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Cinnamon is commonly used as an antibacterial/antifungal on houseplants. It’s *potentially* a great option because it’s cheap and, chances are, you already have some in your home.
But does cinnamon actually do anything for your houseplants?
There have been no scientific studies done on the effects of cinnamon on house plants.
There have been studies done on the antifungal properties of cinnamon, but they were done in a lab on yeast (you can read about here) with variable results.
I don’t use cinnamon on my houseplants any more.
I have used it in the past to reduce fungus gnat numbers, but whilst it did make a slight dent in numbers, it didn’t work nearly as well bottom watering my plants and making sure I have good airflow.
We only have anecdotal evidence for the benefits of cinnamon on house plants.
I didn’t see any results that made me think it was worth recommending it to anyone else BUT plenty of people have.
In short, give it a go if you fancy it, but don’t be surprised if all your houseplant problems remain unchanged.
Does it matter what type of cinnamon we use?
One of the reasons the pro-cinnamon brigade gives for cinnamon not working is that we’re using the wrong type of cinnamon.
There are a few different types of cinnamon, and apparently, if you’re not using the fancy one, you’re doing it wrong.
I'm beginning to wonder if this is all just a scam to get us all to buy fancy cinnamon. Is Big Cinnamon controlling us all?
Regular cinnamon, such as what you might have in your pantry as we speak, is cassia cinnamon, which is cheaper and not particularly beneficial to your health but because it tastes great and is cheap, that’s what we predominantly use.
Ceylon cinnamon is fancy cinnamon, and apparently, that’s the one that has all the anti-bacterial properties (but we only have a couple of inconclusive lab studies and zero studies on actually applying cinnamon to plants).
When you go to look, there's actually little difference in price between Cassia and Ceylon cinnamon - it's just that Cassia cinnamon is the one that's usually available. I don't really know why they're selling Cassia cinnamon if it's the same price as Ceylon but not as good for your health. I'm sure Big Cinnamon has their reasons.
So basically, neither type of cinnamon is likely to be of any benefit to your houseplants, but if you decide to try it anyway, then it’s Ceylon that you need.
Benefits of putting cinnamon on houseplants
As I said, there haven’t been any scientific studies conducted on the benefits of using cinnamon on houseplants.
This is indicative in itself that there are unlikely to be any benefits because if it worked, it would be used commercially (because it’s cheap and easy to get hold of).
However, if you're looking to try out cinnamon for yourself, here are some of the things that people claim it works for:
Can you use cinnamon as a rooting hormone?
You can try dipping the ends of nodes of your cuttings in cinnamon to get them to root faster. You’ll need to propagate them in soil or moss because water will just wash the cinnamon off.
Commercial rooting hormones contain synthetic versions of the plant's natural rooting hormones - that's why they work. There are no comparable compounds present in cinnamon, so they are highly unlikely to speed up the rooting process.
Some people claim that cinnamon stops cuttings from rotting so quickly due to its anti-bacterial properties. If you struggle with stopping your cuttings from rotting, I have an article here that will give you tips on preventing rot.
Is cinnamon an insect repellant for plants?
Some insects don’t like cinnamon.
Some people also say it deters cats.
For the sake of sprinkling cinnamon on the top of your soil, it’s worth trying BUT it’s unlikely to totally eradicate pests like fungus gnats.
If you want something you can use to top-dress soil to stop house plant pests, I highly recommend diatomaceous earth. Sand also works. Basically, the gnats can’t get through the layer because it’s so sharp.
Can cinnamon get rid of fungus on plants?
If you have a fungal issue with your plant, you’re better off getting a dedicated anti-fungal medication.
Cinnamon is highly unlikely to have much effect on a plant with a fungal infection.
That being said, there might be some benefits to using cinnamon as a preventative measure against fungus. Again, for the sake of sprinkling a bit of cinnamon on your house plants, it might be worth a go.
I personally have never had a plant with a fungal infection, so I won’t be trying it, but let me know if it works for you.
How often to use cinnamon on houseplants
If cinnamon is antifungal it *shouldn’t* go mouldy, so the only time you should need to replenish it is after you water.
Can cinnamon harm houseplants?
Probably not, unless you dump boatloads on them every day.
From my research, it seems that cinnamon is pretty neutral when used on house plants. It might convince the odd fungus gnat to go elsewhere, or stop fungus spores from proliferating (love that word) in your soil.
The effects of cinnamon on houseplants are likely to be a placebo/psychosomatic-type thing rather than actual science.
You can definitely try using it on the soil, but if you have real issues with your houseplants, cinnamon is unlikely to make a real difference.
It’s become a bit like apple cider vinegar – a cheap pantry staple that has some minor anti-bacterial properties so people exaggerate the effectiveness of it.