Peach graft logging spring 2018


Its possible to make a stab at estimating the number of good callous hours from the Weather Underground plots. Here are my current plots from my backyard for the most recent week for example:

The sun intensity is the lowest line, the yellow one. You can see that from about midnight to 5AM today (the 14th) I had near perfect callous temps, and it was also nearly perfect for about 12 hours after I did the grafts on Thursday. I also had around 8 hours of bad over-heating on Friday. The goal is to maximize the hours of optimal ~70F on the grafts while minimizing the overheating hours. The hard question is which is most important - grafting at colder temps will minimize the overheating but will also give many fewer good hours. The night-time hours in particular are really good on warmer days, I have accumulated many good hours in the last two days at night.

A long time ago I found a picture of peach callous rates at different temperatures, but I can’t find that graph now. It would be good to have that data; my recollection was there was no callousing below about 50F and above about 80F; I don’t remember how quickly it tapered off though.

One other factor I am going to try to measure his how much the foil helps. I was surprised at how consistent the temps I measured were and I didn’t notice a lot of different of foil vs not. The exposed trunk would heat up the grafts even if they were under foil. It suggests that painting the whole trunk white or covering it all with foil could be a good idea in weather that is too sunny. Or, just block the sun with a barrier of some sort.


Great idea! You’ve inspired me to start a grafting notebook and to pay more attention to the conditions of the day and following days during the healing process. Also a place to note ideas, inspirations, and insights I’m always having when I’m doing the grafts. It seems that every year I have to relearn small details of grafting my fruit trees this would be a great way to review last years lessons learned.



From my observations, I think peach trees will callus above 80F. We’ve had extended periods of sunny 90F temps at times here and I see pruning wounds callusing. I do a lot of fall budding and temps above 90 will kill the buds, but anything near 90 or slightly below will callus and bring widespread success. I’ve done some fairly decent budding numbers the last 4 years, so I think it’s a fair sample.

I plan to graft a few peaches at different times this spring, and will offer input along with everyone else. Right now we are supposed to be sub freezing for the next two nights, so definitely not grafting weather here.


Scott i thought about what your doing and came up with this for my personal grafting log.
So I came up with this guide line.
Grafting Log Entry Information

SUN CONDITIONS: (bright overcast sun and clouds)

LOCATION OF GRAFT ON THE TREE: (a picture helps)

log for next 2 weeks

FALURE with notes of autopsy

Can you think of any thing else to add/or delet?


Maybe the materials used? Parafilm, wax, electrical tape, vinyl tape, etc.


Glad I shared this your right.


Also the diameter of the scion and rootstock. Could probably be added info into the condition section


Added that also. Shall I update the data sheet and post it?


Calokie, that looks like a very complete sheet! Right now I am more interested in logging hours at different temperatures for peach grafts, you probably don’t normally need that fine-grained degree of data though.

I was out logging my grafts today since I didn’t get around to writing down what I put where (I both write on the tree and then later in my spreadsheet) and I noticed many peach grafts from five days ago are already pushing a bit. I had heard you don’t need more than a couple days of good temps, and looking at my temperature history I got 2.5 days (60 hours) of nearly solid 60-80F temps before it dropped to more like 50F on average. Taking the over-heating into account, I lost about 8 + 8 = 16 hours of that 60 due to over-heating in the sun on two days so thats a total of around 45 hours of good callous temps. I may have added a few more good hours because it was sunny a bit in the last few days around 50F. The sun intensity was much lower and I didn’t measure the graft temperature directly, I will try to do that in this cool spell to see how much warming I am getting to see if I am getting any good callous hours.

Here is picture of one, they are just barely pushing but based on past experience thats a very good sign:

As I work more on this I’m more and more thinking about measuring peach callous hours, the number of hours where the graft area is from 60-80F. Maybe you need something like 40-50 peach callous hours and you are good, provided they happen without too many overheating hours in between. It will be interesting to see if later grafts are failing due to too much overheating, or from the tree being at a later stage of growth. Its probably some of both.


I checked on my grafts today and noticed 2 grafts about to push bud. They didn’t break through the parafilm yet. But very close. I pretty much had the same temps as you did so I’m very hopeful that they are actually taking. Very excited! They were very dormant when I grafted. Will post pictures as soon as I see something come out.


Scott what is the cream colored stuff that has bubbles on your graft? Is it Elmer"
s wood glue?


Its Doc Farwell’s grafting compound … it is something like latex paint with more latex in it (more rubbery). I like to use it when doing lots of grafts, its faster than wrapping with parafilm. Wax is sometimes used for a similar purpose but you need to heat up the wax.


Today it was sunny much of the day and I checked the temps around 5PM … air temp was around 60F and the grafts were averaging 65-70F. The air temp was in a warming trend later today so I expect that is why the difference was not greater. In any case on a mostly sunny day with high 55-60F it is clear some good callous temps are happening. This only gives ~8 hours in a day though, and I was getting ~16 hours of good temps per day when it was too warm during the day but good temps at night. Also, any period of the day when the grafts are blocked they may be too cool. Overall though, sunny days with highs in the upper 50’s to 60’s should be good callous days. 50’s highs with no sun I don’t think will be very good, and thats probably when I had my past early failures in colder weather. We have a lot of that in the spring.

Some of the grafts lost their aluminum foil in the wind but they were not appreciably cooler, less than 5 degrees difference. The live wood has enough water in it so the conductivity of the heat from the exposed parts of the stock is going to even things out it looks like. Aluminum foil may help keep grafts from drying out since its another layer of wrap, and the direct exposure of the wood to sun may also be bad in some other way (?), but I don’t think the cooling effect alone is worth it.


That’s a lot of fields. I capture less and it is still a bit of trouble. I use a recorder (my phone) in the field and each night transcribe it into a spreadsheet. One of the most important parts for me is the location, as tags have a way of coming off or becoming unreadable. When that happens, I can go through the grafts on a particular tree and figure out what something is likely to be based on height, vertical angle, and orientation (NNE, SW, etc).

Here’s an example:

That Y/N column (J) is to indicate if the host plant is already established, or if it is a new rootstock.

Columns E/F are for scion size (3B ML= 3 buds, medium large diameter).

Column D indicates source of the scionwood (intentionally blank in screenshot)


Some more interesting data: its 48F and mostly cloudy outside now, but without sun the trees are showing around 35F at the grafts! That is surprising, I was expecting something around the air temp. I assume the ground is cold and that is conducting into the tree via the roots - ?

That is a pretty significant difference in terms of temperature, and if it generally holds that in spring there is a 10F or so lowering of the temp when not sunny it can have a major influence on callous rates. It also may be that at night-time a similar effect holds so 10 degrees also needs to be subtracted from the night temperature to calculate callous hours.

Overall thats a 20-25F difference between sunny (+10-15) and cloudy (-10) as far as graft temperatures go - I can’t believe how big that number is.


Today it was windy and with the little rain, I suspect that may have been the effect of evaporative cooling.


That would be pretty weird physics. I’d think it’s more likely that your infrared thermometer is reading something other than the graft tissue, like the background soil. Not much water movement yet in the tree, esp in the graft area, and any water moving would have a long time to reach air temperature.

I’m not at all surprised that tissues warm up in the sun by 10-15F.


Hmm. It could have been evaporative cooling but there was no rain all afternoon where I work. I was not home so there could have been a spot wetting though.

@fruitnut, water doesn’t need to move for heat to transfer, there is also conduction. Its why you let something sit after microwaving it, the hotter outside can conduct heat through the liquid in the food to heat up the middle - you don’t need to stir it. The question is how big that effect is.

It does feel like too big of a difference for just conduction so I am starting to wonder if it didn’t get wetted. Hopefully there will be a calm cloudy day so I can do another measurement or two. I am 100% confident in the heat gun reading, it is measuring a very narrow spot and I did many repetitions to confirm the number. Occasionally it throws out a bad reading but in a series of readings it has never mis-read a surface temperature.

If it is evaporative cooling that is one more variable in computing callous hours - rain often comes with wind in the spring and that could give this 10F cooling on such days.


Water is poor in thermal conducting


Yes but its all relative … water is 25 times better than air. Given the small trunk cross-section though it would probably need to be more like 250 x greater to explain the results I was getting.