Bench grafting and rootstock length

I’m starting my first adventure into grafting this weekend and plan to do both regular and interstem bench grafts and have 3 questions about length of rootstocks and scions.

I’m mostly interested in the interstems, but once I chop 10" off a Bud-9 rootstock to use as an interstem on a M.111 for instance, I figure I may as well graft something onto the Bud-9 as well, plus if the interstem doesn’t work I’ll still have a tree of that variety. Since I’m trying to match up widths, there is a good chance that I might wind up with some very short Bud-9 roots after taking off the piece for the interstem. So how short is too short for the rootstock to have a chance of a successful graft?

Also, since I’ll be adding the interstem and rootstock before the scion, how long is too long for the combined rootstock plus interstem - 20", 2 feet? At what point am I asking too much of a rootstock or is this not an issue? I realize doing the interstem all at once certainly makes these in particular less likely to take, so I want to make sure I give them the best chance of success.

And finally scion length. I should have plenty of scion wood so I could probably leave 6" scions on each graft, but I always see people cutting it back to 2 buds or so. Is that just to conserve scion wood and can I leave them longer or is it better to just have a small piece of scion?

I realize some of this may depend on a variety of factors, but any insight is welcome.

Zendog. My first two interstems were grafted in one season. The interstems was grafted early and the scion was added later in the same saeaon and they are doing well. These two have interstems of about 15".I read somewhere that it took this length to get the full dwarfing. As to how long can you go is purely a guess. My guess is that it is more important to get accurate and well sealed grafts than it is how long the interstem/scions are. This winter I whip grafted four interstems of dwarf pear that was between 14-16" each. All four are starting to leaf of and I expect that they will all make it. Good luck Bill.

A while back Alan explained to me about the trees vigor and how it will determine the mature tree size. My thoughts are that the less vigor the shorter the interstem. Bill

Thanks for sharing your experience Bill. When we talked about iterstems over on GW, I think you said you did them all at once, am I remembering that right?

I’m actually aiming for some trees to be quite small to try to grow as stepovers around perrenial gardens and strawberries, so I have some M.27 as well for the more vigorous types. Some I’ll try as short cordons against a fence, so I can grow several varieties on my little lot and see what I like - or at least what I can keep alive. From what I understand if I put M.27 on M.111 it may turn out closer to a straight Bud.9 but with better roots for my less than ideal soil. I was going to put the lower vigor varieties on the Bud.9/M.111 combination, so hopefully those will come in around the same as the more vigorous on M.27/M.111. I’ll keep the interstems at about 10-12 inches just to keep it consistent.

It is all a bit of an experiment.

Thanks for the correction. I went back and edited my original post above. Bill

Thanks Bill. Do you think there is an advantage to using a longer piece of scion wood or do you just do the 2-3 buds worth above the inerstem?

I’ve done a couple of interstem grafts on pears. For both grafts, both the interstem and the scion took and leafed out. The interstem (Magness) was only 4-6" long. Since I was doing it only for compatibility (with the quince rootstock) and not for dwarfing I wasn’t concerned with making it too long. I would think that making the interstem too long would hurt your chances of a 2nd take, but then, I was actually a bit surprised when my small interstem worked.

From a technique standpoint, I first grafted the scion onto the interstem, including wrapping the parafilm. Then, holding only the interstem portion (pre-cut before starting), I grafted it onto the rootstock. If you do it in the opposite order, I strongly suspect that you may not get either to take, as 2nd graft would pull the first out of alignment.

If you want stronger dwarfing, try G11, instead of B9 as the interstem. All of my G11/MM111 trees are pretty small, somewhere between M27 and B9 in size. The B9/B118 is larger than a G11 (which is bigger than B9). I haven’t seen anything in literature about this, but the trend seems consistent in my half dozen interstems from Cummins.

The advantages for me to do both grafts at the same time are.
-I don’t have to revisit this tree again for grafting purposes
-I can’t verify this but I feel like you get a faster growing and self supporting tree
-If the top graft fails you can bud graft again during the summer or wait for next spring
-I just like doing things a little different than the standard method

Other early observations of double grafts are.
-It will take a little longer for the top to grow than the inter-stem
-I like using longer w/t grafts for stability
-The tree still needs support for a couple of seasons
-All my previous grafts have been done during dormancy
-Just purchased parafilm M and i will start wrapping both sections

I have recently gone to your technique and it is a big improvement.