Willow Water Rooting Hormone – Does It Work?

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Robert Pavlis

Willow water rooting hormone is a simple DIY way to get some cheap rooting hormone. Lots of people use it for all kinds of cuttings and many claim that it works. In this post I will have a close look at the realities of willow water for rooting.

If you are not familiar with rooting hormones, have a look at this: Rooting Hormones – What Are They

Willow Water Rooting Hormone - Does It Work?
Willow Water Rooting Hormone – Does It Work?

Willows Root Easily

Take a piece of willow stem, stick it in the ground and it will root. A friend of mine wanted a rooted cutting from my corkscrew willow and I asked how big she wanted it. She said, “4-5 feet long”. I said, “that will never work”. Sure enough, I had no problem rooting it without any rooting hormone.

One reason it roots so easily is that it contains high levels of natural rooting hormones. It is basically a stick ready to root. One rooting hormone found in willows is indolebutyric acid (IBA), which is the main ingredient in many commercial rooting products.

Willows also contain salicylic acid (SA) which is similar to acetylsalicylic acid (ASA), the active ingredient in aspirin. Contrary to what many claim, this is not a rooting hormone, but it can help rooting hormones be more effective.

Microbe Science for Gardeners Book, by Robert Pavlis

Making Willow Rooting Hormone

There are numerous recipes on the internet for making willow rooting hormone, but they basically consist of taking various parts of a willow tree or shrub, crushing the material and steeping it in water. The IBA and SA leech into the water which can then be removed and used to root cuttings.

Some people leave the cutting in the water until it roots, and others just dip them for a few minutes before sticking them into rooting media.

It is claimed that the auxin IBA is most concentrated in new shoots and especially shoots harvested in late winter or early spring.

Most Cuttings Root Easily

The reality is that most cuttings that the average gardener tries, root easily without any rooting hormone. Many plants root in just water, and others in standard rooting media like sand or perlite.

A common claim for willow water rooting hormone is that it “is most effective on moderately easy-to-root plants”. But this kind of cutting does not need any rooting hormone!

More About Rooting Hormones: Rooting Hormone – Use Them Correctly

Limitations of Anecdotal Evidence

You will find two kinds of reports on the net. One type is mostly a DIY discussion of how to make and use willow water. They rarely provide any evidence or examples that show it works. The second kind of report discusses how it worked for a certain type of plant. These usually don’t provide details of how the water was made or which kind of willow was used.

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Neither of these reports are of much use to validate the effectiveness of willow water because they are not complete and because they rarely include controls. Without proper controls you can’t reach any conclusion.

Concentration of IBA in Willow Water

Willows contain IBA, but how much IBA ends up in a homemade willow water hormone solution?

It turns out that IBA is not very soluble in water, with a solubility of 250 ppm (at 20 °C). This is the highest concentration that you can get, assuming perfect extraction.

For herbaceous and softwood cuttings, commercial IBA rooting hormone is applied in concentrations of 500-1,500 ppm. Rates between 1,000 and 5,000 ppm are used for semi-hardwood cuttings and 10,000 ppm is used for hardwood cuttings.

Clearly, the amount of IBA in homemade willow water is significantly below the recommended levels. It might help for softwood cuttings, but will not be effective for semi-hardwood, or hardwood cuttings.

Many recipes recommend the dilution of willow water before use, which decreases its effectiveness even more.

IBA is more soluble in alcohol so it would be better to extract the hormone using an alcohol-water mixture, but nobody recommends this.

Concentration of IAA in Willow Water

IAA is also a naturally occurring rooting hormone found in willows. It has a higher solubility of 1,500 ppm, which would be high enough. IAA is not used in commercial products because it is not very stable.

Effects seen from willow water may be due to IAA.

Science on Willow Water

This study looked at rooting cannabis cuttings with two rooting gels; 0.2% IBA gel (EZ-GRO Inc.) and 0.2% willow extract rooting gel (EZ-GRO Inc.). The results show that the willow extract far under performed IBA in both the number of rooted cutting and the quality of cuttings. Unfortunately, a control with no rooting hormone was not done, so we don’t know if the willow extract was better than no hormone at all. Also note that (a) this was a commercial willow rooting gel, not DIY willow water and (b) it seems the company no longer sells this product.

A report looking at rooting apple cuttings found that willow water increased the number of rooted cuttings to 96%, but the control using only water had a 92% success rate.

Using willow water to water after applying standard rooting hormone resulted in more roots and longer roots using four different types of cuttings.

Olive cuttings can be difficult to root. When they are treated with IBA and followed with a soak in willow water, it was found that willow water made from the bark of weeping willow, did increase the rooting rate, but soaking in water made with wood, leaves or shoots had no effect.

Conclusion

There is limited science looking at the effectiveness of willow water, and what is there does not support the idea that it effectively initiates roots. It may contain low levels of hormone which might augment the natural hormones in cuttings and it may provide some benefits once rooting has started but the science suggests this effect is limited, if it is there at all. It is not a good rooting hormone.

I suspect the myth of willow water was born out of sound science; willows root easily and that they contain rooting hormones. From there, a leap of faith concluded that homemade willow water would work as a rooting hormone. This idea is then bolstered by gardeners who try it and claim it works, without ever running controls.

Given the lack of evidence that willow rooting water works, and the fact that it is not easily produced, it seems to make more sense to use commercial products that are easy to use, and are proven to work. For a few dollars you can buy enough rooting hormone powder to last 10 years or more.

 

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Robert Pavlis

I have been gardening my whole life and have a science background. Besides writing and speaking about gardening, I own and operate a 6 acre private garden called Aspen Grove Gardens which now has over 3,000 perennials, grasses, shrubs and trees. Yes--I am a plantaholic!

27 thoughts on “Willow Water Rooting Hormone – Does It Work?”

  1. Your article was very informative and I will continue to read them. This is not an argument and I certainly mean no disrespect. In your article you refer to trees. As only a hobby Gardner I don’t, or try not to purchase commercial packaged top soil or even potting soil. For a shorter read I try to “make my own dirt”. Trial and error way. No graphs, no measurements, watch nature, and follow it’s lead and of course common sense. I have found my vegetables, vine fruit, berries, flowers and flowering shrubs when first planted up to a mature level by using willow tea everything, roots and produces very well. However, continuing to use the willow water when the plant is trying to produce or bloom it seems the plant puts all of its effort into making more roots. But if I discontinue use of willow water when the plant is almost or mature it’s like ok I’ve got the this big deep healthy roots let’s make some produce. If I don’t use the willow water my plants are just, well so-so. Also another important thing to consider. Everybody’s water is different. When I say water, and gardening I’m talking straight from the well. The house water runs through a softener. How about rain water? Lake water. There’s people around me that go to the lake and pump water straight from the lake just to water their gardens. City water that smells like bleach. Just too many factors to consider. I’m not saying yea it works for everyone everywhere, but it certainly works for me. I can put almost anything clipping or seeds in a lightly covered tray spray daily with willow water and it will grow.
    I just wanted to pass this on.
    Thank you for the good read!
    Angie Dale,
    Hobby Gardner

    Reply
  2. I feel like your conclusion on apple propagation is skewed. I would like to offer you another viewpoint. An increase of 4% is huge. Let’s use a sample size of 100 for my opinion. For the price of nothing but 20 minutes of your time you have an extra 4 trees to sell. My local Lowe’s has apple tree starters, starting at 150 bucks apiece, just looked it up. That’s 600 bucks for 20 minutes of time. Not a bad way to spend 20 minutes. Now another to consider is if there’s a warranty on your product. As stated “Willow Water” aided in increasing roots development. Better developed roots would help minimize financial losses of replacement. If you were a small scale nursery, it wouldn’t just increase profit directly, but indirectly as well, through increased customer satisfaction and reputation of quality. If your boss comes to you and says hey i will give you an extra 4% raise. For an extra 20 minutes of your time at established intervals. Would you not take it? I freaking would, short lunch one day sounds too easy. In my means nothing opinion, youconclusion should be, does it work? Yea some data suggests on some things it’s better than nothing. Is it the best? Nah there’s plenty of higher concentrated, cost effective options on the market. Although might be something to consider for certain individuals in certain situations.

    Reply
    • Most gardeners only need another one or two plants – so a 4% is nothing.

      If you were in business doing this you would also not use a DIT solution with a 4% increase when a relatively cheap commercial product would do much better.

      Reply
  3. Robert, thank you for another very useful and thought provoking article, including links to valuable scientific papers.

    Reply
  4. Obviously Mr Pavlis is writing about something he has never tried. Homade willow water works fantastic when rooting cuttings. I chop up fresh green willow branches and boil them for a bit then let them sit overnite. Using willow water helps to create a massive root ball in my potted plants.

    Reply
    • Prove it to us.

      Show us a written description of what you have done. I want to see how you did the controls. How you measured root growth.

      Reply
  5. *Not trying to be rude in any way. I am merely trying to be exactly accurate. Furthermore, I must use quotation marks and “all caps” as substitutions for the more polite italics and underlining as I am unable to use either of the latter, my apologies.*

    To Robert Pavlis:

    In reference to the apple cuttings and Willow Water you provided:
    https://core.ac.uk/download/pdf/234662619.pdf

    If so, I think you may have unintentionally buried the lead; the benefit isn’t merely in increased “quantity” of the success rather the increased “quality” of those successes. With all due respect, you cherry-picked and misrepresented the data to reinforce your “myth busting” viewpoint. I normally enjoy reading your work but I do not understand how this study was proof of anything other than Willow Water works well. You behave as if the only reason anybody would use Willow Water is to increase the quantity of successful cuttings while ignoring every other benefit. Furthermore, you misunderstood and misrepresented the only data you deemed worthy to share.
    First, you did not parse the sprouting percentage numbers accurately and exposed your misunderstanding by downplaying it’s significance. While the maximum increase in “roots” vs “no roots” is “only” 5.476% from Willow Water, this is the smallest opportunity for variance in hard numbers in the study as the “floor” begins at 91.707 of 100 while all the data you chose to ignore has no limit. A more accurate way to understand this would be: in only 8 hours of exposure to Willow Water, apple cuttings reduce their failure to root by over 66.032%.
    Second, you ignored the rest of the data that shows you did not disprove this “myth”. In only 8 hours of exposure to Willow Water the plant is 97.002% taller, has 174.199% more roots, the roots are 112.789% longer, the diameter increased by an astounding 721.8356%, and the number of primary branches increased by 139.785%. You ignored or hid all of this data behind a poorly rounded 4% increase.

    What concerns me is how deeply wrong you were and the arrogance required to misuse data to arrive at a conclusion opposite that of the data. The paper you used to prove Willow Water is a “myth” proves the opposite, Willow Water works, that you fundamentally do not understand how to parse scientific studies, that you misunderstand simple mathematical concepts like percentages, and that you look only for the data that reinforces your worldview while ignoring data that directly refutes it.

    However you feel about this situation, you fundamentally misunderstood and misrepresented data from a mildly authoritative position that it doesn’t appear you have the patience and understanding to occupy. But don’t feel bad, the paper had a typo too, even a group of doctors didn’t get it perfect on their final draft. I apologize if my normal bluntness comes across too harshly; I mean nothing more than I say and wish you well in all of your life’s endeavors.

    Willow Water Math:

    Sprouting Percentage and Misunderstanding
    100%-91.707%=8.293%
    5.476%/8.293%≈66.032%
    Height
    20.567cm/10.440cm≈197.002%
    # of roots
    14.093/5.620≈250.765% (Their paper has a typo.)
    15.410/5.620≈274.199% (Using their chart data)
    Length of Roots
    14.093cm/6.623cm≈212.789%
    Plant Diameter
    1.3700cm/0.1667cm≈821.8356%
    # of primary branches
    5.1633/2.1533=239.785%

    Thank you for your time,

    DK

    Reply
    • I have no idea what you are ranting about. What I said was “A report looking at rooting apple cuttings found that willow water increased the number of rooted cuttings to 96%, but the control using only water had a 92% success rate.”

      Those two numbers are taken directly from Table 1 – they are the numbers presented in the study. No calculation needed.

      Reply
      • What he is ranting about (did you read his post?) is the willow water is effective for the purposes of rooting in that it positively affects all aspects of it.

        These are some excerpts from the study:
        “The mean data revealed that there is a significant effect on apple cutting after treatment with the willow extract.”
        “… willow extract has a significant effect on the number of root per plant.”
        “… the root length was significantly effected by the treatment of cuttings with the willow extract. ”
        “… a significant effect of willow extract treatment was found on the plant diameter. ”
        “… the number of branches per plant was significantly effected by the treatment of cuttings with the willow extract. ”

        “Significant effect” on much more categories than simply rooting, which is the only thing you were concerned with in this article. Applying willow extract resulted in a better plant, not just a binary ‘rooted or not’ result. Even if it did not increase the rate of rooting at all, it would still be worthwhile to use it.

        This is like saying plant A and B are equal because they both bore fruit, even though plant B produced 3 times more of a higher quality fruit.

        Reply
        • Who is “he” ?

          This post asks the question do alternative solutions work to root cuttings. It does not look at the quality of the roots produced.

          The study you are referring to found a slight increase in rooting, and I reported that in “A report looking at rooting apple cuttings found that willow water increased the number of rooted cuttings to 96%, but the control using only water had a 92% success rate.”

          In my books a 4% increase, on a cutting that roots so easily, does not convince me to try it.

          Reply
    • I have willow trees around my pond. I did a side by side test with potted plants to see if willow water works to improve root mass. It most certainly does and it is not a myth! People will write anything to sell a book.

      Reply
      • 1) You missed the whole point of this post – it is not talking about growing roots on potted plants. So your so-called test is useless to answer the question being asked because you used “potted plants”.

        2) If you actually read the post you would know that what I said was “There is limited science looking at the effectiveness of willow water, and what is there does not support the idea that it effectively initiates roots. It may contain low levels of hormone which might augment the natural hormones in cuttings and it may provide some benefits once rooting has started but the science suggests this effect is limited, if it is there at all. It is not a good rooting hormone.” I never said it won’t grow roots.

        So provide some scientific data to support your position?

        Reply
    • Thank you for the link to the paper.
      The paper is very interesting, and may be useful in our growing apple trees from cuttings.

      Reply
  6. Do Elderberry cuttings require a rooting hormone, or do they root easily in water alone? I will be receiving mine in the mail soon and I prefer to not use a synthetic product on my edible plants, as I prefer organic gardening. Do you have any recommendations if a rooting hormone is needed?

    Reply
    • That is a good question. I tried to find a definitive answer to this question without much luck. If it is kep dry, and away from sun, I suspect it lasts for years. This is what I wrote before:

      “For the average gardener, a bottle of rooting hormone is enough to last a lifetime. That sounds like a good deal. Unfortunately, the hormone has a expiration date. Some manufacturers suggest it should be discarded after 1 year. Some say it is good for two years. Hormex says this about their product, “As long as Hormex Products are kept at room temperature and out of direct sunlight, the shelf life is 3-4 years”. Chemical companies report that IBA is very stable suggesting it will last many years. No one seems to provide any real proof of how quickly it degrades. A lot of drugs are good well past their expiration date.

      Solid chemicals (ie powders) are generally more stable than diluted chemicals, so powders probably last longer. I suspect the powder forms have a shelf life of at least 5 years and probably more than 10.”

      From: https://www.gardenfundamentals.com/use-rooting-hormone-correctly/

      Reply
  7. Just an aside – I had, at one time, a passion fruit vine. My wife fixed up an arrangement that I took to work. Numerous people asked for starts so I agreed to try and get some. I experimented with liquid vitamin B, put 12 hoot in plain water with zero success. Put the same number in the B water and every one rooted. Have not tried any other cuttings in that manner. I normally use a powder rooting compound and have enough success that I continue doing fuchsia cuttings, princes flower, Mexican firecracker, daphne odora, oak leaf hydrangea and others. I do not do it commercially – no time for that but enjoy sharing with family and friends.

    Bob Boysen

    Query I do have a pretty fuchsia, the name of which I do not know. Do you have any suggestions as to where I might send a photo and hope to get it identified? There was a local nursery called Fry Road nursery that was very helpful with this sort of thing but they are no longer in business. I’ve tried a couple of local nurseries without success. I would appreciate any help you miht be able to give in this regard.

    Thank you,

    Bob Boysen

    Reply
  8. So what do we use when we don’t have commercial products available? And was willow used back in the day when that was the case? What is a good reference benchmark for rooting woody plants of three classes in sand or just water: percent rooted?
    I have found for instance that black currants are very simple to root, 9 of 10 specimens do so in water.
    Old 99 Farm, Copetown

    Reply
    • I don’t think there is a good benchmark plant.

      If you have access to commercial products, I would suggest making willow extracts using alcohol to try and get hormone concentrations up.

      Reply
    • Dirr and Heuser’s “Reference Manual of Woody Plant Propagation” (2d edition, 2006) says Photinia is a recognized benchmark, because spontaneous rooting is very, very low.

      Reply
  9. What I’ve heard of – haven’t tried it – is putting Willow shoots in the same water as the to-be-rooted cutting, so the hormones are leached into the water as the Willows themselves root.

    Reply

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