Repotting blasphemy

I’m about to repot one of my favorite trees and began seriously thinking about the biology and physiology of repotting.
I agree with Ryan that this is open heart surgery. So, given this analogy, tell me if my thinking about post op repotting can increase the success of the repot.

I know the common recommendation is to not fertilize immediately and for a while because the roots are fragile and can’t take the shock of nutrients. This makes no sense. The roots desperately need to find water and food. The metabolites of the exposed cells of the roots begin to be depleted and within five minutes are gone. So spraying the roots with water during the repot prevents evaporation, but doesn’t replace the lost cell metabolites. The tree will have to cannibalize its vascular system to replace them. So, shouldn’t the spray contain a mixture of water and nutrients like calcium, phosphorus, etc. I think one of the goals of repotting should be to keep the root cells functioning in an optimal condition. So, after completion of the repot, wouldn’t it be better to give a diluted dose of bonsai organic liquid + Micrototal + (for me, some gibberellic acid)). This diluted dose will be good to keep the tree alive. Perhaps a weak fertilizer should be placed in the soil immediately below the tree root ball. Starving a person after surgery doesn’t make sense, does it?(Sorry if I missed this in one of the videos)

The other thought is that the transplanted roots need all the energy possible. So, I should keep as much foliage as I can and, perhaps, grow more. Also, since the fertilizer is so diluted, perhaps foliar feeding with a mix of organic fertilizer and Micrototal until the roots have recovered would help keep a steady state. Am I in a bonsai rabbit hole or thinking correctly?

I’d love to have some feed back about this.


Fertilizer is not food to a plant, photosynthesis is. The tree really only need sun and a balance of water and oxygen to grow and fertilizer being very salty competes with water uptake.
There are products on the hand that are supposed to help root growth, Rhizotonic is the one I use if I do a severe root pruning or if it’s a collected tree. I heard about it from Harry Harrington who tried it for a season and managed to get aerial roots on a hawthorn!
But isn’t it a bit late for a repot?


@Alex is right. No need to fertilize until clear signs of growth are visible.

No, I disagree. If fertilizer is not food for the tree, why bother using it? Where does the tree get the elements necessary for photosynthesis and growth? On the Forum, I think we should go deeper into this process, talk bonsai rather than glibly state dogma. I’d like someone to critique my proposition. All plants need the big three + micronutrients. When a newly repotted tree is placed into an soil devoid of elements, where does it get the npr to supply the elements necessary for photosynthesis?
Regarding the repot, I’ve been working this tree with Jim Gremel who I feel is the expert on atlas cedars. His concept is to allow a branch to grow to at least four nodes and then repot.


According to @ryan fertilizer is nutrition to a plant, photosynthesis is food. He asks the audience in the bsop stream spring fundamentals “what is food to a plant”, someone answers fertilizer and Ryans answer is “that is the last time we call fertilizer food”.
It’s additional nutrition to help the tree get as much energy possible knowing we stunt the trees by planting them in small pots.
I’ve never owned a ceder so I believe you and Jim know what you’re doing. It’s a great looking tree and I hope you’ll have success in the repotting process. Would like to get an atlas cedar myself but I’m not sure it would thrive here in Sweden.


After pruning the roots, the tree’s ability to pick up water and nutrients is severely diminished. It will logically take a few weeks for the tree to regrow the roots needed to efficiently move water and nutrients up. While the tree can still do this with the roots it has shortly after a root pruning, it can’t do it efficiently enough.

That said, if it takes the tree 2 or 3 weeks to grow these roots, and we fertilize immediately, we’re essentially wasting the nitrogen, which washes out in about 4 weeks. So, for those people who do this for a living, throwing away supplies makes absolutely no sense. Imagine repotting 100 trees in a year, and essentially wasting 100 fertilizer applications.

Also, as mentioned before, the fertilizer, no matter how diluted, will only make it more difficult for the tree to pull up the water it needs. So fertilizing shortly after has no real benefit to the tree, but can actually impair the recovery of the tree. Like you said, we don’t starve ourselves after surgery, but there’s a recovery period where we are careful, by resting and limiting our activities, to ensure that we don’t hinder recovery.

It’s a rule in bonsai for a reason. I would think that it did not become a rule out of sheer speculation, but out of careful observation of what produces better results.

If anything, try it out. Fertilize a tree immediately after repotting, and see if it makes a significant difference to the tree, and if it’s worth the expense on your part.

I’m all for questioning The Man, but in this case, The Man did an apprenticeship and has the relevant college education to back up his claims.


dear Endsurg,
here my 50 cents. I could agree with your arguments why fertilizer could be beneficial from the first place after repotting but I think three poinst are not concidered enought. First did you disturbe the balance of giving and taking between roots and foliage by repotting. Roots needs to reestabilsh their microbiology synergy and patch their wounds before able to take up nutritiens. The required energy comes from the stored resources. Second I think a lack of nutritions stimulates the roots to start search for nutrients, if they have everything in place why should the tree invest energy in produce more roots? The third idea is the salt nature of the fertilizer and its competition with water especially at very new root filaments. Water uptake is an active process in the roots and increasing the resistance for uptake seams to be counter productive. In contrast to that nurseries uses fertilized peat and heavy quantities of inorganic fertilizer when doing repotting. But they don’t cut roots excessively. I personally lost some trees because of excessivly using fertilizer during repotting.
best Balatus


Ooohhmmm…Balance of water and air… (CO2 ).
Carbohydrates (sugars) and cellulose(A form of carbohydrate) are composed ONLY of carbon, oxygen and hydrogen. Water and CO2 are DRIVEN through the photosynthetic cycle by sunlight to form carbohydrates.
The N(nitrogen, P(phosphorus), and K(potassium ) are used by the cells of the plant (and animals!) to manufacture proteins and enzymes that function in the cells to facilitate the reactions needed to do all of the work. Most of the time the photosynthetic process generates waste oxygen… Lucky us…
Plants only need a little nutrients to survive, Give them everything they can take in and they will go bizerk. Ever see a blue algae bloom in a lake? Over fertilization. Just like us–they need the micronutrients. Not too much, not to little. Ponderosa survive in high mountain crags with NO nutrients except what leeches out of the rock…
Plants will naturally close off cut roots and limbs. Same process you use. Diffrent enzymes. Too much trauma…you bleed to death. Their vascular systems are complex, too.
Learn the limits of root and foliage reduction for each species you have. Soil ,fertilizer, sunlight, heat / cold too.
I`m not a bonsai expert. I still have serious questions on trees. BS Biochemestry and 35 years of bonsai. I still learn from Mirai. I also read. A lot.
.thanks. Mirai.
Wow, did I just go full geek? Need a beer— must be low on vitamin P…


I wrote some articles were people tried to “fertiilize” with eigher glucose or aminoacids via foliage. they argued that since these product are essential for trees a supplimention must be beneficial. But I think the tree needs to uptake all basic components by its own to synthezise the higher molecules. To be able to do so a steady state system in the roots is essential (microbiology, too). The first meal after a heart surgery will not be pulled pork with fries. You start with glucose infusion ore a spoonfull of smasht potatoes.

The microbiom of plants is as complex as most life.
Im told…Some trees will communicate to each other through fungal microhriza systems …
Plants normally use fungus for micronutrients that they cannot absorb themselves. They share sugers the fungus cannot produce…sunlight…
We do the same with bacteria in our gut… vitamins.
Our skin processes proteins into vitamin D using sunlight…
The mitochondria in every cell of your body is actually a endosyombiotic bacteria that has taken up living there, with its own DNA, ya, it evolved that way millions of years ago… eucariotic and prokaryotics…
…now I’m geeking myself out…
On to the scotch…:yum:


Thanks Kurt for this lecture, that indicates that we have to see repotting probably more like a gut surgery than a heart surgery. If we disturb the microbiology of the gut all functions of the body are impacted and only the reestablishment of this microbio can fix it. And this goes best by bland diet then with cheese cake.


“Food” is imperfect because it’s an analogy; the important thing it points to is that for plants, the fundamental component is carbohydrates, not NPK.

People certainly have strong opinions on this topic. I’ve heard some say “don’t fertilize because you can burn the sensitive new roots”, or “if you fertilize too soon after repotting, you’ll discourage the plant from making new roots to search for nutrients”, and other various explanations. But I can’t say that I’ve ever seen any definitive research that shows either a benefit or a drawback to doing it.

I personally don’t think it hurts to add some weak fertilizer shortly after repotting, as it takes a pretty strong solution (high salt) to negatively impact the roots. Either the plant will take up some of the fertilizer or it will wash out. For the typical bonsai enthusiast, the cost of any fertilizer that may wash out of the container is pretty inconsequential.

It’s true that the plant manufactures its own “food” in the form of carbohydrates from CO2 and water, but the other “nutrients” provided by fertilizer are used to build new chlorophyll, produce enzymes and hormones, etc. One could argue there is a reduced need for these items right after a repot, especially if the tree isn’t actively growing new foliage. But do we really know that, perhaps these items are helpful for healing and regrowing roots.

Anyway…I don’t stress about it. I’ll sometimes skip a fertilizing session (water soluble) for recently repotted trees if I remember, but have never noticed any negative effects either way.


Anthropomorphizing plants can lead to wrong conclusions. Be careful with that.


I just want to clearify the item “food”.
Glucose, produced during the photosythesis from water and carbondioxide acts as the universal fuel to drive the engine of all cells (mitochondria). The resulting energy is used to drive all further processes. Endproducts of these reaction are carbondioxid and water again.
The elements from the fertilizer N (nitrogen), P (phosphor) and K (kalium) are used as building blocks for e.g. DNA and proteins or as signaling elements in the receptors or simple as salt in the cell to keep osmotic pressure constant. Without them the tree can’t grow. Lucky enougth soil (and all water we use too) contains Kalium and Magnesium (core element of the chlorophyll). Some bacteria could bind nitrogen from the air and phosphate is transported by the wind in form from dust (excrements and biomass) or simple by flies or snails or birds. So in reality a tree doesn’t die if you didn’t fertilize but is limited to the minimal offer from mother nature and on the long run will suffer especially in bonsai substrate.
The ability to take up these elements depends on the status of the roots and not of the existance of the elements itself, so if a root is inpaired by the repotting process it maybe aren’t able to take up nutritions even if they are available in excess.


Full marks.
In between, plants make cellulose. And carbohydrates.
Food for all.
Time …makes… coal and oil. Then we make more CO2…


So, coal and oil are renewable resources… after a few million years.


Soylent green…

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Personally have come to believe that if trees can take up H2O to keep trees alive they can also use added nutrients/stimulants. Personally use root stimulator 4-10-3 with .0004% Indole-3-butyric acid(active ingredient). However only use at about 50% strength recommended as once drowned trees in the stuff and killed them:sob:. This has seemed to work fine for me. After all don’t we put hormones/root stimulants on cuttings and air layers and it generates roots?

Continuing the discussion from Repotting blasphemy:
bonsai are trees. Trees have a finite amount of resources at any given time. ‘Prioritizing allocation of resources’ should be added to Ryan’s list of commandments, which are all pretty great btw…When you damage tissue you are forcing the plant to spend resources on repairing tissue. When you repot you need the tree to spend what it currently has stored, on repairing roots and creating new roots to replace what was lost. If you fertilize, you are forcing the tree to spend resources on metabolizing fertilizer INSTEAD of growing new roots or repairing damaged ones. The COST is about 30 to 1, how much carbon (food/resources)is required to metabolize one atom of nitrogen(fertilizer). That’s tree science. Google it…
If the tree is low on resources, theoretically, you can initiate a decline/death by forcing the tree to exhaust what little resources/carbon is left, to metabolizing nitrogen! The benefit of fertilizer is not realized by the tree until it’s been utilized to produce new leaves, and those leaves begin manufacturing photosynthate. Nothing is 100% in nature or absolute, always exceptions/wiggle room. But when you repot,you want whatever the trees got, to go to root formation and repair. Generally.