Last year after several years of failures on grape grafting where I had batted 0 out of multiple efforts I read a posting from @jostabes, in Germany titled “Holz auf grün propfen”.
So I consulted Jack as to the details involved in his method, after several exchanges I learned he actually has two proven methods: I refer to them as
Holz auf Holz: using dormant scions, on new growth, and
Grün auf Grun: using green scions on green growth.
So after several consultations when I felt I understood his two methods on the 5-7 of July when my vines had Bebe sized fruit clusters, and my temps were consistently above 70F, I performed 15 dormant scion grafts and 5 grün scion grafts.
Today I updated my takes and again thank Jack for tutoring me on his methods.
I have the following successes:
Holz auf Holz: 5 out of 15
Grün if grün: 3 out of 5
So I must say I am very happy with these two methods
No I had always done below graft slices to prevent flooding, I think it was just lack of vigor for earlier time in season or perhaps nighttemps too cold. Any way his methods seem pretty fail proof. His take % is much better perhaps because he completely beheads a vine before bud break and uses the new shoots whereas, I did not want to completely cut the rootstock off a foot above ground since I desire to get this year’s harvest. With more vines I would follow his process completely.
Or this is how Jack described it to Me. You can adjust schedule to meet his minimum temp prescribed:
“Hello Dennis,
Sometime go I read an article about a grape grafting method called “Holz auf grün propfen”, meaning grafting scions of last year’s growth (wood) onto branches grown this year (green). According the article the success rate is very high and the mechanical strenght of the grafts would be better then those of bud grafts. So you keep your scions in the refrigerator until the new shoots are strong enough to be grafted. The best period is after blooming of the grapes (end of may until end of june). So I thought to give it a try. I wanted to change a Frankenthaler (greenhouse grape) to Suffolk Red. The Frankenthaler is at least 30 years old. Last year (may 2021), I cut the whole “rootstock” about 20 to 30 cm above the ground. During the growing season (2021), I kept 5 new strong branches to be grafted this year. I kept the scions (Suffolk Red) in the refrigerator (cut in february, wrapped in moist cococoir) until 10 th june this year (few weeks ago). To solve the problem of bleeding I made some cuts (nothes) in the part of the rootstock branches below the grafts. So there is no excessive pressure at the union (wait until bleeding stops after cutting the branch, otherwise, make some cuts more). On the 10 th june I grafted the desired variety using different methods (cleft, modified cleft, whip & tongue (most of them)). I also made some bud grafts on the 1 year old branches. As you can see on the pictures below, the grafts look very promising. But to be sure, I have to wait a few more weeks.
Jack’s response to my inquiry:
The grafts were done at 10th of june last year. I think that the blooming has just ended. But in the article, it was emphasized we have a “window” to do the grafts. Too soon, the new shoots will be to week/soft to graft on, and too late, the successfull grafts will not have time to harden off to survive the winter. Another reason why june is a good period to graft this way is that the temperature is sufficient high. To successfully graft grapes, temps of 20°C (68F) or higher are necessary. The high rate of success I had last year is mainly because the grafted grape is standing in a greenhouse, so temps were well above 20 °C. This summer I’m going to graft several winegrapes outside to change the variety, so fingers crossed temperatures will be high enough. I’ve cut the complete heads, leaving only the trunks. So I hope I get some strong shoots on the trunk to graft on. To answer your question, I did also some budgrafts last year on last years wood (not on new years). Although they all started to push green buds, none of them (5X) survived. The reason for this is probably that I didn’t cut the stems above the budgrafts (I grafted the other W&T’s on the same branches …). And there is something like apical dominance, causing a push off of the lower grafted buds.
Jack”
