One of the most fascinating aspects of the plant world, for me, has been how plants propagate. Seeds, new roots sprouting from tender shoots and, most of all, attaching one plant to another and making it grow are miraculous.
Budding and grafting have always intrigued me. When I was young, I read about a tree that had more than 20 varieties of apples. While I have never created a tree with that many varieties, I have several trees with multiple varieties and have enjoyed grafting as a way to start many new plants.
Grafting and budding are forms of cloning where part of one plant is attached to another so that the plants grow together. Cloning is where individual plants are asexually propagated from a single plant and therefore are genetically identical. It is thought of as a high-tech method, but it has been practiced for thousands of years.
Cloning is the only way to make an identical plant. Luscious fruits do not naturally come just because we plant a few seeds. Most fruits and nuts do not come true from seed. The chance of getting an identical variety from apple seeds is a million to one. Therefore, virtually all commercial fruit trees, many ornamental trees and shrubs and most roses are propagated by budding or grafting.
There are several reasons why plants are grafted. The most obvious is to propagate a variety that has one or more desirable characteristics we are trying to promote. Those characteristics include flower or fruit size, color, disease or insect resistance, size control or suitability for a given soil or water needs.
Many cultivars or varieties of plants do not come true from seed. Others are difficult or impossible to reproduce from cuttings or other propagation techniques. Grafting can change a large tree from an old to a new variety. It can also provide a different root system that is better adapted to a specific soil or climate or introduce a new source of pollen into an orchard.
Grafting is also used to incorporate both male and female flowers on the same dioecious plant, such as holly, so that it bears fruit. Grafting is used to accelerate breeding programs, to test for compatibility and to determine if virus diseases are present.
The drawbacks of grafting are that it is much harder and more complicated than other types of propagation. Not all plants can be grafted. Only plants that are closely related botanically (the same genus and species) form a good graft union. The top and bottom of the plant must be compatible. Incompatible grafts may not form a union, or the union may be weak. A poor union means plants will grow poorly, break off or eventually die. Graft compatibility can only be determined by trial and error.
To understand grafting, you must understand the terms scion, rootstock and cambium. The scion is a twig or shoot that serves as the aerial portion of the graft. It is the desirable variety of whatever plant you are trying to grow.
The stock or rootstock is the rooted portion of the graft. It controls the plant size, the tolerance of poor quality soils or other growth characteristics. It is what supports the fruits, flowers or other desirable top part of the plant.
The cambium is a single layer of cells between the bark and the wood. These cells grow and divide, and it is critical that the cambium layers of the stock and scion make contact for a union to form. If the cambium layers do not touch each other, the graft will not grow.
After the graft is made, protect it from drying, disease and any movement between the stock and scion. All covering materials must stretch. If they crack, the cambium will dry out and the graft will die. Scion wood must always be right side up for the graft to take.
One rule of grafting is that the rootstock must be actively growing and the scion variety dormant. The best time to do this in our area is about the time the first buds start to come out in the spring. Grafting in the early spring allows the grafts to heal before hot weather arrives.
Collect the dormant bud wood right now and hold it until the rootstock starts to grow in the spring. Select scions or buds from vigorous growth. Watersprouts have the most vigorous vegetative buds.
Store the twigs in a cold, moist place at temperatures close to 34 degrees F in the refrigerator. Keep them in a plastic bag with moist paper towels. If they dry out, they will die.
Grafting 101
Grafting is one way horticulturists create luscious varieties of fruit. Here's an explanation of the basics at left, from top to bottom:
Cleft grafts are commonly used for large trees. Cut back half of the main limbs to where they have a diameter of 2 to 3 inches.
Split the stub of the rootstock with a special grafting tool or with a hammer and knife. Hold the split open with a chisel.
To insert the shoots (scions), insert one shoot into the cleft on each side of the stock. The thick side of the shoot should be toward the outside of the stock. Push the scion downward until the lower bud is about even with the cut surface of the stock. Lean the scions slightly to the outside to improve the chance of contact. Remove the chisel and let the cleft close. Cleft grafts are held in place by the pressure of the wood, so nails or tape are not necessary.
Withdraw the chisel and seal all the cut surfaces with grafting wax. Check the graft frequently to make certain that the wax is not cracked, peeling or dripping.
Check the grafts the next year. If more than one is growing, remove all but the most vigorous. The real test of your skill is when you finally harvest the fruits of your labor both figuratively and literally.
Have a gardening question? E-mail it to features@desnews.com, subject Larry Sagers.