Not long ago, while walking down Bethlehem Road in Jerusalem, I spotted a tree unlike any I had ever seen before. It had both pink and red flowers which, upon closer examination, belonged to the same crape myrtle tree. It was an example of what is known in horticultural circles as a multi-graft tree or, in jest, as a Franken-tree.
No one knows when the grafting of plants began. Initially, grafting was thought to be an extension of vegetative or clonal propagation by cuttings. Just as softwood (flexible) or hardwood (woody) cuttings, detached from shoots or stems and placed directly into the ground at the proper time of the year, will strike roots and grow into new plants, it was thought that grafting involved a similar process. The only difference was that, in grafting, the detached cutting from one plant would supposedly “take root” in the stem or the trunk of another.
Today, we know that the cambium, or actively growing, layer of cells just below the bark is responsible for a successful tree graft. Where the cambium of the recipient stem unites with the cambium of the bud or stem grafted into it, the graft is successful and the two plants now grow as one.
Grafting trees for commercial purposes is a relatively recent phenomenon that began in the 19th century with dwarfing rootstocks. Note: A grafted fruit tree consists of a rootstock, grown from a cutting or a seed, upon which a scion variety or cloned plant material from the fruit or nut tree of your choice is grafted. There were dwarfing apple rootstocks, long planted in Europe, which in the late 1800s began to be planted commercially with popular apple varieties grafted on them. The appeal of dwarfing rootstocks is obvious since they minimize the labor involved in harvesting fruit. Today, many of the fruit trees found in nurseries are labeled “dwarf” or “semi-dwarf.” These designations are somewhat misleading since a dwarf may grow to the same size as a semi-dwarf. Generally speaking, however, a dwarf tree will grow no taller than 10 feet, and a semi-dwarf no taller than 15 feet. However, you can keep most fruit trees of any description at a height of 8-12 feet and still harvest good-sized crops.
When shopping for fruit trees, you will often encounter “Fruit Salad” multi-graft specimens that share genus affinity. Trees of the same genus are generally compatible when it comes to grafting. Thus, you can have a lemon, grapefruit, orange, and mandarin growing on the same tree since all belong to the Citrus genus. Similarly, you can graft a plum, peach, nectarine, apricot, almond, and cherry onto the same tree since all belong to the Prunus or stone fruit genus.
Where multi-graft Prunus trees are concerned, the most world-famous specimens are the work of Sam Van Aken, an art professor at Syracuse University. Van Aken grew up on a farm and was not a stranger to growing fruit trees. He conceived of a project that would combine art with horticulture and grafted 40 different varieties of the six Prunus fruits mentioned above onto a single tree. He has produced more than a dozen such trees to date that are both on public display and in private gardens. Each spring, the trees dazzle brilliantly with an extended show of red, pink, and white blossoms. From July to October, the trees are resplendent in the gold, orange, red, and purple colors of the various ripening fruits
If you decide to grow a fruit salad tree — whether purchased or grafted personally — you will need to be aware of the relative vigor of the multiple varieties involved. Greg Alder (gregalder.com) recommends that when the tree is planted or grafted, the fastest-growing or most vigorous variety should face north and the least vigorous variety face south. The reason for this is that a southern exposure promotes more growth than a northern one. If you plant the more vigorous variety facing south, it could grow explosively and shade the weaker-growing variety or varieties; better to be safe and orient the most vigorous variety to the north.
When I visited Ronni Kern — who leads the West LA chapter of the California Rare Fruit Growers — in Santa Monica, I was impressed with her multi-graft fruit trees. She told me her fig tree story as follows: “I have about eight varieties on what was originally a Black Mission fig that reached the second floor of my house. Because of black fig fly, whose larvae devoured the fruit, I cut it down to my knees to make it easier to protect with polyester netting. Since that radical pruning caused it to produce many low branches, I grafted it over to Bourjasotte Grise (delectable taste, juicy, doesn’t split), Black Madeira (mix of flavors including maple syrup and honey), Janice Kadota (nearly seedless, sweet, greenish-yellow fruit, long-lived variety), Smith (large yellow fruit, red flesh, sweet berry-like flavor), Victoria (berry flavor, jam-like texture), Raspberry Tart (berry flavor and raspberry red flesh), and a couple of others I can’t recall. The virtue of grafting is, of course, the opportunity to cram many varieties into a small area. It’s also a chance to taste varieties and see if you want to occupy more space with them. Using healthy scions is key, as well as sterilizing tools. Figs almost invariably carry mosaic virus, but my trees don’t seem to mind it.”
On her Anna apple tree, Kern grafted Ein Shemer, Dorsett Golden, and Red Calypso. Finally, she has top-grafted four different varieties onto her persimmon trees, including Coffeecake. This is a non-astringent, low tannin variety that does not need softening to turn sweet, but may be eaten while still firm. It has a spicy, cinnamon flavor reminiscent of coffee cake. When it comes to persimmons, “I am a little obsessed,” Kern confides. “They are such pretty trees, and the fruit is so yummy.” If you wish to learn how to graft fruit trees, get in touch with your local chapter of the California Rare Fruit Growers (crfg.com). When you get to the site, click “chapters” at the top of the home page to find the one nearest you. Most chapters have regular meetings where you can learn the grafting craft and exchange scion wood for grafting purposes.
Greg Alder has had great success with multi-graft avocado trees. In one case, he grafted several different varieties onto a volunteer avocado that sprouted in his mother’s compost pile. Two of these were Hass and Fuerte, California’s most widely grown avocados. These varieties enhance the yield of each other since Hass is an “A” type (female flower parts open in the morning, male flower parts in the afternoon) and Fuerte is a “B” type (male parts open in the morning, female parts in the afternoon). Although a single avocado tree will bear fruit, it bears more heavily in the presence of a compatible variety — a “B” it’s and “A” and an “A” if it’s a “B.”
California native of the Week: Calico monkey flower (Mimulus/Diplacus pictus) is outstandingly distinct from our more familiar native monkey flowers (no slouches in their own right) that are annual or perennial, bloom in yellow, orange, or red, and crop up on freeway embankments or where there has been ecological disturbance. Calico monkey flower also grows in disturbed areas, especially in woodland and forest locales, often on bare or rocky soil. Yet calico monkey flower is strictly an annual wildflower and features a floral personality all its own. Growing to a height of 15 inches, its five-petaled flowers ore intricately sketched upon with a maroon pattern complemented by a tubular maroon throat. This is an endangered species whose seeds are available (100 seeds for around $10) at Etsy.com