Grafting Trees: An important skill for healthy and Productive Trees

Grafting is an ancient horticultural practice that involves joining two plants so they grow as one. This technique is widely used to propagate trees, enhance fruit production, and create unique hybrids.

This practice dates back thousands of years. Ancient Chinese, Greek, and Roman civilizations documented the technique in agricultural texts.

Theophrastus, a Greek botanist, provided some of the earliest written descriptions around 300 BCE. The method gained prominence because it allowed farmers to propagate desirable traits, creating resilient and productive crops.

Grafting is a technique whereby tissues of plants are joined so as to continue their growth together. The success of this joining requires that the vascular tissues grow together.

The upper part of the combined plant is called the scion while the lower part is called the rootstock. The scion is typically joined to the rootstock at the soil line; however, top work grafting may occur far above this line, leaving an understock consisting of the lower part of the trunk and the root system.

In most cases, the stock or rootstock is selected for its healthy and strong system roots and the scion is selected for its productive and healthy stems, leaves, flowers, or fruits. The scion contains the desired genes to be duplicated in future production by the grafted plant, it is mainly responsible for the growth rate and vitality of the tree, and may also affect the taste of the fruit. For each type of soil or limitation, there is a scion that is more suitable for the situation.

For successful grafting to take place, the vascular cambium tissues of the stock and scion plants must be placed in contact with each other. Both tissues must be kept alive until the graft has "taken", between 3 weeks to 2-3 months.

Among the desired characteristics of rootstocks are plants that are able to grow in difficult soil conditions. Many trees have difficulty growing in swamps, sandy soil, salty soil or soil with a lot of lime. However, it is possible to find a specific rootstock that is suitable for a certain type of soil. There are plants that are more resistant to soil-borne diseases and pests and may be used as rootstocks.

Among the desired characteristics of the scion, in ornamental trees, the shape is important to us. Starting with the general shape of the tree and continuing with the characteristics of prolonged flowering that excels in color and size, as well as the colors of the foliage and shoots.

Reasons for Grafting

Grafting serves several purposes, including:

1. Preservation of Desirable Traits: It ensures that specific traits, such as superior fruit quality or disease resistance, are replicated. So if in our land there are fruit trees with particularly tasty fruit and high yields, and next to them there are trees of the same spices but their fruit not the best flavor, we can graft between them and get trees that all yield particularly tasty fruit.

2. Early Fruiting: Grafted trees often bear fruit faster than those grown from seeds. In most fruiting trees, juvenility may last between 5 and 9 years, Juvenility is the natural state through which a seedling plant must pass before it can become reproductive. Therefore Grafting of mature scions onto rootstocks can result in fruiting in as little as two years.

3. Repair and Rescue: Damaged trees can be rejuvenated by grafting healthy scions. When a tree suffers from physical damage or disease, its ability to grow and produce fruit can be compromised. Instead of losing the entire tree, grafting healthy scions onto the damaged tree provides a way to rejuvenate it, enabling continued growth and productivity.

4. Diversity in One Tree: By grafting multiple varieties onto a single tree, growers can enjoy different fruits which ripens in different seasons on the same plant.

5. Overcoming Soil Challenges: A scion from a tree with desirable traits can be grafted onto rootstock adapted to adverse soil conditions. Grafting is a valuable technique for addressing soil-related issues that might otherwise limit the growth or productivity of certain tree species. By combining a desirable scion with a rootstock suited to specific soil conditions.

   
   

Importance of Grafting

Grafting is vital for modern agriculture, landscaping, and conservation. It:

• Increases crop yields.

• Enables the creation of hybrid species with unique characteristics.

• Conserves endangered tree species by propagating them.

• Supports sustainable farming practices by reducing dependency on chemical treatments for pests and diseases.

• Saves time and effort to get the desired yields.

Because of its advantages, this method of propagation has an advantage over other forms of propagation in several important areas:

1. Possibility of quickly examining varieties and types with unique properties - When a variant, variety or type of tree is discovered that seems to have unique properties that we desire, it is worth examining its properties as quickly as possible. Only when it reaches a reasonable size are all its properties known and grafting on a nearby plant allows for fairly rapid growth.

2. Rapid distribution of propagation material found in limited quantities and in remote locations. In most cases, the special and desired plant source is a single plant/tree that cannot be relied upon for propagation from seeds. It may not bear fertile seeds, and if they are fertile, uneven trees with great variation between them will grow from it. If vegetative propagation is required, propagation from tissue cultures is expensive and not successful in all cases. Propagation from clones "wastes" valuable plant material, and propagation by grafting (usually grafting a single bud) is more worthwhile.

Types of Trees for Grafting

Grafting is commonly used in fruit trees, such as:

• Apples, Pears, Cherries, Peaches, Citrus varieties (lemons, oranges, grapefruits), Avocado and more.

It’s also applied in ornamental and forest trees like:

• Maples, Oaks, Pines and more.

When to Graft a Tree

Proper timing ensures the best chance of a successful graft. Dormant trees experience less stress, and the low sap flow minimizes the risk of dehydration and disease at the graft site.

The ideal time for grafting depends on the type of tree and grafting method.

• Dormant Season (Late Winter to Early Spring): Most grafting is done when trees are dormant and sap flow is low.

• Budding (Late Summer): Common for certain species, allowing buds to establish before winter.

 **make sure not to graft when it is too hot.

How to Graft a Tree

1. Choose the Right Scion and Rootstock:

• Select a healthy, dormant scion (a small branch) with desirable traits.

• Choose compatible rootstock suited to your environment.

• It is best to cut the scion and graft it immediately, and not wait too long.

2. Prepare the Tree:

• Make a clean cut on the rootstock and scion to ensure a good fit.

3. Join the Scion and Rootstock:

• Use techniques such as:

  • Whip and Tongue Graft: Ideal for small branches.

  • Cleft Graft: Used for larger trees.

  • Budding: A single bud is inserted into the rootstock.

4. Secure the Graft:

• Wrap the union with grafting tape to hold it in place and protect it.

  Use grafting tape, parafilm, or a rubber band to secure the scion and rootstock firmly together.

• Ensure no gaps remain where air or water could enter.

5. Seal and Monitor:

• Protect Against the Elements: If the graft is exposed to intense sun, wind, or rain, consider wrapping it loosely with aluminum foil or a paper bag for shade and protection.

• Monitoring the Graft: Regular monitoring ensures that the graft is healing properly and allows you to address issues promptly.

What to Look For

1. Signs of Success:

   • Callus Formation: A healthy graft will produce a callus (a protective tissue) at the union within a few weeks.

   • Budding or Leaf Growth: New growth from the scion indicates that the graft is taking.

2. Problems to Watch For:

   • Drying Out: If the scion or graft area dries, the graft may fail. Reapply wax or tape if needed.

   • Infection or Rot: Check for discoloration, foul odors, or mushy tissue, which could indicate fungal or bacterial infections.

   • Weak Union: If the graft appears loose, reinforce it gently without disturbing the healing process.

Maintenance Tasks

• Remove Wrapping: Once the graft has healed (4–8 weeks, depending on the species and method), remove the tape or wrap to avoid girdling.

• Prune Excess Growth: Remove any shoots or suckers from the rootstock to ensure the scion receives all nutrients and energy.

• Support the Graft: If the scion is growing rapidly, provide support to prevent the graft from breaking under its weight.

  
  

Different Methods of Grafting

Grafting involves various techniques, each suited to specific plant species, tree sizes, and purposes. Below is an overview of the most common grafting methods, their uses, and how they are performed.

1. Whip and Tongue Grafting

• Suits for: Small, young trees or thin branches of the same diameter 

• How it works:

  • Both the rootstock and scion are cut at an angle to create a matching surface.

  • A tongue-like notch is made in each piece to interlock them, increasing the surface area for contact.

  • The joint is secured with grafting tape and sealed with transparent tape.

• Advantages:

  • Strong union due to increased surface contact.

  • The interlocking 'tongues' add structural support to the join as the cambium layers heal and fuse together, as well giving a larger surface area of cambial contact

  • High success rate when the rootstock and scion are compatible.

    
    

2. Cleft Grafting

• Suits for: Large trees or thick rootstocks that need to be grafted with smaller scions.

• How it works:

  • The rootstock is cut straight across, and a deep slit (cleft) is made in the center.

  • One or two scions, cut to a wedge shape, are inserted into the cleft.

  • The graft is tied and sealed with transparent tape.

• Advantages:

  • Allows for the introduction of multiple scions to a single rootstock.

  • Ideal for rejuvenating old or damaged trees.

    
    

3. Side Grafting

• Suits for: Ornamental trees, or when you want to change a single branch of a tree.

• How it works:

  • A slanting cut is made on the side of the rootstock.

  • A scion, cut to a matching wedge shape, is inserted into the slit.

  • The union is tied and sealed with transparent tape.

• Advantages:

  • Can be done on a tree without removing the entire top or branches.

    
    

4. Budding (Bud Grafting)

• Suits for: Fruit trees; commonly used for citrus trees.

• How it works:

  • A single bud is taken from the scion and inserted into a small incision in the bark of the rootstock.

  • The union is wrapped, leaving the bud exposed.

• Types of Budding:

  • T-Budding: A T-shaped cut is made in the rootstock bark, and the bud is inserted.

    Chip Budding: A small chip of bark and wood is removed from the rootstock, replaced by the scion bud.

• Advantages:

  • Economical, as it requires only one bud.

  • Can graft more than one bud each grafting which increases the chances to succeed. 

  • Causes minimal stress to the rootstock.

    
    

5. Bridge Grafting

• Suits for: Repairing damaged trees, especially girdled trunks (when the bark is removed in a ring around the trunk).

• How it works:

  • Scions are cut to span the damaged area and inserted into the bark above and below the injury.

  • The scions act as bridges, reconnecting the flow of nutrients and water.

• Advantages:

  • Saves trees that would otherwise die from severe damage.

    
    

6. Inarching (Root Grafting)

• Suits for: Restoring trees with damaged or weak root systems.

• How it works:

  • A new rootstock is grafted onto the tree trunk or lower branches, forming a new support system.

• Advantages:

  • Revives trees with compromised roots.

    
    

7. Saddle Grafting

• Best for: When the scion and rootstock are of similar diameter.

• How it works:

  • The rootstock is shaped into a wedge, and the scion is hollowed out to fit over it like a saddle.

  • The union is tied and sealed.

• Advantages:

  • Simple and effective for small plants or seedlings.

    
    

8. Top working (Top Grafting)

• Suits for: Changing the variety of an established tree by grafting new scions onto its branches.

• How it works:

  • Old branches are cut back, and new scions are grafted using methods like cleft or whip grafting.

• Advantages:

  • Converts an older tree into a new variety without replanting.

    
    

9. Veneer Grafting

• Suits for: Tropical fruit trees or when the rootstock and scion are of slightly different sizes.

• How it works:

  • A thin strip of bark and wood is removed from the rootstock and scion, which are then matched and secured together.

• Advantages:

  • Works well for evergreen species where other methods may fail.

    
    

10. Approach Grafting

• Suits for: When both the scion and rootstock are actively growing and cannot be cut off immediately.

• How it works:

  • Both plants are brought close, and matching cuts are made on their stems.

  • The cut surfaces are joined and secured, allowing the vascular tissues to connect.

  • Once the graft takes, the rootstock below and scion above are severed from their original plants.

• Advantages:

  • Reduces the risk of graft failure since both plants remain rooted during the process.

Summery

Grafting is an invaluable tool in agriculture and horticulture. By carefully selecting the scion and rootstock and following best practices, growers can create resilient, productive, unique trees and save valuable time and energy by shortening processes with this method. Whether for fruit production, conservation, or aesthetic purposes, grafting continues to shape the world of trees.