Dead Leaves as Fertilizer

[DrTolhur]

Trees naturally have a recycling program built in, where they drop their leaves in the fall, the leaves decompose over the coming season, then the trees can presumably reabsorb some of the nutrients in the leaves for later use. Is there any value in recreating this with bonsai? Either with defoliation or in the autumn, take dried leaves, crumble them up, and sprinkle them on the soil like fertilizer. My guess is that, sure, it might be of some value, but it's easier and more controlled to just use actual fertilizer, but I'd like to hear others' thoughts, especially if anyone's tried such a thing. It seems likely that the fertilization value of leaves would also probably be fairly small compared to dedicated fertilizer.

 

[ShadyStump]

Anyone who's mixing compost into their substrate mix is already doing this.
Because our trees are in tiny pots, and the same worms and microbes that's break down that leaf mulch are sometimes the same that eat your tree there's little space for doing it in the pot. The decomposition process also can produce heat that may damage roots.

Adding the raw mulch to substrate or spreading it on top can can help with water retention if you need it, but in the sort of closed environment that pots create, you're probably safest not trying to compost in that. Just rake your leaves and lawn clippings like normal, then start a compost pile. Mix some in when you repot.

 

[Shibui]

Most growers are aware that leaves and other debris is where many pests and diseases hide and breed.
Keeping fallen leaves may recycle some nutrients but are the potential pest and disease problems worth the few nutrients you'll gain?
Collect and compost fallen leaves and prunings if you feel the need to close the loop but You'll still need to add more fert to counteract leaching from regular watering.

 

[ShadyStump]

Most growers are aware that leaves and other debris is where many pests and diseases hide and breed.
Keeping fallen leaves may recycle some nutrients but are the potential pest and disease problems worth the few nutrients you'll gain?
Collect and compost fallen leaves and prunings if you feel the need to close the loop but You'll still need to add more fert to counteract leaching from regular watering.

I do imagine that leaching effect is considerably more in a tiny pot, but from gardening I know that a very well balanced nutrient dense feed can be achieved with just compost. If composted properly, not so many nutrients as you might worry about are flushed away.

Just saying that it is viable to grow and fertilize bonsai entirely with compost. Before chemical fertilizer it was done with that or manure.
I would agree, though, that this may not be as efficient growth as with modern chemical ferts properly applied.

 

[AlainK]

Most growers are aware that leaves and other debris is where many pests and diseases hide and breed.

Right! The only leaves I put in my compost are Zelkova leaves : I've never ever seen any disease or pests on them.

 

[Gustavo Martins]

I do imagine that leaching effect is considerably more in a tiny pot, but from gardening I know that a very well balanced nutrient dense feed can be achieved with just compost. If composted properly, not so many nutrients as you might worry about are flushed away.

Just saying that it is viable to grow and fertilize bonsai entirely with compost. Before chemical fertilizer it was done with that or manure.
I would agree, though, that this may not be as efficient growth as with modern chemical ferts properly applied.

I may be wrong here but I think that compost is not a fertiliser for the plants in itself. It does feed the soil microbiota (fungus, bacteria and arthropods) that in turn feed the trees. Not sure this will be of much use in a pot.

 

[ShadyStump]

I may be wrong here but I think that compost is not a fertiliser for the plants in itself. It does feed the soil microbiota (fungus, bacteria and arthropods) that in turn feed the trees. Not sure this will be of much use in a pot.

My understanding- I'm no expert in soil chemistry, just a gardener- is the microbiome responsible for organic matter decomposition breaks down the matter into various chemical components, eventually to a point where those chemicals can be absorbed by the plant roots.

One place to start thinking of how this works is baking bread. The yeast feeds on the carbohydrates- the starches and sugars- in the flour and creates carbon dioxide as waste. The CO2 is what makes the dough rise.
Other microbes will feed on other matter, producing other waste products, like amonium compounds, which the plant absorbs the same way as lab produced amonium compounds in chemical fertilizer.
Using manure, the digestion of the animal it came from has done much of the work already, so the nutrients are already largely available for the plants. Hence it's possible to burn the plant with chemical fertilizer, less likely but still very possible with manure, but very unlikely with compost.

I would agree that in a pot it is more difficult to keep such processes going on their own, especially when compared to the vast forest floor, but it has been done since bonsai was invented.

 

[Bonsai Nut]

Yes, dead leaves contain nutrients. No, they don't come CLOSE to the nutrient value of decent organic fertilizer. Part of the reason why is that deciduous trees are very good at reabsorbing nutrients in the Fall when the tree is preparing to shed its leaves. Dead leaves are mostly carbon, with very low values for other elements/nutrients. That doesn't mean don't use leaves... but understand that you would have to use a lot more volume to deliver the same fertilizer value... which in turn would not generally be what you would want to do with a potted tree in mostly inorganic soil.

For example - N/P/K numbers from a mixed/municipal leaf analysis yields: 1/.1/.4 (in terms of % concentration dry weight). (Rutgers study here)

For comparison - Jobe's Organics (just a general organic fertilizer broadly available) has a guaranteed analysis of 4/4/4. So you would have to use 10x as much leaf mulch (by dry weight) to deliver the same amount of Potassium as in Jobe's.

Chemical fertilizers are even stronger. And, when using leaf mulch, you need to make sure you understand which leaves you are using. Oak leaves are acidic... which can be good or bad depending on what you are trying to do.

I'm a big proponent of mulching leaves and leaving them on your lawn in the fall. However I think practical use for bonsai is limited... and may be harmful if you find yourself having to add too much to your soil.

 

[AlainK]

a guaranteed analysis of 4/4/4. So you would have to use 10x as much leaf mulch (by dry weight) to deliver the same amount of Potassium as in Jobe's.

You mean phosphorus ?
N: Nitrogen
P: Phosphorus
K: Potassium

Pho... is before Pot... in alphabetical order. I could never remember, a friend gave me this mnemonic trick.
The percentage of K (Potassium) seems to be equivalent in both the mulch (1.1.4) and Jobe's fert (4.4.4).

And thanks for the links

 

[ShadyStump]

You mean phosphorus ?
N: Nitrogen
P: Phosphorus
K: Potassium

Pho... is before Pot... in alphabetical order. I could never remember, a friend gave me this mnemonic trick.
The percentage of K (Potassium) seems to be equivalent in both the mulch (1.1.4) and Jobe's fert (4.4.4).

And thanks for the links

Think that was a 4 vs a 0.4

I will say that the science is clear, there is no real side by side comparison between compost and chemical ferts. As my ex put it, it's like putting your plants on steroids.
But that's exactly what makes them tricky to use. Wrong dosage or routine and you do more harm than good.

I am big proponent of using a well balanced compost- not just leaves, but all manner of organic material- for all growing needs. This and crop rotation (which for bonsai is done via repotting) makes all the nutrients your plants could need readily available, without waste, and with minimal risk to self or the plant when done with consideration.

COMPOSTING CANNOT HAPPEN IN A POT though. Like other soil components, you have to prepare it on the side, ensuring its quality, and add it to the mix when the time comes.

 

[AlainK]

Think that was a 4 vs a 0.4

Oh you're right !

Celsius vs Farenheit is not the only thing we, the rest of the world, have to deal with and be aware of.

For instance, 1,314 is for you "one thousand three hundred (and - in British English) thirty-four. In France, it's written 1 314.
In france, it's "PI", what you would write : 1.314
And we would never write ".4", but "0,4", though because of the influence of American English, we more and more often see "0.4".

OK, I got it now.

Language is not a matter of words, it's also about punctuation. A memory from my early childhood, when I was 7 or 8, and it can be understood in English too, I think :

The mayor said the teacher is a fool.
VS :
The mayor, said the teacher, is a fool.

PS : We also have a rule :

A double sign of punctuation is preceded by a space ;
A single sign of punctuation is not preceded by a space.

I don't know if it's "cultural", but for me, it's easier to read.

Voyez ce que je veux dire ?...
See what I mean?...

 

[Bonsai Nut]

You mean phosphorus ?
N: Nitrogen
P: Phosphorus
K: Potassium

Pho... is before Pot... in alphabetical order. I could never remember, a friend gave me this mnemonic trick.
The percentage of K (Potassium) seems to be equivalent in both the mulch (1.1.4) and Jobe's fert (4.4.4).

And thanks for the links

No I mean Potassium (K). If you look at the study, the dry weight analysis shows the leaf mass contains 0.4% Potassium (average) by dry weight. If Jobe's (or another organic fertilizer) has a guarantee analysis of 4.0% Potassium, you would use 1/10 as much as if you used composted leaf mulch.

As my ex put it, it's like putting your plants on steroids.

Actually no... not really. A plant will only use a certain level of a nutrient, after which the rest will be washed away. In some cases, because some fertilizers are in the form of soluble salts, you may actually burn roots if you apply too much, or in too high of a concentration. This is definitely a case of where "more" is not always better.

However my point about leaf mulch was not that it is bad... just that it is really weak. If you end up having to put a cup of leaf mulch on your soil in order to provide the same amount of a nutrient as in two tablespoons of organic fertilizer, and all of that leaf mulch ends up choking your inorganic soil mix, it may not be the best approach.

 

[Frozentreehugger]

It is well understood that leaf mold is one of the best plant growing mediums there is .highly prized by the gardeners of the world . It is the main organic material in a forest floor .. it is made by composting leaves for at least 1 year rake leaves when there fresh fallen and add them alone to a composter . A little manure to start the process . When you have black looking earth that is spongy to squeeze together you have quality leaf mold .It can be sifted like anything else you put in bonsai soul . It can not be purchased in a bag or from a garden or landscape business or a city compost site . No matter how many bags of city housing ward waste bags of leaves they add to there compost pile . You have to make it yourself from fresh fallen leaves and nothing else . Oak is the best followed closely by maple . And it smells like the forest . According to the little old lady down the road that I share mine with for her potted roses .when the fines are sifted out it has uses in bonsai . For rich organic loving trees like Prunas And Malus and the like especially trees that will be reported frequently . It can be used as a organic component of bonsai soil I personally have never used at a higher rate than 25 percent of a mix . It does break down faster than composted vine bark for example but it’s not soil . I know people that have used it as a thin layer to promote moss to grow . On finished bonsai ( ultimate touch you can tell when moss is grown on instead of placed for a exhibition ) bonsai ) As for bugs and disease being present the risk is the same I think with composted pine bark . I would like very much for anyone that grows prunes Mume flowering apricot especially as a finished bonsai. To speak up as to what they use as a mix . My understanding is in Japan Apricot is grown . In normally 50 percent rich organic matter . Exactly what is often secret of each grower . And they are repotted every year . Leaf mild is not I repeat not a substitute for fertilizer in any way . It’s creme de La creme use most likely is a. Organic component in a refined old flowering tree . A rose expert told me it expands as it absorbs water holds more water per size than contracts as it releases the water this movement. Aerates the soil. Take the info as you wish