Digital Caliper for grafting

Does anyone else utilize a digital caliper tool to check their scion /rootstock thicknesses prior to a cut? I bought a cheap one at harbor freight and have been using it prior to cuts with my zenport style tool. It seems to make it easier to line up my unions rather than eyeballing them (also effective but takes more time.

I just check the diameter of my bud wood near where I plan to cut, and then find the exact same spot (if available) on the rootstock and try to make clean cuts.


I think so far so good… Time will tell.

5 Likes

seems like overkill to me.

But if it work for you. it works :slight_smile:

I would however mention that some scions/rootstocks have different bark thicknes.

I graft with knives instead of the zenport tool though, so im less worried about matching thickness

6 Likes

I agree I just try to aline cambium on one side only. I like sloppy looking grafts as I cut less of them off while pruning.

5 Likes

Keeping the graft surfaces clean, and keeping air and rain out of the joint is more important than perfection. (so, I just eyeball them…and the cut on rootstock and scion I get right length 90% of the time anymore on the first try before matching for a whip & tongue graft)

And a side graft can be implemented if the scion is a different size by more than a little bit.
The grafts turn out ok.

4 Likes

@disc4tw

Many years ago I kept a crescent wrench in my pocket which I used to gage the size before i cut the scion to match the rootstock. After the first year I could do it by eye.

3 Likes

I think it’s a great idea for anyone who uses splice grafts. When the diameters are the same you can line up the cambium of branch and scion on both sides and it requires only pulling tape over it. When there is a slight difference you can only line up the cambium on one side and it is difficult to hold it there as you wrap the tape which tends to push the scion to the middle so neither side touches.

I usually have a lot of scion wood to work with which would make this method particularly useful. No matter how much I study the wood, I often get the size match-up slightly wrong, so maybe it is my own deficiency of skill or talent that makes this seem like an attractive tip that would be especially useful for beginners.

I also do hundreds of grafts every year.

Incidentally, regarding your photo, I wrap the parafilm around the bud to protect it from dehydration. Growing buds push right through it. Not saying this is better, just noting that it may or may not be and that with thinly stretched parafilm at least, buds have no trouble pushing through.

6 Likes

Overthinking it

3 Likes

I’ve found in the end that the grafts I spend two minutes on have performed equally to or better than those that I over-analyzed and spent 10 minutes on. I graft “eyeballametrically” as my old boss would say. Choose a scion that looks healthy and relatively close to the stock and ensure a cambian cross. Don’t waste too much time trying to perfectly size up the scion and match both sides. Using a good sharp knife and making good cuts is more important than finding a scion with the exact diameter in my opinion.

4 Likes

do both size and health

1 Like

I use the same approach. I think I have exactly the same caliper.

I’m a relative novice. My thinking was that if I can match the sizes of the scion and rootstock, I would significantly increase the odds of success. At minimum, use of the caliper seems very helpful until you or I get enough experience to put it aside.

So, 2 years ago (my 1st attempt), I did 40 W&T bench grafts on apples with only 1-2 failures where the scion wood was so thin that it was impossible to match the rootstock width.

1 year ago I didn’t do any new grafts but this year I did ~30 apple and pear grafts, roughly 20 bench grafts and 10 on growing trees. I have seen maybe 1 failure on an outside tree.

I also did 2 persimmon grafts this year (mid March) on small potted rootstock trees. One already has 12-13" of new growth. The other looks good but has not broken bud.

Use of the caliper adds time. But especially if you are doing a small number of high-value grafts (i.e., “I REALLY need this to work!”), you’d be willing to invest some extra time to ensure success.

One caveat: Trunks and branches are generally not perfectly cylindrical. So the width measured North/South will vary from the width measured East/West. Keep track of the orientation that you measure.

Also it helps a lot to make the cuts at the same angle. A cut that is roughly 3x as long as it is wide seems right, which equates to a ~15 degree angle. Try to get the angles of the cuts the same. If the sticks are the same width and the cuts are the same angle, you can’t miss.

1 Like

I agree, but it’s not like it’s hard. I compare them, and that pretty much is all I need to do. One can find the size on the desired branch and start there Also the thing is with apples you can throw the scion at the rootstock and it will take. Now if this were to increase peach grafts, that would be saying something.
About half my grafts are cleft or bark anyway and one needs a larger rootstock. I agree with the comment of overthinking it.

1 Like

Yeah, I’m not saying it’s hard, at least not with apples. The wood seems very forgiving. But I’m more intimidated by persimmons. I have 10 small D. virginiana trees just planted as rootstock for grafting next year. I’m planning 2-3 grafts each on 3-4 varieties. I’d prefer zero failures, so I’ll do everything possible to ensure success.

My experience is that if I go just by eyeball, trying to match, say, a 7 mm section of rootstock, I might pick out a 6 or 8 mm scion. So the caliper helps me reduce the mismatch from maybe 10-15% to 3-5%. And as I’m doing this just as a hobby, it’s not that much extra time, and the caliper is not at all expensive. So it seems worth the extra effort. And if my success rate goes from 1 of 3 to 3 of 3, then my friends get more gifts!

1 Like

Anyway, it isn’t just about taking, it’s also about how much growth you get that first season. With me, rapid growth is often necessary for survival because ones that leaf out late tend to get destroyed by leaf hoppers if I’m not on top of it.

It is one thing to graft on an established tree, but if it is one that was transplanted that season or a fresh rootsock taking can be less forgiving. Even in my nursery where roots have been damaged by moving trees nearby I lose quite a few grafts compared to grafting undisturbed, vigorous trees.

2 Likes

A bit of a digression but in my time I have gone through several digital calipers but only one analog one. Solid steel, either high definition with the bubble dial or a plain caliper, it will last for the rest of your life.

1 Like

A good suggestion that can help some people. Thanks for sharing that idea.

somtimes there can be a significant difference in bark thicknes. The caliper won’t pick that up. I usualy match up the wood and then know cambium is fine.

For splice grafts putting them slightly crooked also helps. Than the cambium lines cross at a verry low angle. And usualy when wrapping you can still feel where it’s slightly crooked.

I usually graft 1-year wood onto 1-year wood, but even with 2-year wood on trees I’m grafting to I’ve never worried about bark thickness affecting contact, although it’s an interesting idea. I’m not sure if in that context it is a matter of any significance, but I will think about it. I’ve always preferred one year to one year because by the 2nd year wood gets bumpy and that interferes with matching cambium as well. Of course all my graft wood is one-year.

1 Like

I tried the zenport and calipers for a lot of graft attempts for a couple of years and found failure rate was way higher than a boxcutter for the parent and grafting knife for scion when also used with calipers. One thing I found though is that you can’t get the best cambrium match when cutting both sides at the same caliper reading. With a v cut , caliper needs to match at bottom end of v on both sides, and as they say bark thickness can still vary slightly though not by much on scion size wood…

2 Likes

Wow, I didn’t realize this would be a topic with such strong viewpoints. That isn’t a bad thing, it’s good to have a discussion! I think for me personally as a novice, it is helpful for my own confidence to have the added benefit of knowing exactly how thick my scion is for a chance to get good contact on both sides of the rootstock, and the meter is just another tool in the toolbox for adding confidence.

I will say that for those who have made hundreds or thousands of grafts, this added step likely is a waste of time and does not improve your odds. But for beginners investing in the hobby (likely with more financial impact than someone who has access to free /low cost rootstock/scions due to scale if a commercial or professional grower) having that extra help might make a big difference.

My understanding is the exact opposite of this thought process. Based on my research, as long as at least a few cells in the cambium layer match up between rootstock and scion, the graft has a good chance of taking if properly protected, proper weather etc.

3 Likes

I’m not sure what you’re saying at the end. What do you recommend? If “at least a few cells” is sufficient, is less more? Or is it still better to have more cells in contact? If a few is good, isn’t more than a few better? So then what does this imply re method?