Banana peels are great for your plants, or at least that is what the internet says. You should bury some peels in the bottom of the hole when planting roses. You can add them to water and let them sit for a few days to make banana peel tea, an excellent fertilizer for indoor plants. Try drying them into a black leather and then crushing them to make banana skin powder which is great for the garden. I even found one web page that makes a fertilizer spray out of them.
Eating banana peels is also a hot topic and they reportedly provide all kinds of health benefits and even whiten teeth.
Lets have a look at the reality of banana peels for plants. Are they better than just another source of organic matter?
Banana Peels for Plants – The Claims
I started this post when I saw a YouTube video that claimed banana peels have an NPK of 0-25-42.
When you see claims like this it is critical that you give them a quick sniff test for reality. Does it make sense? Does it seem realistic? If not – run for the hills because the rest of the advice is now suspect.
A banana peel is part of a plant. A plant needs protein to function – all living organisms have this requirement, and protein contains nitrogen. Clearly the number zero for nitrogen is complete nonsense. No living organism, including all plant material has a nitrogen level of zero.
All living organisms contain water, and in fact they contain a lot of water. You probably know humans are mostly water and so are plants. This number is around 80%. If a banana is 80% water, how can the potassium level be 42%?
Even if you didn’t know the 80% moisture value, the above NPK number says that 67%, or 1/3 of a banana peel is phosphate and potash. Does that make any sense at all? NO!
This is not the only site that claimed a 42% potassium level, which is completely ridiculous.
The Question to Ask
All organic matter is good for soil and plants. They all provide a carbon source and plant nutrients as the organic matter decomposes.
The important question is, are banana peels significantly more nutritious than other sources of organic matter. Do they provide any unique beneficial chemicals? If they do, they might be a superfood for plants.
Vague Claims for Banana Peels
Do a bit of Googling and you quickly find all kinds of claims saying banana peels have a “high” nutritional value. Some even say the peel has higher nutrients than the banana. This sounds convincing, but you may have noticed that there are no numbers included in these statements.
What does “high’ mean? And how much higher is it compared to other organic matter? Without numbers, these are just fancy words to try and convince you to believe a story.
Dry or Wet Weight?
Even when numbers are supplied, there is still a big problem with the data. Is this based on wet weight or dry weight? When someone says a banana peel is 42% potassium, is that based on a normal wet peel or a dry peel? This is a crucial point since most of a banana peel is water.
Chemists get around this problem by reporting chemical content on a dry weight basis. But many sources take these numbers, if they even bother to look it up, and present them as a wet weight, which exaggerates the value by a huge amount.
Chemical Analysis of Banana Peels
Several nutritional experts made the claim that banana peels have not been studied for nutrients, but I had no problem finding some studies.
Note: Except for the moisture values, all percent values are based on dry weights.
Sources: Source A, Source B, Source C, Source D
The average nitrogen in protein is 16%, so the 3.5% protein in banana skins is equivalent to 0.6% nitrogen.
The above table reports values for potassium and phosphorus, but NPK uses values as potash and phosphate. The potash and phosphate in banana peels is 11.5% and 0.4%.
The NPK value for banana skins is 0.6-0.4-11.5. But this is the value for dried banana skins since all of the above values are calculated on a dry weight basis. The NPK of fresh banana peels is 1/5 of that, making an NPK of 0.1-0.1-2.3.
For comparison, purchased bagged manure is around 1-1-1.
Are Bananas High in Potassium?
Not really. Bananas have more potassium than some other food, like grains and meat, but all fruits and vegetables are higher in potassium – “there is nothing special about bananas. Tomatoes, potatoes, and beets also have potassium and often more potassium than your average banana.”
One cup of chocolate milk contains the same amount of potassium as a banana.
Magical Properties of Banana Peels
There are also some vague claims of other important chemicals in banana peels that might be beneficial to plants, but I found no specific claims that could be reviewed.
There are many more claims for our health, including things like antioxidants, but a cursory look shows that the science is not there for the benefit of these, at least not yet.
Banana peels are just another source of plant organic matter.
Banana Peel Tea
Some claim you can steep banana peels in water, either using hot water, or just letting them sit for several days in the sun.
I have reviewed the value of using left over tea before and this tea would be no different. There is limited decomposition during the process of making it, which means that most of the nutrients remain in the peels.
Potassium leaches out of organic matter more quickly since it is not chemically bound, and banana peels have a higher level of potassium, so the tea might add some potassium, but not much else.
Don’t get conned by tea claims for plants.
Banana Peels for Roses
This is a very common piece of advice. Place some banana peels in the hole before you plant roses. Some even take the time to cut them into small pieces.
Why just roses? If this was good advice, would it not be good advice for all plants? Or is just that roses love bananas – or is that garlic?
As banana peels compost, they turn into black mush. I just can’t see this being good for new tender roots?
Look at the NPK. It is very high in potassium relative to nitrogen and phosphate. That is not an ideal ratio for plants. To compensate for this some people add eggshells! We know eggshells don’t decompose in most soil, and how would adding calcium balance the problem?
This idea probably started because people believe bananas have a high potassium level, and we have the very common myth, that potassium stimulates roots – which it doesn’t. From this misinformation it naturally follows that banana peels stimulate roots and flowers on roses?
This is just a dumb idea.
Bury Them Around Plants
If you forget to add them to the planting hole you can dig up the soil around the roses, add the peels, and cover them with soil. Roots grow in the top few inches of soil – digging around the base of shrubs is never a good idea.
What Should You Do With Banana Peels?
Banana peels may contain a psychoactive substance, and smoking them may produce a “high”, or a sense of relaxation. This may be a myth associated with the 1966 song “Mellow Yellow” by Donovan.
Apparently, some people even eat them as a cooked desert or a smoothie drink, and that is OK. A vegan food blogger’s recipe uses banana peel as a ‘pulled pork substitute’ – I don’t think so!
Banana peels are just another form of plant-based organic matter. Add them to the compost pile, or spread them on the ground to decompose. They will add value to both the soil and plants but they are not a superfood.
Don’t get hooked in by all the crazy ideas on the internet.
The only way I see banana tea even having a chance of really working is giving it lots of time to break down completely or at least almost completely. It’s silly to think that a couple of days in water and it becomes some miracle tea. If that was the case then we would be growing bananas and making banana teas for field crops. 5 minutes of just thinking about it and tells you that it’s BS.
To bad most people don’t take a few minutes of thought – yes it is quite obvious.
You probably know humans are mostly water and so are plants. This number is around 80%. If a banana is 80% water, how can the potassium level be 42%?
😂😂😂 yes 80% for a newborn baby, you on the other hand will have about 55-60%
Doesn’t matter what anyone has to say, we’re automatically wrong🙄 Even though this has worked for many…yes, even with one pot receiving it, and the one next to it NOT receiving it. I’m sure he’d say it was just the individual genes of the plants themselves 🙄 He obviously has some miracle fertilizer of his own that he’s probably selling 😂
Or he is looking for scientific proof, rather than anecdotal proof without any measurements or controls?
Linda has apparently performed a statistical trial with sample size = 1, plus 1 control. Next step – do a field trial with a large sample size and large number of controls.
Thanks for this article. Very perfect.i will share it with my community.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9122687/?fbclid=IwAR19HV-aIeyGAtW7ZGdF31NIHNLiNi1CBxAhzKobnM2-7j5j_Z23KpiR8nA
Use of banana peels within 6-10 inches of the surface has been highly effective in my gardens where I used earthworms and net neutral in the gardens without them. My unscientific theory is that decomposing banana peels attract worms to a specific location bringing nutrients and burrowing areas for easier root growth. The results are good enough for me in the Southern US to keep doing it in my beds that have earthworms.
1) You presented no data to show it was “highly effective”.
2) Yes – decomposing organic matter will attract worms – the post is not about that. But banana peels are no better than other organic matter.
My plants tells me that they love the banana peel tea by producing good leaves..
Without doing controls you do not know that plants love it – they could have grown the same good leaves without it.
Robert, there are some practices that work wonders on plants that have no scientific explanation, yet. Gardeners have been using certain pest control practices ( ex. marigolds) for years. It works. The certified lab only provides the percentages (NPK). The lab does not tell you how the plant absorbs it. Like humans, plants have preferences.
1) Gardeners only think these practices work. For example, marigolds don’t work for keeping pests away – they actually increase the number of pest.
2) “The lab does not tell you how the plant absorbs it.” – actually research has provided a huge amount of material that describes this.
3) ” Like humans, plants have preferences” – no. Humans have preferences based on taste and pleasure. Plants do neither of these. All plants need about the same amount of nutrients and use them for the same reason. The differences between plants is minor. I don’t eat brussels sprouts, but you will never find a plant that does not absorb nitrogen.
Of course why certain practices “work wonders” in the garden mythosphere, while they don’t give significant differences in controlled trials, is also a subject worthy of study.
Hello, Robert, I was reading your article while chopping up my banana peels and preparing to seep them in water with other scraps in order to add them to my houseplants. Your scientific scepticism has inspired me to regoogle my plan and I’ve ran into https://thrivingyard.com/blender-composting/
What do you think about this? If the scraps are added as a smoothie to the pots, all the nutrients should end up in the soil, decompose and end up available for the plants to enjoy. I have no scientific evidence to back up this claim.
It is a joke! All this makes is blended kitchen scraps. There is zero composting taking place until after you pour it into the soil.
I like, “I tend to study academic papers when I’m looking for evidence to support the wacky ideas” – they clearly did not do this before they wrote this post.
Eventually, the stuff will decompose. Do you want a compost pile on your plants?
Okay…..
Plenty of nutrients can be obtained from banana peels through boiling. Using an electric tea kettle you can boil them over and over, 3 or 4 times all within a half hour apart. Within 2 hours you’ll have the tea, It’ll be concentrated, not just “Color water”….Once it cools off, dilute accordingly, add to a spray bottle. You now have a foliar spray with extra potassium and pretty much no nitrogen. I realize there are alternatives, miracle grow liquid plant food is just fine. Blah blah, I’m not disputing that, just making it clear that boiling actually makes these peels useful.
“Plenty of nutrients can be obtained from banana peels through boiling” – where is your proof that this statement is true??
Dilute accordingly. That’s a vague statement that means absolutely nothing. What is accordingly? 1:1, 1:100, 1:1000 …. Just what is it?
The thing is bananas are no better or worse than any other organic matter. No one knows the dilution because the mother liquor isn’t analysed …. And foliar feeds don’t contribute a lot of nutrients because they aren’t translocated within the plant.
Correct, although we can even make concentrates if we do it correctly. To correctly make a fertilizer from plant matter like banana peels, all that matter has to be boiled for at least an hour and not just stay in water for days, like the internet says. No composting is required either. After boiling, filter it and throw away the matter and keep the water. That (completely clear from alive microbes and pathogens) water is going to have almost all the nutrients from the boiled matter, in a concentrated and sterile form.
Prove to me that a 1 hr boil releases almost all the nutrients.
That’s why I said “at least”. Obviously, for “almost all” nutrients it needs to be boiled for way too long, which also is going to be affected by many other factors. My comment was to remind that it is very possible to gather nutrients in concentrated form any plant matter by boiling, although that would require further testing and analysis to be sure about the exact contents and amounts/ratios of the chemical substances in the extracts. An hour of boiling can release a great amount of nutrients into the water, in comparison to the illogical “just leave it in water for some days” thing that does nothing. The advantages in what I said are highly notable. Also, there’s no safest fertilizer than a sterile one. With some chemistry, these types of boiled extracts can even used to separate specific molecules.
“An hour of boiling can release a great amount of nutrients into the water” – how do you know that? Do you have some science to back up that claim? And how do you define “great amount”?
I suppose you don’t drink teas, and how, for example, its antioxidants, caffeine etc enter the water that eventually becomes the tea. It’s simple decoction. https://en.wikipedia.org/wiki/Decoction
“Great amount” is in comparison to the main topic of the article, I defined it as much greater than the outcome of a simple infusion in water, that yields traces (if any).
Most interesting and the comments.
I’ve gardened for many years and chopped up banana peels and thrown them around plants. Other gardeners regardless of the said science using only banana water/tea have high yield.
Ask any Asian gardener what they use and banana peel is definitely used.
In passing & on FB a well-known successful group of organic growers, whereby a lady uses only the water / tea and her basil and herbs grew twice the size as opposed to using other fertilizers.
Wives tales? We may well ponder!
1) Soil that naturally contains all the required nutrients will grow good crops even if you do not fertilize. So adding anything extra will also grow good crops.
2) A statement like ” X tea grows bigger crops than fertilizer” is wrong. It is not chemically possible. Plants grow from nutrients. If you add nutrients it makes plants grow – the source does not matter. Statements like this come from people who either do not make controls, or don’t know how to make a proper control.
Right, I get thr point that the reference of 42% Potassium is incorrect and that fertilizer tea is in most (or all) cases a waste of time and effort. Ok it is not a “superfood” either (whatever that means anyway). HOWEVER my aim is it to find ways of fertilizing my garden without the fertilizers you buy in the farmshops and therefore your article and explanations have still convinced me that Banana peels are (amongst others) a good source for “natural” fertilizer by urilizing leftover plant material – especially since I grow my own banananas. So to me it still makes sense to somehow use them knowing I can give my plants a little extra boost without wasting my money in the farmshop.
Nothing wrong with using them as long as you understand it is just organic matter – not super organic matter.