Hot Callus Pipe DIY


ALSO excellent for quick-healing of Asian pear scion which was starting to push buds. Thanks Dax!


Update. After my trip, there is great callusing on all my grafts. A few popped buds, but many are still dormant. I’m definitely sold on both the Zenport grafting tool and the hot callus pipe.


Thats some very fast growth there!
Of the persimmons I did only one is showing growth so far.


Amazing. Peel any growth or snip off from the rootstock Gary & be sure to acclimate any live growth from the scion(s) under a shop light or shade cloth outdoors till it becomes green and then it’ll be good for sun. I acclimated a graft for 7-days under a shop light LED and it was pretty green at that point. I took it directly to full sun and it’s been fine.

One thing I noticed is a batch of persimmons I did (@ramv & others) with real skinny caliper and light on roots is really taking a long time to push bud growth on the scion while another batch of persimmons from another nursery with more than twice the caliper and roots all came off the pipe and are pushing growth. So extra reserves really helps.



which tool are you using?


This tool which is sold everywhere from eBay to Amazon to Aliexpress to Alibaba with this modification using a round rasp. The modification is for cutting thicker scions that would otherwise be crushed without the extra rounded out notch.


There’s a long thread about this tool should you care to read, Derek… however, I’ve summarized it for you in one photograph. There’s a rosy pink model and then there’s this light tan. The rosy red is a bit better built but both work perfectly fine.

Here’s where to buy extra blades which you should have on hand:

Replacement Blades Aliexpress Seller



Black walnut

The modification to my tool and then I painted it.

Pictures from other members:







I also searched and didn’t find it. But I found this one, which might be even better suited than the originally proposed device:

It says “with thermostat, 5-25° C above ambient temperature”.

I bought it, but I don’t know when I’ll get around to use it.


Has anyone tried using this procedure to graft citrus in the winter?


@Barkslip, are you thinking of making any changes this year based on your experience last year? Any lessons learned to share? I’m curious if you think you had any issues with the temps being too hot, etc. I’m considering it for a bunch of persimmon and pecan grafting this year.

Also, you mentioned some of the persimmon rootstocks being small and I was wondering if they were from the Missouri seedling programs. I will be getting mine from them this year and was wondering if most will be big enough to graft with right away or if they’ll need some growing out before grafting.



Yeahhhh, probably. I think 3 of 4 times Missouri’s persimmon rootstocks averaged 1/8" and within a bundle of 25 you might get 5 or 6 that are up to 3/16ths. I’ve learned that Kansas is another state (nursery) that ships outside their state. Their online ordering starts December 2nd. I got 300 persimmons from them last year after calling to find out how many in a bundle of 25 might be 3/16ths and what they had last year was like 8 or 10. I’m going to buy some seedlings from them on Dec. 2nd since I missed MO. this year.

There is nothing I would change, no. I texted the guy that built it before coming on here and asked now that he’s been using it (3-4, 3-years) if he’s seen significant increases in takes from potted and well rooted stock vs. wrapping bareroot seedlings in wet paper towels and bagging them and he said he’s gotten better takes from bareroot so I leave that for you.

Best regards,



Thanks Dax. Great info as always. A bummer the MO rootstocks may be small, but you can’t beat the price! I may pick up a few from KY as well just to be sure I have enough good ones to graft this year.

I’ll definitely build a callus pipe based on these plans. Only problem I see so far is finding a 2" foam insulation pipe. Everything I see at the big box home improvement stores is smaller, so I’m going to try some plumbing supply places. If that doesn’t pan out, I might build a long box out of 1x3 furring strips and drill holes to put the grafts into, possibly using small bits of foam to stuff into the holes to seal gaps.


I think the only thing I could buy (local rural hardware) was 1.5 foam. It works perfect. Don’t change it up so you aren’t using foam.



if you can’t find pipe foam, i think a pool noodle would work also… usually they have them at Walmart in the summer


^^^ excellent suggestion


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Last year I did trial test hot callus pipe and it worked for the callusing perfect, but unfortunately I did not have cold enough place for the plants to stay dormant, and all got wasted. Since I have less space, I bought a refrigirator that has in its innards both my dormant rootstock and my pipe. Inside the insulated pipe is a smaller pipe filled with water, and around that is a terrarium heat cable. In my studies reading some scholarly work regarding walnut grafting and hot callusing I came to the conclusion that there has to be somewhat moisture surrounding the grafts, but also airflow. So inside the larger pipe is also moist spaghnum moss. I’ll likely try also other mediums, such as sawdust and vermiculite.
When the 21 days is over, I simply put them back to the bottom of the trunk. I use Inkbird thermostate, and it is absolutely perfect for this, keeps my fridge constantly around 4 Celsius.


Looks like a nice system. I’ve been trying to figure out where I can place the pipe and still keep the roots, etc. cold enough to keep them dormant. Do you have any idea how warm it is at the graft area?


That is a good suggestion and something I’ve thought about. I’ll have to take a look at them. My memory of them is that the interior hole may be pretty narrow, so that was my one concern.


About the foam pipe insulation …
It comes in different sizes., but…
It has a adhesive , peel and stick , strip on it , to seal it together, so, two smaller pieces can be stuck together, with that adhesive strip, and trimmed to fit any size pipe.