Tiny scions

There is a trade-off between how thick the scion is and how conducive it is to grafting. If thicker was always better we’d be grabbing 1" diameter scions if we could. But there is a diminished return, the thicker wood is more mature and doesn’t seem to callous as well based on my experience. The thing that compensates for that is thicker wood can on the other hand be more vigorous, which is better for success. A thin but vigorous scion is the best.

Re: the hose analogy, if that was true professional nurserymen would not be bud grafting nearly all of their fruit trees … with bud grafting there is only one tiny bud, not even a thin hose.


I’m not so sure, though. I think it’s more likely that budding is a way to get your grafted variety to use the full “hose” diameter of the rootstock, as once it calluses it’s just like any other bud on that trunk/stem. If you graft a thin stick to a thick rootstock, then the sap flowing from the rootstock to the bud on scion has to pass through the bottleneck of the thin scion along the way.

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Although at first glance this seems plausible and likely. I think however the reasoning is flawed here.

While grafting. You cut both types of vascular tissue (phloem and xylem). And thus sticking to your hose analogy, the hose is cut.

By grafting we’re trying to reconnect the “hose”

However, reconnecting existing xylem is not possible. When the graft heals, existing phloem is reconnected (i think, can’t find the source for where i remember reading this) and vascular cambium starts making new xylem and phloem.

Here the hose analogy brakes down. Since when reconnecting a hose, the middle part is conductive again, however with grafting the middle part (xylem) can’t be reconnected. But you could compare it to a kink in the hose.

The graft union (kink in the hose) is the bottleneck. The thickness of the scion (hose) after the kink does not affect throughput to any reasonable degree.

Think about it. If also seen 1" thick branches grow from a single small bud in 1 growing season. There wasn’t even a “hose” there to begin with. But still it could grow to 1" in a season.

If we’re guessing. I think the cambium thickness probably plays more of a role. In older wood it’s often a few cells thick. And younger but mature wood it can be a few times thicker. Thus more cambium thickness = faster graft healing and faster vascular tissue growth = faster repairing of “the hose” and growing a thicker “hose”.


It first has to pass through the “bottleneck” of the graft union. And if you think about it, as soon as the bud starts growing a shoot, that shoot isn’t immediately 1" thick. Should that not be a larger “bottleneck” than the scion the new shoot is attached to?

I think a “hose” is a bad analogy for what happens in a tree. A hose is a reasonable analogy for the xylem, since that is a collection of thousands to millions of tiny tubes filled with water. However at that scale Capillary action dominates. And the tubes don’t “act like” we are used to from a macroscopic scale “hose”

Next to that, in tree’s there are multiple separate “transport routes” for example the xylem mainly transports water (and dissolved substances) upwards. However there is also phloem, which can transport both ways. And transports most of the sugar. The phloem acts more like interconnected “pumps” than a hose.

anyway, if not seen a significant difference between thin scions and thick scions in growth. And now a few years later some of my thickest stems where from some tiny scions. However last few years i mainly switched to chip budding so, that anecdote is from a few years of growth.

The graft connects and healing is accomplished in spring giving the rest of the season to benefit from the larger diameter of not only the scion but the diameter of the shoot it is grafted to. You have to realize that I’m grafting to water sprouts and a thicker water sprout obviously is more vegetatively vigorous than a thinner one. The further down you graft on the water sprout the less energy will be drawn to buds below the graft on that water sprout. Think of a water sprout as a small individual and immature tree whose roots begin with the tree it is attached to.

As far as diminishing returns, the problem for excessively large scions is not about vigor of growth after healing, it is that they never take at all. There is a point where the original stress of water loss kills the scion, apparently, and an over thick piece of wood dries out quicker than a thinner one or needs a few more days to heal and dries and dies before it is accomplished. Diminishing returns probably isn’t the right term for that, the drop-off is sudden. . .

I am theorizing after years of observation of the superiority of thicker scions to very thin ones when using splice grafts. Unless you are doing the same, that is, drawing from a great deal of anecdotal comparison, disputing the why isn’t very important because we cannot really know why. If you’ve observed that thin scions have grown as vigorously as thick ones when grafting to vigorous shoots then you have a basis for questioning my observations- my anecdotes or random observations are not science.


Thinking about this, I wonder how much the difference you’re observing has to do with the specific scion and how much it has to do with the variety. Like, how much does it have to do with the thickness of the scion and how much does it have to do with the vigor of the variety, with vigorous varieties tending to produce thicker scionwood and more vigorous grafts, but not necessarily more vigorous grafts because thicker scionwood?

Or would we see these differences even with scions of different thicknesses collected from the same tree? Some of the wood in a given tree will be prepared to grow more vigorously (like watershoots) while other wood less, so does that difference tend to show up in the thickness of scion wood, and that tendency for vigorous growth (or not) tends to carry over to the early growth of the graft?

This is just my curiosity and I agree that the observation itself is of greater practical importance.

I’m comparing same varieties, same days, same locations- sometimes grafted to the same trees with equal exposure to light.

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I have done that in Michigan with and even shorter season. Well maybe about the same. I agree though bigger pieces are a definite plus for me. I need all the help I can get and big pieces give time for even poorly aligned pieces to take.
If better aligned eight feet of growth can occur. Quite amazing.
In general I’m trying to make a new scaffold of the graft. And this growth really helps get it done quickly.

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I go long on those skinny scions. I’ve had some which I grafted 3 buds unsuccessfully but the 5 or 6 bud length seems to have enough energy and moisture to make it through.

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