What is the Magic Behind Fruit Tree Grafting?

Have you ever wondered about the magic behind grafting fruit trees? Jesse Imbach, a member of the California Rare Fruit Growers Association, explains more about his upcoming grafting class (January 30, 2016, from 2 PM to 4 PM) on orchard alchemy.

What is grafting?

Grafting is the technique of physically inserting the living tissues of one plant into the living tissues of another closely related plant so that they grow together as one. As long as the vascular tissues of both plants are able to make a solid connection, the introduced tissue will grow with the rootstock as a single plant.

Generally, it is possible to graft together two plant species in the same family. However, some plants grow better together than others. So while it is common to graft a fruiting pear to the roots of a quince, specific varieties of each of these fruit trees may grow better together. The best way to find out what grows well together is to give it a try.

So, now that you know it’s possible to produce Frankentrees in your own backyard, why on earth would you want to?

Why graft fruit trees?

The easy answer is: to clone a tree you really like! For example, if I plant 100 seeds from apples on my mothers favorite old apple tree, plant 100 seeds from a Granny Smith apple, because of the diversity of genetic material in each seed, I may have a 1:100 chance of getting a Granny Smith tree. There will be 99 other trees, each a little different, but I won’t know what type of apples they will produce until the trees are old enough to produce fruit, which could be anywhere from 3 to 10 years!

That doesn’t mean you shouldn’t plant those seeds however. Seedlings produce strong roots, which in grafting we call rootstock, and by attaching a bud or shoot, which we called a scion, from a Granny Smith tree to the rootstock, we can be sure to get another Granny Smith tree. We’ve created a clone.

As an added bonus, the cloned tree will also produce fruit much faster than the trees grown from seed — often in as little as a year after grafting. In addition, grafting makes it possible to grow many different fruits on a single rootstock. Thus, the grafting process allows gardeners to reproduce favorite plants with consistent characteristics, enjoy early fruiting, and potentially have many types of fruit on one tree.

While not a part of the upcoming class, by cloning rootstocks, we can also select for certain characteristics in the overall tree, like dwarfism, cold hardiness, water sensitivity, or ability to withstand heavy or sandy soils. By grafting favorite shoots to cloned rootstocks we can create trees with particular strengths that are useful in different environmental conditions, and we are thus able to grow that Granny Smith apple well outside the climatic conditions of the ancestral genetic home of apples… Kazakhstan.

This means that grafting is not about creating new varieties of plants, even though some characteristics of the combined grafted plant may be passed on genetically via seeds. Rather, grafting is the process of creating clones with specific strengths and compromises ideally suited to the conditions in which we wish to grow them. So, for diversity, plant seeds; for consistency, graft.

Creating grafts is really simple, if not necessarily easy, and there are many different ways to connect up the tissues between plants. All you really need is a sharp knife and a way of keeping the union from moving and drying out. In January 30th’s Common Ground grafting class that I’ll be leading with James Lalikos, we will cover a number of different techniques and demonstrate them in the hands-on part of the session. (Make sure to sign up early for this class. Check it out by clicking here!)

Basic Grafting Union Types

– Bud Graft: This graft is performed late in the season, when the rootstock is growing, but uses a dormant bud, collected and stored in the winter. The bud is removed from the scion shoot and inserted into a very shallow cut in the rootstock of the tree. To keep the union from drying out, the bud is sealed in place with wax, tape, or other wrapping.
– Cleft Graft: This graft is performed in early spring just as the rootstock is coming out of dormancy. The rootstock is cut to the height preferred and split in half down an inch or so to create a V shape slot. A scion is cut into a coordinating V shape and inserted into the slot. To keep the union from drying out, the scion is sealed in place with wax, tape, or other wrapping.
– Tongue Graft: Also called a Whip Graft, this graft is also performed in early spring, just as the rootstock is coming out of dormancy. This method is preferred by professional grafters but is also difficult for new grafters. Have patience. The scion and the rootstock should be the same diameter, ideally about a centimeter. Both the scion and the rootstock are cut at matching angles, and the tips are notched so that they intersect. To keep the union from drying out and also to ensure it doesn’t move, the scion is sealed in place with wax, tape, or other wrapping.
In all cases, the living layers of both the rootstock and scion must be in contact. In trees, this living layer is called cambium. It is the thin green layer just under the bark. This is the area of the tree that is actively growing. It is the vascular tissue of the plant.

So how do you know what to graft?

In the Bay Area, the annual fruit tastings at Andy Maraini’s orchard in Morgan Hill are amongst the greatest discovery zones for finding out about new and delicious fruit. There are literally hundreds of fruit to taste; every kind of cherry, apricot, plum, nectarine, or peach you can imagine. Each time I visit, I keep notes of all the varieties I enjoyed, and I rank them with a star system. There are a number of pome fruit orchards in the Santa Cruz mountains that also allow tasting of apples, pears, and quince. The following winter, I take my notes to the local Rare Fruit Growers Scion Exchange. (These events are open to the public and are held in January.) While there are a few varieties I’ve never successful located, (including an experimental hybrid which was never named for market) over the years I’ve managed to collect over 100 different fruits on my property with this method. Some grafts take well and seem ideally suited to my garden conditions; others never make it. The fun part is annually tasting your way though the options and hunting for the attendant scions to try your hand at each one.

Grafting–it turns out–is the easy part. The hard part is figuring out which varieties of fruit you want to grow!

Guest blog author, Jesse Imbach, loves nothing more than perfect seasonal fruit. His modest home is taken over with experimental grafted trees and rare fruit varieties from around the world. Don’t miss his upcoming class!