Side Grafting Side grafting is the best strategy for top-working stone fruit like plums, peaches, apricots, and cherries. Timing is crucial for this method of top-working: the scion is dormant, but the understock is starting to break bud and there is a flow of nutrients from the roots taking place. This movement of nutrients to the periphery of the understock helps speed the development of a callus union between the scion and the understock. Once the scion is pushing strong growth the section of the understock beyond the union with scion is removed.
Click here here to see an excellent set of illustrated instructions for the side graft that Bob Purvis of Homedale, Idaho, published in the North American Fruit Explorers publication.
In the article mentioned above, Bob notes that he learned the side grafting technique from Dan Whitney of Whitney Grafting, a grafting business involved in topworking huge blocks of fruit and nut trees for commercial growers throughout the US.
Whitney Grafting has used a Face Book page to communicate with customers since 2017. During that time they have shared some excellent photos and videos of various grafting techniques employed by their grafting team. Among these are some excellent photos of side grafting (mostly cherries, but also apples and pears). A link to their Face Book page is here.
Below is an annotated guide to the dates where there are photos of side grafts. In some cases the topworking technique is used to replace side limbs with a different variety and in other cases the entire tree is being replaced above the side graft.
1. April 13, 2023 Video titled "Now we are starting . . . " Note that they are using 3 or 4 bud scions (vs. 2 bud scions more commonly use for bark grafting, cleft grafting, and whip and tongue grafting). 2. March 3, 2023 Photo of side graft of cherries. 3. April 21, 2022 "The cherry grafts . . . " Example of side grafts on very large limbs. 4. March 29, 2022 "I'll be glad when we finish these cherries." Shows side graft on understock that is breaking bud. Side grafting is always done on vigorously growing undestock (a critical success factor) in the photos and videos on the Whitney Grafting FB. 5. March 23, 2022 Side grafted cherries. 6. May 2, 2019 To prepare for side grafting cherries, the large side branches were removed. This stimulated lots of new growth (smaller branches) that could be topeworked using side grafts. 7. March 26, 2019 This FB entry shows an example where the side graft took, but the host limb was not cut back and continued to grow and compete with the side graft. The normal practice is that the experience grafting crew from Whitney Grafting comes in and places the grafts in the spring and the customer comes along in the summer and removes the host understock from beyond the location of the side graft (which was not done in this case). 8. April 10, 2018 Excellent photo of the "J cut" (not equal on both sides) on a horizontal limb. The J cut is shown in diagram the Garner text, but easier to see the placement of the scion into the J cut in this photo sequence (can see where the cambium of the scion intersects with the cambium of the understock). Also you can see that the J cut is not merely cutting back the bark, but actually going a little ways into the heartwood of the understock, which actually acts to hold the scion firmly in place. 9. May 8, 2017 "Forelle pears that will be Bartlett now in Salem Oregon" The other entries above have related to the use of side grafts to replace limbs in topworking existing trees (purpose: to change variety). In this FB entry the purpose is to change the whole tree from the point of side graft up. These are young trees with a stump diameter of only 3 to 4 inches. The limbs above the location of the side graft have been cut back, but there will be a draw of nutrients upward beyond the side graft that will help create the callused union of scion to understock. After the side graft shows strong growth the understock is removed above the site of the graft (later in the summer). 10. April 14, 2017 Example of side grafts on 2 1/2 to 3 inch understock. Note the presence of a 3 to 4 inch stub left from removal of understock during the previous summer. It is likely that the stub will be removed during the current (2017) growing season to promote a full healing over of the union of scion to understock. Also note the use of bamboo poles to support the vigorous growth of the previous year (2016).
[Question: But why fuss with side grafts? There is a thought that crosses one's mind when comparing side grafts with cleft grafts and bark grafts, both of which are much easier to execute than a side graft because you don't have the understock to contend with that lies beyond the point of the union of understock to the scion. Why fuss with leaving the understock around until the understock-scion union is made? If you are grafting confers the answer is easy - you can't get a cleft graft or bark graft to work - you have to use a side graft technique for success. The answer to why use side grafts (which retain the understock) is less easy to see with temperate zone fruit trees like cherries and other stone fruit, pears, and apples because in most cases bark grafts and cleft grafts work just fine. I suggested one reason above when I spoke of the understock above the side graft as pulling nutrients out to the periphery (hence, by the site of the union). Although that is true, the other (and maybe more important) reason may be to deal with too much flow of nutrients as experienced with bark grafts in Michigan where you have to cut slits (called "relief cuts") in the bark/cambium layer below the graft to drain excess fluid. This is also the explanation of why "nurse limbs/feeder limbs" are left on topworked trees - they achieve the same end as the relief cuts. For more on this take a look at my annotations for some of the Whitney Grafting FB entries on the page for bark grafting on this website.
[ Brief comment about terms: Throughout this page on this website I am using the term "side graft" to speak of what is designated the "oblique side graft" in The Grafter's Handbook by R.J. Garner. Technically there are two difference in the execution of the side graft vs. the oblique side graft. One is the angle of the scion to the understock, with the oblique side graft being at a more oblique from the understock than then regular side graft which tends to be aligned with the direction of the understock. The other difference is in the preparation of the scion, with the scion for the side graft being tapered on only one side and scion for the oblique side graft being tapered on two side (similar to a scion prepared for a cleft graft). Throughout the remained of this section below when I use the word side graft, I actually am referring to what Garner calls a oblique side graft (sorry for the imprecision R.J. - just easier to say side graft than oblique side graft). ]
[ More comments about side grafting: In other propagation books (besides The Grafter's Handbook focused mostly on fruit tree propagation) side grafting receives much more attention with descriptions of several other variations of technique (e.g., side-stub, side-tongue, side-veneer) and application (e.g., confers, tropical fruit). Some helpful references include Hartmann and Kester's Plant Propagation: Principle's and Practices, The Bench Grafter's Handbook: Principles and Practices by Brian E. Humphrey, and The Manual of Plant Grafting: Practical Techniques for Ornamentals, Vegetables, and Fruit by Peter T. MacDonald. ]