Grafting

Why Graft a Tree Rather Than Take a Cutting?

While the scion determines the variety of fruit a tree will produce, the rootstock determines the size, vigour, disease resistance, the type of soil conditions it can handle, and to an extent the longevity of the tree.

Also, fruit trees grown on commercial rootstocks tend to produce trees that fruit within a year or two, rather than having to wait the 3-8 years it takes to get fruit from a tree grown from seed. Fruit grown from seed does not necessarily produce the fruit the same as the parent. 

What Is A Rootstock and what is a Scion?

Which rootstock to use?

Compatibility

The first consideration when selecting a rootstock is compatibility. The general rule of grafting is like to like. If the rootstock and scion are from the same genus they are generally compatible. So Malus, apples on apples, Juglans or walnuts to walnuts. There are some exceptions though.

For instance, pears which are of the genus pyrus are often grafted onto quince, which is cydonia. On the other hand, Almonds, Apricots, Peaches, Nectarines and Plums are all of the Prunus genus, but not all are compatible. In general, many European and Japanese plums may be grafted on most European plums. Although many Japanese cultivars do well on other Japanese cultivars, European cultivars are not successful on Japanese stocks. Peaches, almonds, and apricots may sometimes be grafted on Japanese and European plums with reasonable success, but, as a rule the grafts either fail to grow or do not grow satisfactorily.

Interstock: Some varieties of fruit may graft successfully and others not. Pears are a common example of this. To get around this incompatibility you can use an interstock. That is a graft in between the rootstock and the scion that is compatible with both. This generally takes two seasons to graft, one to graft the interstock, and then the following season to graft the desired scion. 

Now you may be told that you can graft a pear on an apple or make a tree with plum, apricot, and peaches on it. And this can be true. But there is a reason why commercial nurseries do not do this. The grafts are often unreliable or short lived. But if you want to experiment on your own trees, give it a go and see what works. If you are growing for yourself then you have nothing to lose, and maybe a unique tree to gain.

Here is a list of the generally recommended grafting compatibility:

Physical Characteristics

Another consideration in choosing a rootstock is to control the size of the tree.

It should be noted that generally the more dwarfing a rootstock, the shorter the lifespan of the tree will be. For instance, pear trees on pear rootstock can live for over 300 years. For example the Kerikeri Pear tree which is over 200 years old. However pears on quince rootstock have a general life expectancy of around 40 years.

Lastly, you may want to choose a rootstock that will give the tree some advantage, such as disease resistance or one that will perform better in your local soil conditions

How grafting works.

The cambium layer is a critical part of a tree's vascular system. It is a thin, delicate tissue that resides just beneath the bark of a tree. This layer is responsible for the growth of new cells and tissues, making it one of the most crucial components for grafting success. When grafting, it's essential to ensure that the cambium layer of the scion (the upper part of the tree) lines up as closely as possible with the cambium layer of the rootstock (the lower part of the tree). This alignment is often achieved through precise cuts and careful positioning of the scion on the rootstock. While certain trees, particularly apples, can handle less precision in this alignment. If the cambium layers aren’t connected somewhere the graft will not take. 

Cleft graft

Grafting fruit trees using a cleft graft is a common technique for propagating new fruit trees or repairing damaged ones and its what I am going to teach you today. There are other methods of grafting, and I generally prefer a whip and tongue graft. You can find good video from Jason van den Bemd showing how to graft using the whip and tongue method in our Helpful Resources page. Which you choose is up to you, but certain methods work better in certain situations. 

For instance, a cleft graft can be better when topworking an existing tree, or adding scions to a branch or rootstock that is much thicker than the scion. Bud grafting, which is an advanced technique, involves slipping one bud from the scion, under the bark of the rootstock. Bud grafting is the usual method of grafting citrus and stone fruit in summer. The whip and tongue is a reliable method to use when your scion and rootstock are similar thicknesses. 

Materials You'll Need:

• A healthy rootstock tree (the tree you want to graft onto).

• A scion (a healthy young branch or shoot from the desired fruit tree variety).

• A sharp grafting knife

• Pruning shears.

• Grafting wax or tape.

Step-by-Step Instructions:

Select the Right Time:

Grafting is typically done during the dormant season, in late winter or early spring, before new growth begins. This is when both the rootstock and scion are in a resting state. For the graft to survive the rootstock needs to be coming out of dormancy, i.e. the sap is flowing again after winter, in order to supply the graft with the water and nutrients it needs once it begins to grow. 

Prepare Your Tools:

Ensure that your grafting knife or pruning shears are clean and sharp. If working across multiple trees it is good practice to sanitise your shears with methylated spirits or similar when moving between trees to prevent any spread of disease.

Monitor and Wait:

Keep an eye on the graft union as the growing season progresses. New growth from the scion should emerge from the graft site.

Once the graft has successfully taken and the scion has grown sufficiently, you can remove grafting tape. I recommend that you leave this on as long as possible, up to a year unless you see that the tape is beginning to restrict the growth of the tree.

During this time the rootstock will also likely produce new buds and branches. Leave these on until you are sure that the scion has taken successfully. This way, if the graft is unsuccessful the rootstock will likely survive and you can re-graft it the following year.

Prune and Care:

In the following seasons, carefully prune away any unwanted shoots or branches that emerge from below the graft union. For the first year or two remove any blossoms and fruit otherwise you will stress the graft. 

Provide appropriate care, including watering, fertilising, and protecting the tree from pests and diseases.

Get Grafting

Grafting can be a rewarding way to propagate new fruit trees or change the variety of an existing tree. It may take some practice to master the technique, so don't be discouraged if your first attempts are not perfect. Over time, you'll become more skilled at grafting and producing healthy fruit trees.