Notes from Windward: #69


Bud Grafting


Starting Again

     This spring I experimented with grafting apple trees for the first time, using the whip and tongue technique to form a union between the scion wood from a few of our older apple trees to semi-standard rootstock.

     Unfortunately it didn't work out so well. There are a lot of variables involved so it is difficult to pin point exactly what went wrong. However, based on the callus cells (the tissue that the trees generate to "heal" the wound and effectively connect the two pieces of wood forever) that had started to develop but had not completely sealed the gaps between the scion wood and rootstock, my best guess is that there was insufficient contact between the two surfaces of the wood and so they dried out before the tree could finish healing the wound.

the first cut

     Fortunately, however, you have more than one shot with grafting; you just have to be patient and wait for the next appropriate opportunity, as they only come a few times a year. In our climate, August is the time for bud grafting, a technique that involves the same general principles as the whip and tongue graft but utilizes a different piece of the desired tree and different types of cuts. Bud grafting is done when the "bark slips," meaning that the bark on young growth separates easily and uniformly from the cambium layers beneath. Interestingly enough, just as the spring blossoms bloom earlier down by the river than they do up here on the plateau, the window in which the "bark slips" is delayed on the plateau as well. Hopefully, however, this time gap will not create too much of a barrier to successful budding.

bark at the slipping stage

     Earlier this spring I had planted all the root stock in the nursery. So the next step to prepare for bud grafting was to make sure I had all the right tools. A sharp knife is particularly important for making clean and exact cuts, and I wasn't satisfied with the knife I used this spring so I ordered a grafting knife online. Also, since the spring grafts may have failed in part because of an improper seal, I decided it would be worth buying budding/grafting tape. The material is quite inexpensive for a quantity that could last a life time for someone grafting on a home-scale, but it is heavy and so shipping costs about triple that of the tape itself. Luckily, because of the prominent orchard industry near here, I was able to pick some up in the hardware store.

     Once I had all the right tools, then it was time to gather the scion wood from the favorite trees. Since part of our grafting work is an attempt to diversify our apple varieties, I ventured down to the Klickitat to gather scion wood from naturalized apple trees growing along the River that we have identified over the years as worth replicating. The size of the scion wood in part depends on the size of the wood you will be grafting it to, but in general you want to gather this years growth that is about as thick as a pencil--though this is sometimes hard to find. If the scion wood is too small relative to the root stock, you run the risk of having the rootstock overwhelm and take over the graft. It is important to keep the scion wood moist between gathering it and grafting it, and so I followed the recommendation to place them in water overnight (and immediately after cutting them from the tree I placed them in gallon sized jars).

a new bud grafted into place

     For the most part, I followed the bud grafting technique I observed while at Carlton Nursery, which seems to be a variation on patch budding. First I made about a 1/4 inch long downward cut in the rootstock about 4 inches above the base of the tree, then made another cut starting about 3/4 of an inch above the start of the previous cut, joining the two cuts at the bottom, and removing the wood carved out by the two cuts. This method effectively creates a pocket into which the scion wood can fit. Then on the scion wood, I removed this years leaf from the selected bud, placed a small upward cut 1/2 an inch below the bud; then, about 1/2-3/4 inch above the bud, I cut downwards and behind the bud, meeting the initial cut to completely free the bud from the rest of the stem. I then trimmed the length of this bud to better match the dimensions of the cut in the rootstock, placed the bud in its little pocket and attached it firmly to the rootstock using grafting tape and duct tape, making sure not to cover the bud itself.

wrapped and ready to grow

     In about 10 days, I should be able to tell if the graft "took"; if either the bud or surrounding root stock look dry or are shriveling away from the edge, the graft has failed, and I try again! If the bud continues to look healthy, then the tape can be carefully removed, though maintaining some support may be helpful. The buds need to winter over before putting out new growth. Once the bud breaks, then the remaining part of the rootstock above the new bud can be removed and the new bud will become the new leader and we will have little apple trees!

Notes From Windward - Index - Vol. 69