Hot Callus Pipe DIY


That’s what commercial propagaters use, or some form of hot water pipe.


I meant run the cable through the PEX as a spacer. I have one of those variable speed router controllers. I’m going to see if that works to adjust the temp.


Should certainly work. The PEX is a great idea.


I saw someone suggest a pool noodle. Wouldn’t the empty core be too small? If @Barkslip is suggesting a 2 inch foam pipe that’s a 2 diameter of empty space. I assume this is better than having a 1 inch space to stuff the wire and the graft union. The idea is to get the graft union inside the space being warmed by the wire not sitting in the foam wall right?


Going to build mine tonight. I just wanted to confirm that nobody has had it get too hot in the tube using these wires, correct? I see a lot of people have them in pretty cold rooms, but even in my unheated garage with our current temps it is staying in the high 50s into the low 70s when the sun is hitting it during the day. I would think the wire raises the temp in the tube by a certain amount above ambient temps, so if my ambient temps are hitting 70, would that potentially be letting it get too hot in the tube and damaging my grafts?


I have checked mine 3 different days and it is 84 inside the pipe. I’m not sure what the perfect temp is for every type of tree. Outside temp will be in the 70’s tomorrow afternoon and then 24 Friday morning so I am working on keeping my bagged up rootstock cold while the graft is in the pipe. Hopefully they don’t wake up too soon.


So the whole graft union is supposed to be inside the air cavity right? Not sitting nested in between the foam walls.


Yes, I cut my slits a little over half way down through the pipe and mine are sitting about 1/4 to 1/2 way down through the pipe with the graft union inside the air cavity of the pipe, high enough up to not touch the cable. This is my first time though, I’m a rookie at grafting and hot callus pipes! @Barkslip would be the best to answer these questions.


@JustPeachy / @zendog / @ctduckhunter

The idea is to never have your graft union touch the wire. Again, here’s a quick clip of post #1:


See that big & bold text? haha

Ok, all jokes aside now. Your union will fit every time inside the pipe, however, here’s the pipe I’m recommending and I will edit, above:

(I bought mine at a Menard’s)

I 1000% not 100% recommend 1.5" spacing between the slits. I cut my slits all the way down to the wire. The foam compresses together every time you put a graft in a slot and holds it in place… that’s not to say you may need to elevate the plant (when in containers) with whatever you have handy. I am using scrap lumber. 1.5" satisfies all these: 4" Stuewe “Treepots”, 2.7" width x 14" long Stuewe Deepots, & all barerooted-grafts.

Here’s the difference in size from what I will ultimately change once this grafting season is over. I started with 1.5" foam and will continue to use 2" (outside diameter.)



Hey Dax! I went to open the link in your post but couldn’t get it to work, so I searched it, came up with this page again, and opened it there - go figure.

Great post. Thanks for all you share here.


It’s a wonderful world isn’t it, yeah?

Have a good one, Mark.



Thanks for clarifying @Barkslip!


Giving this a go with some peaches and nectarines. I had it on my basement floor for a few days which probably wasn’t the best idea since it is a little colder there. Moved it up to the table.

Hope this works since I have some cool stuff from UC Davis like John Rivers nectarine and Harbrite peach.


Either or Tom. Basement floor or like you did. You want cool temps and darkness.



I’ll try to be short in thought but post pictures for enjoyment, as-well.

You can do a number of things with a hot callus system. What I’m doing is removing the bagged and bareroot grafted-trees and placing them in my second refrigerator. They came off the pipe after 21-days and go right in the fridge until my area is finished frosting/freezing & then I will plant them.

This grafting process is limitless for the most part. You may purchase rootstocks and as long as you keep the roots moist, you may put them in a fridge/walk in cooler or ??? and keep them dormant just as you would do with scionwood… and you can come back and graft on them anytime you have scionwood. I know of an outfit in the USA that has a big walk in cooler where they’ve held seedlings for 7-years prior to selling them. Of course they know way more than me about climate controlled (cooling.) So, yeah, I wrote about all this stuff initially but you can be clever with ways to go about hot callus pipe grafting. You think you should have a few rootstocks hanging around just in-case important scionwood crosses your hands, put a few in your 2nd fridge to be ready.

I should say to everyone that no matter what, keep the bud/(s) from the scion outside of the pipe! Even if your union (working area/cuts area) isn’t completely inside the pipe - that doesn’t matter. It’ll still stay warm being partly encased in the foam.

Well, now for pictures. Any grafts you see in containers broke bud so it was necessary to get them to (as much) sunlight as possible. You have to keep an eye on your grafts for buds that may break because once they do, they must see a lot of light or at minimum be in a window in your home… hopefully a south or west-facing…


As some of you know I’ll be growing (grafted) pecans, hickories, hicans, persimmons and pawpaws in the future and in 30" tall Treepots; Stuewe Treepots.

I have been grafting and building.

I had to replicate “above” - what was below. That’s the best way I can say it. This bench took 7-days to finish working 6-8 hours a day. I had built it to hold various size Treepots in “shoeboxes” - but it had to be modified of course to hold 30" Treepots. It’s a lattice system of 4" squares above and below. Empty containers weighing virtually nothing stay tight in place with 25-30 mph winds. It’s solid. 452 slots available on this bench.

Here are bareroot grafts (front) and the first run of grafts in well-rooted containers which I began graftin/putting on a callus pipe, the second week of January. I put them in those rubbermaids and stood them upright in containers in a dark area of my basement until they woke up. So I had to get them to light immediately. If you think ahead and if you have a greenhouse which I happen to have, I made room for all those grafts soon after & now they receive much more light.

The bagged/bareroot grafts go into my refrigerator (and should not freeze.) So turn yer beer fridges down a notch or two. Once May arrives in my zone 5 climate, I’ll remove them all, they’ll all be dormant still from having been in a ‘cooler’ and I’ll pot them up and let them wake up naturally in a nice, big, pot.

How I Graft: Dax
Treepot stand

These are the middle of Jan. grafts I did that are now inside my greenhouse. The mix for these is Pro-mix from the big box stores. I went all out and bought a professional mix from an outfit not so far away and would like to show you the difference. What I have is all organic and that’s all he mixes (is organics.)


Here I’m showing you to keep the rootstocks free of any stimulated growth that shows up.

Now the mix I purchased which can be seen at this link (scroll to the bottom for Tree & Shrub)

Here’s this organic mix

The ‘few’ bareroot’s that broke bud shortly after being on the pipe. It’s all the same cultivars for the most part - so tells you it’s all symmetrical in some way.

I love tip buds on hickory. That to me is pure beauty like someone else might think about spring bulbs!

How I Graft: Dax

Dax, your posts are some of the most informative to me here on GF. That’s a big deal since there are so many heavy hitters on here.


Thanks a million, Ram.



Great post @Barkslip ! Love the pics, sweet set-up! You have it dialed in. Do you have any problems with birds/robins when you put them outside. The robins are constantly messing with my rooted fig cuttings gathering materials for their nests, even stole some of my white plant labels last year. Now I have a few that are unknown, I should have labeled them in 2 different places, darn it.


Gotta stake. Other than that no… not here. never had birds taking tags.

No stakes = lots and lots of broken grafts.