I thought this was more appropriate under a new topic.
Using the burrito method:
I’ve been wondering about this, as I have been very successful using the burrito method for several years but I don’t use hormones. Some varieties, and also thicker cuttings, callous very well but never send out roots. I was under the impression, though, that rooting hormone encouraged callousing, not root growth. Am I wrong about that?
Hi Judith!
Auxin, the class of hormones in rooting powder, are thought to promote rooting in a two step process for plants like roses. The first step is root initiation or the formation of regions of dividing cells that may later develop into a root. The second step is root elongation from that initial. Relatively speaking there is a higher optimum concentration needed to initiate roots versus promote elongation. Too much auxin still present when it is time for elongation can inhibit that step. Plants have a lot of natural hormones within them that are doing things and then interact with whatever hormones we try to add to the situation. There are other hormones involved with rooting that scientists are still learning about, but auxin is the key one and one we typically try to manipulate. Callus in tissue culture and other situations can develop from a mix of auxin and cytokinin. Cytokinin is a hormone that is involved in cell division and on a larger tissue level promotes shoot development. Auxin on a cellular level encourages cell elongation. When they are fighting each other we can get excessive callus (lots of cell division and expansion for callus, but the tipping point of enough more auxin for the system to go towards roots may not happen). In difficult to root roses as well as other plants there definitely is more to learn about why rooting is difficult and what we can do to help overcome that challenge. Perhaps there are other secondary metabolites in the tissue that makes it difficult for rooting to occur. Sometimes time of year, physiological state of the plant material, environment, etc. can be manipulated to help.
I hope someday we can better understand why spins, rugosas, eglantine, and other roses tend to be difficult to root from cuttings and how we can overcome those limitations.
Some varieties are just flat out pigs to get to root, Judith. Then, you will find some cuttings from a rose which roots well that just don’t. I’ve found planting them deeply out of the burritos keeps them moist, dark and cool enough for the majority to eventually root. Not 100%, but in very many cases, close enough for government work.
I’ve found the same thing, Kim, especially with thick cuttings. I shove 5-7 deeply in a 1 gallon pot, put them out under a bush which keeps them humid and some will root.
That’s my best method for hibiscus sinensis and it appears to also be working for the Banksiae.
So David, if I’m reading into your post correctly, if a cultivar callouses easily (root initiation), then using rooting hormone would not be necessary, and indeed might hinder root elongation by causing the production of too much auxin? The question in my little brain is, how to initiate root elongation from the callous in cultivars that (in theory) produce too much auxin, hindering the second part of that process?
Years ago here in OZ you could buy 2 different rooting hormone powders (soft tip and hardwood cuttings) I suppose the difference was the amount of IAA in each prep. Now it is gels, which I think are better. The preparation of the cutting prior to applying gels is just as important. Just cutting off pieces of plant material may not be enough, extra cutting may be required to expose more cambium layer or cutting just below a bud joint. I found pithy cutting always rotted, but if you use thin (pencil thick) very woody cutting of these cultivars success was better using jells.
Warren
David’s points are very interesting to me. I have noticed in the past that the affect of IBA on my cuttings varied seemingly with the time of year. Sometimes it seemed to help, but at other times, the cuttings I treated simply would not root, whereas the untreated ones would. I never did a side-by-side study with controls to really confirm my observations, but just stopped using rooting hormone altogether.
There are of course various concentrations of hormones for use with different plants. Hormodin, for instance, has a 1, 2 and 3 series based on how concentrated the hormone is (0.1, 0.3, and 0.8% respectively, as I recall). I don’t recall their literature distinguishing between the different roses in terms of recommended dosing. (I’m guessing my failures were from too strong of a powder.)
Looking at their site now, I see they recommend the weaker (#1) formulation for roses, whereas “Hormodin 3 is prepared specially for propagating the more difficult to root varieties, including many of the evergreens and dormant leafless cuttings.”
Hmmm… Yeah… My recollection is that actively growing semi-ripe cuttings of teas and chinas were the ones that fared better without IBA, but I have pretty deplorable memory, admittedly. (Knowing me, as the poor starving art student at the time, I probably figured the stronger formulation got me more bang for my buck! LOL.)
I think the short answer, Judith, is “yes”. (Is that correct, David?)
That is why I stopped using rooting hormone. I had the same experience as you did, and was getting better results without it.
Meanwhile, I took a bunch of cuttings this December and using no hormone, and the burrito method, almost ALL of the ones now rooted and in pots (about 25) are about the size of a pencil LEAD or a little thicker. None of the larger ones have rooted yet.
Smaller cuttings have had great success for me when they were happy and not dormant. THe (full) pencil sized cuttings worked better as dormant (deciduous) cuttings in a colder clime in the past. I haven’t done so much of that since moving back to a warmer climate. But I’m making very broad generalizations from very limited experience.