Foliar feeding - Do's and don'ts

Clicio

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Is foliar feeding of any use to bonsai?
If yes, how do you apply it, in which dilution and schedule?
 

Wires_Guy_wires

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To me, there's too much risk.
I spend some days on end away from home..
Micro/trace elements at regular recommended strength is something I do spray, once a month. The rest is through the soil.
 

fourteener

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Trace the history of the claim of foliar feeding and you'll find one study that suggested that maybe there is a slight possibility of minimal gain that comes through foliar feeding. That one study has fueled a claim of benefit through the foliage and a whole industry that lives on that one study. It isn't going to hurt your plant, just make sure you get as much, or more of it, in your pot.
 

Clicio

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To me, there's too much risk.

I am interested in these dangers.
Let me explain; I have used some liquid fertiliser in some of my plants last weekend, for the first time.
Diluted as per recommendations on the label.
And... Some Jacaranda seedlings didn't like it at all, wilting almost immediately and looking very unhappy.
Other plants didn't bother at all.
 

Wires_Guy_wires

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Seedlings have enough nutrients in their first set of leaves to last them 6-20 weeks. In regular potting soil that means overfert. is prone to happen if liquid nutrients are added.

Plants can take up some nutrients through the foliage, but loss of water is what leaves are built for. Too much salts on the outside means that the plant will dessicate itself. Since the nutrient rich water on the foliage evaporates, what's left is pure salts.
That's a risk, a risk that can be washed off easily if noticed in time. But that's the thing: only during weekends I have such time.
Roots can - to some extent - close themselves off, or lose much more water than leaves can.

The response greatly depends on the leaf type, salt tolerance, nutrient necessity and so on. This makes is super hard to come up with a universal foliar feed.

The trace elements though, are light doses meant for support. I'm fine with spraying those as recommended on nearly every plant I own. They're great in the battle against fungi for the same reason plants dessicate with high salt concentrations; metals and trace metals are so hard to move for fungi, so they wreak havoc inside their cells before they have the chance to lose them. The plants however, are fine with just a little extra.
 

Saddler

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My purely anecdotal evidence says foliar feeding works very well. I just started spraying all my trees with 1/10 recommended strength of 10-10-10 miracle grow every evening. A few trees that have struggled the last couple years have exploded with growth, as have every tree but the one in pure organic soil (so I repotted it and it is doing much better). Maybe it’s the foliar spray, maybe it’s just the daily fertilizing that hits the soil. Next year I’m going to do a small experiment with a few m maples from the same mother. One with just foliar fert, One soil fert, one both ways and One with without any fertilizer. The hard part will be remembering to do it in almost a year haha
 

milehigh_7

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One of the funniest and most epic wars on this site was about this very topic. Brings back memories of the "Attitude Era" on Bonsai Nut!
 

Melospiza

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At risk of starting a war, I will say that I have never seen a scientific source on evidence of foliar feeding. If someone knows a paper they can share, that would be great. Anecdotal evidence or "it works for junipers so it should work for everything else" doesn't really add to the body of evidence, if I may say so. Just from a first-principles perpective, foliar feeding does not make sense to me because leaves are designed for gas exchange through the stomata on their underside, not for liquid or mineral absorption. In fact, the cuticle on leaves prevents movement of molecules across the surface.
 

Wires_Guy_wires

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At risk of starting a war, I will say that I have never seen a scientific source on evidence of foliar feeding. If someone knows a paper they can share, that would be great. Anecdotal evidence or "it works for junipers so it should work for everything else" doesn't really add to the body of evidence, if I may say so. Just from a first-principles perpective, foliar feeding does not make sense to me because leaves are designed for gas exchange through the stomata on their underside, not for liquid or mineral absorption. In fact, the cuticle on leaves prevents movement of molecules across the surface.

Google for leaf disc culture, callus culture, suspended cell culture, there are loads of literature sources on the subject.. If you can be creative in thinking (for instance, you'd need to "imagine" that a suspended cell culture can be made from leaf material). I do acknolwedge that most of these materials do contain cut edges which allow transport. However, callus tissue is a completely closed cell, growing with whatever nutrients enter it.
Nitrifying bacteria might give some clues as well.
I'll see if I can dig up some solid literature for you. I want my definitive answers too.
 

Wires_Guy_wires

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Alright, let's end the war before it starts.
Plant physiology (Taiz, Zeiger, Moller, Murphy) is the bible of plant scientists. If they were to put out incorrect information, they would lose their titles, and a steady income of nearly 500 dollars per book, per student, worldwide.
Don't ask me how I got this screenshot.
Screenshot_20180514-194759.png
It's not the 'how' answer I was looking for, but it sure answers a question.
 

Clicio

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One of the funniest and most epic wars on this site was about this very topic. Brings back memories of the "Attitude Era" on Bonsai Nut!
No!
My intention is purely egoistic, and not to re-start and old flame war.
I have lost some plants and don't want to repeat this error!
 

Clicio

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Next year I’m going to do a small experiment with a few m maples from the same mother. One with just foliar fert, One soil fert, one both ways and One with without any fertilizer.
Please post your progressions in this forum?
 

Gustavo Martins

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Trace the history of the claim of foliar feeding and you'll find one study that suggested that maybe there is a slight possibility of minimal gain that comes through foliar feeding. That one study has fueled a claim of benefit through the foliage and a whole industry that lives on that one study. It isn't going to hurt your plant, just make sure you get as much, or more of it, in your pot.

have you traced that yourself? I just googled it (google scholar) and found multiple studies showing that plants and tree do absorb nutrients through their leaves. The rates vary among the different nutrients, but they are absorbed nonetheless. More, in aquatic plants, foliar vs root uptake of nutrients is exactly the same.
 

Wires_Guy_wires

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In general, I think it's safest to use 1:20 the regular strength.
But since you guys are up and scholaring anyways, why not google for the optimal tissue culture protocol and adapt the nutrient levels to the plant you'd like to feed?

I use the Nitrogen (both ammonium and nitrate/nitrites) contents of MS media as a guideline for my own nutrient levels.
Scots pine like 1/2 strength MS for instance, according to some literature, so I adjust my nutrients to whatever the nitrogen content of 1/2 strength MS is. But then again, I have MS nutrients available, so I didn't have to calculate anything other than 4.3 grams divided by 2.
That's for soils.
For foliar feed, if I would ever start doing that, it would be 1/20th strength MS.

In general I think it's better to not do foliar feeding at all, except for trace elements otherwise I would be contradicting myself. There's bacteria that should do it for you, and if not, there must be a reason why the plant doesn't accept these bacteria. The risk is too great, the gains are too small. There's evidence that foliar feeding can inhibit normal root growth, and depending on the type of nutrients (the down- and upside of organics!), you might just be laying down the ultimate snack palace for various not-so-beneficial microbes. It's not needed. It isn't necessary. I'm the kind of person that learned the hard way not to take risks. Especially not with trees, not again. ;-)
 

Tieball

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I use a foliage spray of HB-101. It’s not a fertilizer. I only started using it last year. The trees were very healthy with good green color last year. Autumn colors were bright. My trees this year are budding out healthy and leaves are very green this spring. This year is even the first year my Field Maple, Acer Campestre, has many healthy green flowers all over the new growth in the spring. So I can’t say it was because of the spray. I don’t have any test proof other than my trees are well and better, but I can say I have not experienced any negative results of using the foliage spray. Perhaps it just makes me feel better....and it is really all about me and my trees and my efforts in my conditions.
 

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