I’m not sure if this qualifies as advanced but I thought it was a great idea that I should share. I should also add this is not my idea but one I picked up from Growcast podcast (link below).
As we all know topping can be a stressful experience for the small plant. It is usually a trade off between loss of growth and breaking apical dominance to allow for a more even canopy. In the podcast they discussed research into pre selecting cuttings while still on the mother, topping the branch and then leaving it for 7-10 days to recover. The mother is able to take that stress without many problems and when you are ready to take that cut it is already redirecting energy into growing those side branches. It’s so simple I could not believe I hadn’t heard it before. That being said, if this is a well known thing that I somehow missed please be gentle with me
Whilst removing the growing tip of a branch will encourage the side-shoots to develop, it will also slow root growth which might be detrimental to the rooting of the cutting.
Auxins are a plant growth regulator which influence branching and rooting. Whilst the main growing tip is present, the auxins in it will encourage root growth and inhibit side-branching… and if you remove the main tip the removal of those auxins will allow the plant to put more energy into growing the side branches below, but this energy has been diverted from the growing of roots - so your method may have benefits for the clone but it might slow down the rooting mechanism. addition of rooting hormone will help but i’m not sure what you are really gaining from the whole process.
@VerdantGreen I’ve thought the same thing, but we might be mistaken.
The auxin is being produced mostly by the apical shoot, but technically there is always an apical shoot. So the question is, “During cloning, is there a difference in auxin production between these two?”
I’m still a little unsure of why topping the secondary branch would be beneficial. Listening now
I do this prep on mums all the time a week before taking cuts along side my other preps : ) I see no difference in rooting : )
If I’m not being lazy and have the time , I will also remove the leafs that would be normally removed from the cutting later , I do that now too , the trimming of the 1/3 -1/4 tips of fingers from remaining top two fans that are left I leave trimming off till I make the cut : )
I also one week befor cuts , feed higher pk in feed and reduce n ( use bloom feed and at lower ppm )
The low n forces cuts to fire out roots quicker looking for food
If there is high n in cuts , cuts won’t feel the need to root and will just sit there and cuts will eventually show p and k defs , and if the do root 2-3w+ , they will have to take time too recover ( lost time )
The plant cannot store as much p and k in leafs , so this is usually what defs show first , so topping up on mum befor hand is good move , p for roots and k for plant health : )
If growing new clones for first time , the topping lets me see the bushy types and the true bat types helpin me decide how best to run them again kind of : )
The most auxin is in the apical shoot, and when you remove it this auxin gets removed with it, and yes the next shoot down becomes the apical shoot… but it won’t immediately have the same levels and, during this time, the energy of the plant is diverted from root growth to branch growth… so asking a plant to produce both side branches and roots at the same time is kind of making the plant processes work against each other. That said, i havent tried the cloning method so maybe the rooting hormone (which has auxins) makes up for the lack ? or maybe the complete lack of roots influences the auxin effect?
I grow intensively in very height restricted cabinets and so i do a lot of topping and training - and in a more general sense i avoid topping and up-potting at the same time, because that is asking the plant to do two things that are somewhat in conflict with how PGRs and plant processes work.
This is where I’m thinking our assumptions about the hormone levels might not hold up. It would be super interesting to see what the auxin levels actually are in an untopped clone, vs a topped clone.
Without the data it’s all just supposition.
The cutting is in cast off low lighting , it will fire out the roots first as it has to match the plant mass above first , befor it will start to grow again : )
I am in no way an expert on this but the position the guest on the podcast took was that the mother may slow but is in a much better position to be able to absorb this stress. Within the 7-10 days you wait after topping she will recover and then you area able to take the clone without the loss of growth from future topping. David K mentioned this was lab tested and had shown good results but without testing it myself at home I cannot say for sure.
He left his email at the end of the show and said to reach out with questions. Maybe I’ll email him for further information on this technique. I’ll post an update if I hear back.
I’m no expert either… just trying to apply what i know about how plants respond to stimuli to this idea… i generally try to keep things as simple as possible. It’s an interesting idea but, even if rooting of cutting wasn’t compromised, i’m not sure how much you’d gain over just taking the cutting 7-10 days earlier and topping it after it had rooted into its first pot for instead! (keeping in mind you have 7-10 days extra time to play with)
