What is the best rooting hormone for plant cuttings? Numerous homemade remedies are claimed to work for rooting cuttings, including cinnamon, honey, willow extracts, aspirin, peroxide, coconut water, vitamin C and Aloe vera. Which of these work best?
How do they compare to commercial products? In this post I will review various options promoted on social media and recommend the best ones.
Antifungal vs Rooting
These two concepts are commonly misunderstood in discussions about rooting cuttings. There are two processes to consider when trying to root cuttings. The main one is to get the cutting to initiate roots and this can only be done by having enough rooting hormone in the plant. It can be natural rooting hormone, or it can be added by the gardener.
The second process is keeping the cutting free of fungal attack so that roots can form. If cuttings get infected before roots form, the cutting may deteriorate to a point where roots won’t form. In this way antifungal agents may help rooting, but they don’t actually cause roots to form.
If cuttings are kept relatively clean, fungal infection is usually not a problem and for this reason most commercial rooting hormones do not contain a fungicide.
Cuttings that have been taken incorrectly, or at the wrong time, or from plants that are hard to root, tend not to root. Consequently, they develop a fungal infection as the plant material dies.
Cuttings Root On Their Own
Many cuttings root on their own without any added rooting hormone because cuttings naturally contain it. Most softwood cuttings from herbaceous plants and houseplants root very easily. Most shrubs are easily propagated from softwood or semi-hardwood cuttings.
This fact has led to a lot of confusion about homemade rooting hormones. Place some aspirin in water, insert the cutting and it roots. People incorrectly conclude that the aspirin caused the rooting. It didn’t. The water, along with the natural rooting hormones in the plant caused the cutting to root.
To test a rooting hormone, you need to use a plant species that does not root easily and you need to run controls by trying some cuttings with and without the test material. Without a control you can’t claim success with any homemade rooting hormone.
Honey Rooting Hormone
Honey contains no rooting hormones so it will not help cuttings produce roots. Cuttings of Queen of Philippines (Mussaenda philippica), showed no improvement over controls. Honey also did not significantly increase rooting on Parkia biglobosa. There was some improvement in rooting when pre-soaked in honey before IBM (a rooting hormone) is applied, for Ricinodendron heudelotti.
A few online citizen science projects compare honey to a control or a rooting hormone. These usually show that both the control and honey work, but they don’t have enough samples and repetitions to reach any statistical conclusion.
It does have antifungal properties and may reduce fungal infections, but as stated above this is usually not a problem with healthy cuttings.
The reason honey does not spoil is that it only contains 17% water. At this low level, it sucks the water out of bacteria and fungi, killing them. I can only assume that dipping a cutting in whole honey would do the same to the cutting and harm it. Many people suggest a honey solution, which would be better.
Cinnamon Rooting Hormone
We talk about cinnamon as being one product, but in fact it is many, and the so-called cinnamon available from grocery stores in North America is not even the real cinnamon. Anecdotal comments about cinnamon working are of little use since they never specify which cinnamon is being used.
Cinnamon, real or fake, does not contain rooting hormones. It does have some antimicrobial properties and may help keep fungal growth down, but it does not cause roots to form.
Coconut Water Rooting Hormone
Fresh coconut water contains growth hormones and regulators; after all a coconut is a seed. These chemicals are very unstable and variable. Some have suggested that coconut water might work as a rooting hormone but few tests have been done.
In one test, fresh green coconuts were used but there was no increase in rooting. Another study using semi-hardwood cuttings found more rooting with coconut milk but the study does not provide details of the milk used, nor does it provide adequate statistical analysis.
Coconut water from fresh green coconuts may contain rooting hormone, and may work as a rooting hormone, but this is not a common source of coconut milk for most gardeners. It is unlikely that coconut water from a jar or can will work.
Peroxide Rooting Hormone
Peroxide is a common name for hydrogen peroxide, that is normally supplied as a 3% solution. Higher concentrations are available.
Hydrogen peroxide is a disinfectant and contains no rooting hormone. It is a signalling molecule in a wide range of reactions during plant growth so its presence may improve the normal rooting process.
Peroxide produced quicker rooting in semi-hardwood olive cuttings (which are hard to root) when it was used as a pretreatment before applying IBA rooting hormone. There is also evidence that peroxide is involved in the function of IBA in mung bean seedlings and that it helps with root growth in sweet potato seedlings.
A simple citizen science experiment compared cuttings in water with and without hydrogen peroxide. Rooting only occurred without peroxide.
There may be some value in treating cuttings with peroxide before applying rooting hormones, but there is no evidence that hydrogen peroxide on its own causes roots to develop.
Aspirin Rooting Hormone
Aspirin is not a rooting hormone and it probably has limited if any positive effect on rooting. For more on this see, Aspirin Rooting Hormone – Does it Work?
Willow Water Rooting Hormone
I have discussed this option in detail in another post called; Willow Water Rooting Hormone – Does It Work?
Willows contain natural IBA and so it is claimed by soaking the bark, you create a solution of IBA that will work as a rooting hormone. The problem is that the solubility of IBA is low in water and even if the extraction is as complete as possible, the resulting solution is lower than any recommended commercial product. Not only that, but most recipes suggest diluting this, which makes it even less effective.
The concentration of IAA may be high enough but the science does not support the idea that willow water is a good rooting hormone solution.
Other Homemade Rooting Hormones
There are a number of other homemade rooting hormones that are promoted on social media, but they are not taken seriously by most people and they probably don’t work. These include:
- Aloe vera juice
- Vitamin C
- Apple cider vinegar
If you disagree, post a link to a scientific study in the comments below.
What Should Gardeners Do?
Many plants root easily without any rooting hormone. If you do not have a commercial product, try rooting the cutting without it.
If you plan to do more difficult cuttings, buy a commercial powder. It will last at least 10 years and be worth the money. Fooling around with home remedies that either don’t work, or don’t work very well is not worth your time.