Hardwood cuttings and callusing

This should have been obvious, but after much trial and error in my Zone 5 basement and garage, I found the refrigerator works perfectly. I have a shelf at 38 degrees where cuttings callus in about a month with no bud break, which had been the problem elsewhere. (I’m probably just announcing that I’m the last person to discover this.)

Very interesting! I’m going to try it. Do you do anything to protect the cuttings from drying out? Thanks for posting this!

I was just going to do the newspaper burrito method as has been described here. I thought for successful callousing it needed really warm temps, like 75 degrees. So I’m confused. Thirty eight seems really cold. I am not an expert. I thought root development needed warm temps. Always learning something new, but now I don’t know what to do. I guess when I used the burrito method before there was significant bud break, but I had to tent them after potting up to gradually acclimate them to the air.

I had no luck with warm moist conditions at getting viable plants from hardwood cuttings. On the other hand the rootstock people back in the day always stuck cuttings directly in the ground at whatever was the ambient temp in a mild climate. That’s how we got Dr Huey in its splendid abundance. Some kinds of hardwood cuttings just turn black and rot in the refrigerator, with no effort to make callus. I do know that, from keeping autumn budwood too long refrigerated. I prefer to have some leaves on when making a cutting. Just yesterday I stuck a few from plants I was shipping out after they’d had some good hard frosts to go dormant with. Few leaves, not on all cuttings. Will watch and see.

I would like to try this refrigerator method. Where are you sticking the cuttings after they callus? At what temperature?
The burrito method always gives me great calluses, but the buds break and the cuttings die without rooting, pretty much invariably.

So, I’m in good company on the callus confusion? My current understanding is that rooting requires warm temps but callusing, which is healing rather than growth, occurs as long as the cells are active, which I assume is anytime the plant material is above 32 F? An article about callusing apple cuttings over winter in warehouses held at 40 F led me to the refrigerator. I packed these cuttings in barely-moist perlite in a sealed Tupperware container, but damp newspaper would serve the same purpose. These were species and near-species cuttings from rugosa hybrids, Persian Yellow and quince (which I understand will root in concrete). After callusing, I struck half the cuttings in a 1/2 perlite - 1/2 light potting soil mix in pots on a heat mat on the floor in a cool spot in my kitchen, trying to provide that warm root/cool stem micro-climate along the six-inch length of the cutting. The air is roughly 55 - 60 F and the soil 70 - 75 F. If these fail to root, the other half of the cuttings, still in the fridge, will be planted outside once the snow is gone. Hardwood is usually described as the easiest propagation method, but in my experience, softwood is more straightforward - and successful.

Wrapping cuttings has worked best for me in temps between about 60F and 68F. I’ve had folks try putting them in the refrigerator and all have found they tend to store well, like your produce, without bud break and without callusing. When held at 70F and above, the buds break and they begin attempting to form new canes and foliage. What has appeared to have been one of the most important issues to me is the condition of the material you use for wrapping. The more “dormant” it is, the more resources it contains, the greater the success. Where I’ve wrapped, that has appeared to have been after “winter” and before the plants have attempted to “break dormancy” and begin pushing new growth and foliage. Once that stage has been reached, the wraps repeatedly failed. Just to confuse the issue, Beth Hanna up in Paradise, California then experienced success in her wraps with commercial florist rose stems in late summer. To further confuse it, Sharon VanEnoo, in Torrance, California, has succeeded wrapping cuttings of polys and hybrid musks (Marie Pavie and Cl. Cecile Brunner from memory, and a few others) almost year round. She has been pumping those out all summer. Obviously, the condition of the material, the conditions under which it is held and its genetics all play parts. What I have repeatedly suggested to everyone is to keep trying, varying a facet each time to determine what is going to work best for them where they are, when they are trying it. If it helps, remember this was originally reported by a commercial, Australian nurseryman who wrapped his Fortuniana cuttings to produce his root stocks. Under my Zone 10a conditions, almost everything (including lilac) I wrapped, succeeded in the late winter through very early spring conditions, held in the temperature range I listed above. Here in my new Zone 9a conditions, it’s been quite a bit more hit and miss. Last year, I wrapped nearly four hundred cuttings of all types of roses grown in this part of California. Almost all callused but less than half succeeded. In the more arid, hotter Zone 10a, I planted them in moisture control soil because they would otherwise dry out in a day. The moisture control soil remained too wet here for the temperatures. In Zone 10a, during the period I found most successful, they could experience temps into the eighties after planting out. Here, we were lucky to get into the seventies. In both, I planted them deeply in the individual foam cups I used so only the top one to two inches of the cuttings were exposed to the air and light. As they grew roots and foliage, they hardened off, so once the cup bottoms are full of roots, I can slide the soil balls out, place new soil in their bottoms and replant the soil ball higher in the cups, exposing more of the buried canes. I’ve never lost any due to their not hardening off well.

Kevin, is that actual Persian Yellow or a hybrid? It would be pretty impressive if you could start cuttings of Persian Yellow. Getting callouses must be at least half the battle.

My experience with the burrito method has led to some successful rooted cuttings, but not a high percentage compared with how many sticks I started with. It sounds like others have had the same problem.

Of course, I can’t find the article I saw initially, but I did find a dry, but very thorough, USDA article - “Techniques of Tree and Shrub Propagation by Hardwood Cuttings” - that contains much of the same information. In a general section titled “Winter Callusing,” it reads: “If refrigerated rooms are available, the cuttings can be safely stored during the callusing period at temperatures of about 40 degrees F (4.5 degrees C) until they are ready to plant.” In a later section specific to roses, this idea is reiterated: “In areas with severe winters, cuttings may be made in late in fall or early in winter, tied in bundles, and stored in damp peat moss or sand at about 40 degrees F (4 degrees C) until spring, when they are planted in the nursery row.” Here’s the link: https://www.nrcs.usda.gov/wps/portal/nrcs/detail/mt/home/?cid=nrcs144p2_057727

The burrito method, as I understand it, is the material used, rather than the conditions provided. I think I would have the same result using that method, but I stopped the paper and have cubic yards of perlite.

Joe, as far as I know, this is actually Persian Yellow. I live in a relatively undisturbed historic district that cries out for rustling and this rose grows through a fence into public property. I’ve never seen this plant affected by disease, despite serious neglect. I’ve stolen pollen for years and decided to move from misdemeanor to felony. I’ll let you know if this actual Persian Yellow actually roots.

And I agree with Kim: Find what works with what you’re working with where you’re working with it.

After two weeks on the heat mat, this appeared. I’ve never had a cutting send a shoot from below the rooting medium. There are no roots visible yet along the sides of the cups, but I’m encouraged that something is going on down there. The buds on this, and the other cuttings, are otherwise swelling normally.

I’ve done it. Two weeks ago I took these cuttings. Treated them as per this article and I’m delighted to show that calluses are already forming on the cuttings without any special care.
I plan to pot them up this week. Any suggestions?
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Congratulations! How to proceed depends upon your weather for the next several months. If it’s windy, more arid with high evaporation and warmer rather than cold temps, it will work better to plant them deeper so only the top inch or so of the cutting protrudes from the soil. Watch for root growth in the bottom of the pots (smaller pots like 16 oz foam cups, NO PAPER, it won’t last long enough, with drainage holes poked through their bottoms), when you can lift them by adding more soil to the pot bottoms, placing the bottom of the soil ball in the pot then begin working the soil from around the cutting into the pot so you have in effect, raised their planting height. If it’s chillier and wetter where you grow them, they may be planted higher now, probably at the level you wish them to grow. The trick is to tailor how they’re planted to what your conditions are for the next several months so they don’t dry out prior to forming roots and beginning to grow on their own. If you’re growing them in a green house, pot them as you want them to grow. You can either occasionally mist them so they remain moist or maybe the green house conditions are sufficient to keep them from drying out before they root. Good luck!

An update on the Persian Yellow cuttings… callusing, bottom heat and general pampering went nowhere. Although the cuttings appeared viable for a remarkably long time, I had 100% failure. Two cuttings that I took last fall, left in the fridge until February then stuck in 2/3 perlite and 1/3 peat and put outside on the north side of the houe are rooting. I did move them into an unheated garage if the temperature dipped below 25 F or so. It’s been an unusually cold and wet spring, so that must be preferfed.

Congrats, Kevin! Thanks for posting these results. It is very interesting.

I’d like to root Hazeldean and Prairie Peace in some sort of extremely easy way. Your exact method wouldn’t work here, with below-zero temps in February. I imagine the average temps were in the 40’s or 50’s for your cuttings this winter?

I took some cuttings from three roses last fall with the intent of callusing them and starting them. I left them in a plastic bag in the bare root building all winter, which ends up between 34 and 40 degrees. When I finally got to them a few weeks ago, some had callused, but the calluses had somewhat dried out. The others I re-trimmed and put them all in moist vermiculite at room temperature for about two weeks. Excellent callusing as a result, with sprouts of about 1 inch. I potted them and now have them in a greenhouse under a bench loosely enclosed in a plastic bag and they’re looking great so far. I was a little surprised that it worked so well when they were neglected all winter.

I’d like to come up with a method of callusing our native red-twig dogwood. We have a selection of which we sell quite a few each year. Currently we use soft-wood summer cuttings in sand under mist. Usually we mess them up somehow - let them wilt or keep them too wet allowing disease to get in there. If we could callus them, maybe they could be stuck directly in the field in the manner of a hybrid poplar or willow. My mistake in earlier attempts was to use too high temps, causing too much sprouting. I think I should try the 38 degree thing.

Thanks, Joe! According to NOAA, Spokane’s average temps from Feb to May were 29, 40, 46 and 52 (I’d shave at least five degrees for my location), but, yes, our coldest temps were behind us. I did bury the cups in a five gallon pot to moderate the fluctuations and the soil in the pot froze frequently. On drying, even sealed in barely-moist perlite, some of the various cuttings stored from November until February seemed to be drying out. For instance, the only quince that rooted were the ones I stuck last fall. And dogwoods are usually so cooperative - especially layering, but you likely need more than that might provide, right? It may be you’ve just been trying too hard. That’s been my own conclusion from this.

Joe, this dogwood tree/plant you are talking about can you obtain semihardwood/hardwood cuttings. i know this is a long shot, I am in the grape industry here in Australia and we take cuttings of varieties we want to expand our vineyard in early Winter, then make a box arrangement out in the open, we use 2" of sand on the bottom and place the cuttings(50in a bundle) on this inverted, then completely enclose this in sand at 2" outside wall and top. The box arrangement is what we call corrugated iron(roofing iron), I guess you can use any form of iron. Over the top of the 2" sand we place black builders plastic after washing the sand all around this box thing and bundles. We take them out in our mid Spring with callous and or fine hair roots, mostly hair roots. We originally used ‘Chinasol’ as a dip prior to this, now we do not, not saying it worked better or not. In your zone Joe you would have to adapt it a bit I think, maybe inside somehow.

Thanks for the explanation of your grape rooting method, David. Yes, our temps are the problem with duplicating that. I’m going to have to find a 40 degree place…my bare root buildings are a little too cool until spring. Maybe.