Saratoga News Grafting allows strong roots and other desirable qualities Tony Tomeo Those who have already planted their bare-root fruit trees may have noticed that almost all of them have a distinctive bend in the trunk a few inches above the root system. Roses also exhibit this bend where the canes branch from the single vertical stem that rises from the roots. This is where the plant was grafted. Grafting is the union between plants with desirable roots and plants with desirable fruit, flowers, foliage or form. In some cases, grafting is done to propagate cultivars of species that do not root well from cuttings. Norway maples, for example, grow well from seed, but not from cutting. Seedling trees, which are subject to genetic variability, are used to provide the root system, or understock for grafted trees. The stem, or scion, used to provide the genetic material from which the actual tree grows may be taken from an individual tree selected for its genetic superiority. All trees grown from this superior tree will be genetically identical clones. Clones selected and propagated by asexual means are cultivars. "Schwedleri" is a cultivar of Norway maple widely planted around the Santa Clara Valley. All grafted trees are identical, but trees grown from seed from these same trees would be noticeably different. Citrus and other fruit trees may be grafted onto dwarfing rootstock to keep the trees manageable. The root systems of the understock restrict growth of the mature plants that depend on them. Dwarf citrus are just the right size for the average yard, and the fruit is not so far out of reach or produced in overwhelming quantities. Standard citrus are grafted onto invigoriating rootstock, but few suburbanites want a 20-foot orange tree in the yard! Some plants, such as roses, are grafted onto roots that are better suited to the soil in our area. Roses will grow if rooted directly from cutting; but the resulting root system will be inferior in quality to that normally used for understock. Sometimes grafting can be used to add another scion to existing fruit trees so that individual trees produce different varieties of the same fruit. Grafting can also be done to replace unwanted fruit trees with more appealing varieties. It is easy enough to be performed by the gardening enthusiast; but I recommend studying the process somewhat before trying it. The scion--the piece to be grafted onto the understock--should be about as big around as a pencil and should contain at least two healthy dormant buds. Scions may only be grafted to plants of the same genus. This can still be very interesting, because plums, nectarines, apricots and peaches are all related and can be grafted together. Likewise, citrus are compatible with each other. The scion needs to be cut at the lower end on both sides, forming a long, drawn-out wedge. A stem on the understock must be selected for grafting and cut straight across leaving a stub at least a few inches long. The stem must be at least as big as the scion and may be up to two inches in diameter. This stem must then be sliced cleanly down the middle, deep enough for the cut end of the scion to fit within. When the scion is fitted into the slice, it is imperative that the cambium--the layer of vascular tissue just below the bark--fits tightly together with that of the understock. It is then best to tie the stem closed with a tight rubber band, so that it is held under tension. Electrical tape is suitable for larger stems. I always recommend sealing the union with wax to prevent desiccation. This is easily done with a Q-tip dipped into the pool of wax which forms in a large pillar candle. Grafts are not always successful, so you may want to try several on the same understock to improve the likelihood of at least one surviving. Excessive scions may always be pruned off later. Success will be indicated by shoot growth on the scion in the spring. When this occurs, break flowers off the scion, leaving only vegetative leaf growth. As the scion expands, wax and wrappings will fall off. Premature removal of wrapping will likely damage the graft, so be patient. If you have more than one cultivar on a single understock, it will be necessary to prune in a manner favoring the slower weaker cultivars as the plants mature. For example, trees producing peaches and nectarines will favor the peaches, and the nectarine scion would likely be shaded out if not given special accommodation. Shrub of the Week: Witch Hazel I always thought witch hazel, Hamamelis intermedia, was excellent for fall color, ranging from clear yellow, or coppery orange to bright red, depending on the cultivar. It is also great for its winter bloom cycle which comes as early as December and as late as March. The flowers are clusters of small tassel-like florets on bare stems, ranging in color from sulfur yellow, to orange and coppery red. Some cultivars produce fragrant flowers. Stems of witch hazel may be cut and brought in as a cut flower. The shrubs flare out from the base, eventually reaching 15 feet in height. They express an unrefined character and are well suited to informal gardens. Witch hazel should never be sheared or in any way deprived of its natural form. It will grow in full sun, but is better adapted to understory growth in the company of larger trees and buildings. It prefers at least some organic matter in the soil and moderate irrigation. Witch hazel has become much more available in many of the better stocked nurseries in our area. You may want to shop for it in bloom to make more accurate choices of color. However, because fall color is so intense, read the label to take both seasons into consideration. Tony Tomeo can be reached at 358-2574. [ Back to Contents Page | Saratoga News Home Page | Archives ] This article appeared in the Saratoga News, January 13, 1999. ©1999 Metro Publishing, Inc. All rights reserved.