Potassium from Fruit Skins

enoughcliches(Tropical)February 24, 2007

I have been looking for a good organic source of potassium (things like greensand and kelp meal are not available here).

Referring to the useful table at


I notice that many of the best sources of potash are fruit/vegetable skins *but* only their "ashed" forms are listed. Does the burning process actually change the potassium content, and if so, by how much? If I were to just bury fresh skins under my leaf mulches, how long would it take for the soil to be ammended in K by an appreciable amount?

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gardenlen(s/e qld aust)

we ahve always been told that banana skins are very good nothing about burning them though, reckon the whole banana would be just as good as they are supposed to be high on potassium.


Here is a link that might be useful: len's garden page

    Bookmark   February 24, 2007 at 3:14PM
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Thanks, gardenlen. Does the potassium get supplied as fast as the banana skin decomposes, or is there some other process involved before it becomes readily available to the plants?

    Bookmark   February 24, 2007 at 9:44PM
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Sometimes the only way to determine the minerals in some materials is to burn off the rest of the material and measure what is left and this is what the "ashed forms" mean. All vegetables and fruits have relatively large amounts of potassium, and phosphorus as well as numerous other nutrients, which the bacteria in a good, healthy soil will make available to the plants growing in that soil. However, if you do not have a goo active Soil Food Web adding fruits or vegetables will do little until that Soil Food Web is active.

    Bookmark   February 25, 2007 at 6:20AM
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gardenlen(s/e qld aust)

not sure about how fast it becomes available they do break down fairly quickly, the organic tomato growers over here say to put a banana skin under each tomato plant as you plant them out, what nutrients are or become available to plants after we put compostable/rottable material into our gardens largely depends on the earth worms and the micro system ie.,. bacteria etc.,. to break those elements down and make it availble in a simple form where plants can absorb it.

so the way i see it we gardeners feed the soil and if we get that right the soil feeds the plants. our only indicator to soil health in a natural way is our earthworm populations i reckon. outside of that we don't worry too much and our plants are healthy and produce well.


    Bookmark   February 25, 2007 at 2:26PM
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I always assume that fruit skins, particularly bananas (which I eat daily) do their best work in my compost pile. That's also where I put my egg shells. I crush and save them all winter in the freezer. The banana peels I just dump on the pile, unless there's too much snow. BTW, it doesn't work too well with citrus peels. They take too long to break down.

    Bookmark   February 25, 2007 at 7:09PM
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In regard to using the eggshells, organicburro, do you clean the egg white off of the shells before you store them, or not?


    Bookmark   February 25, 2007 at 8:15PM
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gardenlen(s/e qld aust)

g'day organicburro,

in the heap/pile or bin/tumbler or as we do we have cut out the middle man so to speak we put all our rottable scraps direct daily to the garden just pull back the mulch and lay it on top then recover with the mulch.

the worms and i'd guess the other micro-organisms seem to be loving it that way? as our growing medium is performing well as the plants are healthy and producing well. reckon the best worm farm is where it will do the most good in the garden bed.


Here is a link that might be useful: len's garden page

    Bookmark   February 26, 2007 at 1:38PM
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Len, I had heard the same thing for roses - put the banana in the soil and then plant the rose.

However, I use my rotten bananas for the butterflies that don't nectar on flowers, but rather rotting fruit, dung, and tree sap. These include the emperors, Mourning Cloaks, and anglewings.


    Bookmark   February 26, 2007 at 8:39PM
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Composting is great, but I think there is something not usually understood.

Plants use nutrients only in water soluble form.

Organic matter is rich in nutrients not in water soluble form, but those nutrients are turned into water soluble forms as they break down (as in a compost pile).

While compost is rich in nutrients not presently in water soluble form, many of the nutrients in a compost pile do become water soluble before the compost is finished and they leach away with the rains/irrigation.

For this reason if one's desire is to feed plants organically it makes more sense to compost in place than have a dedicated compost pile. This way all the nutrients work their way to the plant's root zone.

Compost piles are great and I mean to say nothing against them (got one myself) other than many of the nutrients will leach away before the compost is finished and used.

    Bookmark   February 26, 2007 at 9:59PM
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The only reason any nutrients would "leach" out of a compost pile is if it is kept too wet. If the compost pile is held, fairly dry, for months there wil be no loss of nutrients. No water flow through the pile means nothing is being removed.

    Bookmark   February 27, 2007 at 7:32AM
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captaincompostal(z7 AL Bham)

Dry molasses is another great source of potassium, and about 20 more micronutrients. It is also a super great biostimulant for composting and soil building.

    Bookmark   February 27, 2007 at 7:54AM
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steveandjoy(z10 BGI)

What I tend to do is blend my banana peels in a blender with some garlic and water and apply to potassium loving plants, especially roses. I dig a little hole and just pour it in.


    Bookmark   February 28, 2007 at 2:57AM
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Joy, can you use just the banana after it has gotten really soft? My blender is a cheapo and doubt it would actually "blend" the peels. I do have a food processor and it probably would work better. Also, what is your ratio of banana peels to garlic to water. I am assuming you break down the bulb into cloves of garlic?


    Bookmark   February 28, 2007 at 7:01PM
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led_zep_rules(5 WI)

I don't do all that extra work of blending things for my garden. Besides composting, I often will put large quantities of rotting bananas directly into my garden soil when mucking about with it for some other reason. (I get free old produce sometimes, it wouldn't be practical to blend 7 cases of bananas!) A few months later there is never any sign of the bananas except for the hard bits of the stalk at the top end of the peel. That is if the banana/peel is buried. It will dry out and rot more slowly if left on top of the soil.

I have acidic soil, so also sprinkle a small amount of wood ashes from my woodstove in my garden. That has a lot of potassium, 6-8% typically, and even more calcium, plus a little phosphorus, and no nitrogen. It also raises the pH, so if you have alkaline soil to start with, don't apply ashes. Also, ONLY use ash from plain firewood, not treated lumber or charcoal or coal or anything that isn't just wood. So if you know someone with a wood stove, ask for some ashes.


    Bookmark   March 1, 2007 at 12:47AM
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steveandjoy(z10 BGI)

susanlynne48, It's just the peels that my family leaves behind after consuming the fruit. I may put about 2 banana peels into the blender and throw in a few cloves of garlic. Then I blend with water and continue to blend it until the wate reaches the top. I guess it's not really necessary, but my 3-yr old son and I enjoy making banana garlic smoothies for the roses.

    Bookmark   March 1, 2007 at 8:40PM
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