting endeavors. On a side note, the next topic of discussion will be magnolias.