Fertilizing question

[August44]

I read that one should NOT fertilize newly repotted trees for 4-6 weeks. I will assume that that is because high doses of nitrogen may burn newly trimmed roots?? Would it ok to use an organic type fertilizer that is 2-3-1 or a non-organic fertilizer that is 0-10-10 on these trees in the first 4-6 weeks?

 

[KLSbonsai]

Using an organic fertilizer, my experience and from the info I follow, I start after 10-14 days.

 

[A. Gorilla]

You just don't want anything competing for access to the feeder roots on any sort of compromised tree. They need water and air, first and foremost. Fertilizer can wait until new growth is clearly appearing.

Nitrogen specifically is beside the point.

 

[Dav4]

I have historically fertilized shortly after re-pots with no ill effects seen... whether these trees benefit from the feed I can't say as compromised roots don't absorb nutrients effectively until new feeder roots are established. You should know the trees I speak of are all in good soil and are clearly growing when the feed is applied and are copiously watered between feedings.

 

[August44]

You just don't want anything competing for access to the feeder roots on any sort of compromised tree. They need water and air, first and foremost. Fertilizer can wait until new growth is clearly appearing.

Nitrogen specifically is beside the point.

I appreciate the answer...I'm new to all of this and do not fully understand what you just said...."competing for access to the feeder roots" and " Nitrogen specifically is beside the point". Could you explain that a bit please? Thanks, Peter

 

[Anthony]

Normally fresh soil with organics, is good enough for month or two
with no fertiliser.

Ask also for someone who does 100 % inorganic soil mixes.
They would be using the oil seed meal [ organic fertilisers ]

By the way , it is wise to find out how long, the person who is giving the advice
has been growing bonsai and see examples of their trees.
Good Day
Anthony

 

[leatherback]

Roots that have loads of fertilizer have little reason to grow, so goes the story. The other is burning roots. I do not believe either one. The main reason for not fertilizing in my book would be that the roots have just been trimmed and won't be able to use it, so most of it just flushes out by the next watering. I am not too worried and will fertilize repotted trees if I happen to be watering with fertilizer.

 

[Wires_Guy_wires]

Some reasons not to fertilize:
- Organic fertilizer is a buffet for micro-organisms, both bad and good. After repotting, there are numerous points of entry for bad ones to get in. Some microbes respond with heavy growth if a plant sends out damage related signalling molecules. Both the bad and the good. Whoever ends up on top? We can't be sure.
- Too much fertilizer will kill developing and established roots, no matter if there was a repot or not.
- It's a fact that roots grow less if they're supplied with the right amount of nutrients. Especially nitrogen seems to have this inhibiting effect.
- The way bonsai people dose their nutrients always amazes me; they put little packets of highly concentrated nutrients on certain spots. This can actually kill roots due to overdosing them. I'm sure it has its benefits in established plants, to provide localized growth improvement. But with restorations going on, this could very well be a wrecking ball. We give our kids bacon and pork chops, but we don't try to stuff an entire wild boar down their throats.
- It's hard to dose right, how much is needed for a new container with a different size from the previous? There is no rule to abide to (well, actually there is, but that's some deep science). Especially for beginners, it's hard to estimate the demand for nutrients of a certain plant. If you want to be totally safe, go with the safest option; don't feed until it's back to its original state.
- Nutrients can block the soil from breathing properly and they can cause algal blooms. Algae are bad.
- Plants can keep growing when they're fertilized and give off the vibe that they're entirely healthy, until winter comes and then suddenly die due to a lack of roots.

Some reasons to fertilize:
- The plant needs the building blocks to repair damage, where is it going to get them in a barren soil?
- Switching from a heavily fed soil to a soil that is devoid of nutrients is a GIANT shock to all plants. Why isn't anyone watering consistently with deionized water? It's probably because the water is so empty, it will extract nutrients from the plant. I wouldn't want a shock + another shock. I prefer a steady change of environment; all of my soils are premixed with nutrients. This eliminates at least one shock factor of the two.
- Who needs rapidly grown roots? We need healthy and strong ones, if they take extra time because they're of higher quality, then I'd prefer those.
- Roots, and all other plant parts keep consuming nutrients even when they're damaged. Buy your wife a floral bouquet, and the florist will hand you a pack of light fertilizer for free. If they're not making money off of it, and it doesn't benefit the plant, why would they hand it out to you? What do bouquet buyers know about horticulture? They could have sold you that pack for an extra 5 bucks!
- Even if the roots have limited abilities for a while, they still function albeit in a more relaxed state. The rest of the plant is still high in demand for nutrients. Unless you're taming a beast, you might want to consider feeding it. This is a breaking the cycle versus not breaking the cycle kind of thing.
- We want auxins and other hormones to do their job. Have you ever looked at the chemical composition of indole-3-acetic acid? It needs a nitrogen atom. Where would a plant get that? From the air? Where do those air-nitrogen-capturing bacteria usually live? Right.. In the roots we just cut off..
- We don't want our plants to spend their reserves on both growth and restoration, while they could just be not spending their reserves at all. That's what reserves are for! For those extra extra hard times.


These are the main arguments I could come up with, both sides have very sound reasons and I believe everyone should decide whatever they feel is best. I have never found any negative effects from feeding a repotted plant. I even feed my collected plants.

 

[Gary McCarthy]

good article - http://www.evergreengardenworks.com/fertiliz.htm

 

[August44]

Brent must have a Dr. degree in this stuff. Great article! Thanks.

 

[A. Gorilla]

I appreciate the answer...I'm new to all of this and do not fully understand what you just said...."competing for access to the feeder roots" and " Nitrogen specifically is beside the point". Could you explain that a bit please? Thanks, Peter

Things diffuse into roots indiscriminately. Molecules traveling from an area of high concentration to an area of low concentration. If some useless mineral like Titanium is in the soil, the plant will take it anyway.

Priority number one for root health? Ideal balance of water and air. If that doesn't exist, forget the rest. Anything else can only further encumber the process.

Stands to reason that the degree to which roots are messed with, the more one should consider just air and water At best fert may do no good, at worst it gets in the way of what the roots really want first and foremost.

Seems logical that you'd want to see the tree processing stuff and actually growing so you know the churn is turning and ferts are being used and not wasted (or using up valuable surface area which would be better used for just water.)

 

[KLSbonsai]

I'm assuming Anthony's comment was directed at my reply considering I have only been on this site for a short while. I have been practicing bonsai for about five years, but I have 29 years of horticultural experience. Including seven years special in transplanting specimen trees. So I may not be a frequent poster here but rest assured Anthony I do have the horticultural background to back up my comments.

 

[0soyoung]

Does anybody's opinion change if they are told that most adsorption occurs through the extended walls of single cells of the root epidermis, a few millimeters behind the growing root tip?

My main take away is that a freshly cut root has an impaired capacity to adsorb anything until a few millimeters of new root growth has occurred.

 

[leatherback]

a freshly cut root has an impaired capacity to adsorb anything

My point exactly

The main reason for not fertilizing in my book would be that the roots have just been trimmed and won't be able to use it,

 

[M. Frary]

I've fertilized on the same day after a repot/root trim if that day falls on a Saturday.
Saturday is feeding day here.
I pour Miracle grow on them at least once a week.
I mix 3 to 5 times the amount it says to use in the directions.

 

[Gustavo Martins]

I will assume that that is because high doses of nitrogen may burn newly trimmed roots??

IMO this makes no sense. It is also said that nutrients will kill new tender roots after repotting. My question is why does not nutrients kill new tender roots at other times? Or are we assuming that plants only make roots immediately after repotting???? Makes no sense.

IMO a regular dose of ferts will do as much good after repotting as on any other time of the year. I repotted and put the fertiliser bags back in my olive yesterday.

 

[Brian Van Fleet]

IMO this makes no sense. It is also said that nutrients will kill new tender roots after repotting. My question is why does not nutrients kill new tender roots at other times? Or are we assuming that plants only make roots immediately after repotting???? Makes no sense.

IMO a regular dose of ferts will do as much good after repotting as on any other time of the year. I repotted and put the fertiliser bags back in my olive yesterday.

I was taught the “burning” associated with feeding freshly pruned roots has more to do with the granular non-organic frets which have a high concentration of salts. Higher concentrations of salts in the soil causes water to move from lower concentrations (roots) and into the higher concentrations (soil), drying out the roots.

 

[Anthony]

No @KLSbonsai ,

not directed at you.
I have said that bit a few times before.
More a polite suggestion that the new folk read at the Archives.


I ask who are you supplying the NPK to ?

The cut roots [ and broken by washing to bare root, the cilliary [ fine root hairs ? correct ] ]
or the microbes that work with the roots ?

Normally we wait one month before suppling 1/3 strength fertiliser.
Result - in full sun, strong hard green leaves often dark,
No one bites unless you are a parasol ant or grasshopper /locust.
Then the ant shrikes come.
Good Day
Anthony

https://neotropical.birds.cornell.edu/Species-Account/nb/species/barant1/overview

 

[0soyoung]

I was taught the “burning” associated with feeding freshly pruned roots has more to do with the granular non-organic frets which have a high concentration of salts. Higher concentrations of salts in the soil causes water to move from lower concentrations (roots) and into the higher concentrations (soil), drying out the roots.

This is indeed a fact, independent of the root pruning - osmosis across a membrane.

Organic ferts assay as something like 4-1-2. whereas chem ferts are usually far more concentrated, something like 12-3-6, say --> one-third the amount of chem fert is pretty much the same salt and N-P-K dose (per this example).

Does anybody's opinion change if they are told that most adsorption occurs through the extended walls of single cells of the root epidermis, a few millimeters behind the growing root tip?

My second take away is that pruned roots are no more prone to 'burning' that unpruned ones.

 

[Gustavo Martins]

This is indeed a fact, independent of the root pruning - osmosis across a membrane.

Organic ferts assay as something like 4-1-2. whereas chem ferts are usually far more concentrated, something like 12-3-6, say --> one-third the amount of chem fert is pretty much the same salt and N-P-K dose (per this example).


My second take away is that pruned roots are no more prone to 'burning' that unpruned ones.

Exactly