Willow Extract Is Natural Garden Rooting Hormone, But The Question Of Whether It Works Often Leads To More Myth Than Practical Advice. This Guide Explores What The Science Says, How To Use Willow Extract Effectively, And When It’s Best To Rely On Synthetic Alternatives.
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Willow extract is sometimes used as a rooting hormone. Some people swear by it. But others debate its effectiveness. This guide examines the science behind it, how to use it properly, and when synthetic options may be better.
What Is Willow Extract (Willow Water)?
Willow water is a natural solution made by soaking the young branches of any willow tree (genus Salix) in water to extract its active compounds. But note, Salix alba, Salix babylonica, S. cortex and S. viminalis are the species most tested.
Active Compounds: Its rooting power is due to two main ingredients:
Indole-3-acetic Acid (IAA): A natural auxin (plant hormone) that directly stimulates root growth. This is the same active ingredient found in many commercial synthetic rooting products.
Salicylic Acid (SA): A natural plant defence compound that helps protect the soft tissue of cuttings from fungal rot and disease.
EU Regulatory Status: Willow bark extract is approved as a ‘basic substance’ under EU and UK agricultural regulations, currently authorised for use as a fungicide in arboriculture and viticulture.
📊 What the Science Says: A Summary of Key Research
Scientific studies have directly tested willow extract against synthetic rooting hormones and untreated controls. The results show its potential is highly dependent on the plant species.
Plant Species
Willow Extract Efficacy
Compared to Synthetic Hormone?
Key Finding
Thornless Blackberry
Effective
No
Willow extract achieved a 66.7% rooting success rate when the shoots were collected in January. The efficacy varied significantly depending on the time of year the willow was harvested.
Chrysanthemum & Lavender
Effective
No
Willow bark extract was confirmed as an effective biostimulant, speeding up the propagation of these ornamental plants.
Cuttings treated with willow extract rooted consistently better than those in untreated water (the control group).
Snowbush (Breynia disticha)
Mixed
Yes
While synthetic hormones produced the highest number of roots, the roots were short and had few side branches. Willow extract produced longer roots with more secondary branching.
Petunia
Less Effective
Yes
Synthetic IBA (500 ppm) was significantly more effective for survival rate and root characteristics than willow water extract.
Cannabis
Less Effective
Yes
In a direct comparison, 0.2% IBA rooting gel delivered a 2.1× higher rooting success rate and 1.6× higher root quality than a 0.2% willow extract gel.
How to Make & Use Willow Water for Your Cuttings
For best results, use this simple method adapted from scientific protocols.
When to Collect Willow Shoots: For maximum efficacy, collect one-year-old shoots in January or February. A 2024 study on blackberries found that shoots collected during these months produced the highest rooting success rates, while those from August and October were significantly less effective (33.3%).
Simple Step-by-Step Recipe
Gather Materials: Collect fresh, one-year-old willow shoots (about the thickness of a pencil) and non-chlorinated water (I suggest clean rainwater).
Prepare the Branches: Strip the leaves and cut the shoots into 2.5-7.5 cm (1-3 inch) pieces. Lightly crush the pieces with a hammer to help release the active compounds.
Extract the Goodness (Cold Water Method): Place the chopped willow in a clean container (glass or ceramic is apparently best) and cover it with water. Let it soak at room temperature for 24 to 72 hours.
Strain and Store: Remove the willow pieces by straining the liquid. Store the finished willow water in a sealed jar in the refrigerator for 1-2 weeks.
🧪 How to Use It
Soak Cuttings: Place the bottom ends of your plant cuttings in willow water and let them soak for several hours or overnight before planting them in compost.
Water New Cuttings: After planting, water the cuttings with willow water. This provides an initial boost of hormones to the root zone.
When to Use Willow Water vs. Commercial Hormones
The research suggests a clear strategy for choosing the right product for the job.
Willow Water is Ideal for:
Gardening on a budget: It’s completely free to make at home.
Easily-rooted plants: Softwood and semi-hardwood cuttings of plants like roses, hydrangeas, buddleja, and many common garden shrubs.
Encouraging long, branching roots: As seen in the snowbush study, the roots it produces are often of higher quality with more secondary branching.
Commercial Rooting Hormones are Superior for:
Difficult-to-root species: For plants that are known to be a challenge, such as many fruit trees (apples, pears), lilacs, conifers, and cannabis, synthetic IBA products provide a much higher and more reliable success rate.
Commercial or large-scale propagation: When consistent, high-volume results are required.
The Bottom Line for UK Gardeners
Willow water is a fantastic, natural, and effective tool for many common garden plants, but it’s not a miracle cure.
Willow harvest in the food forest.
It works, and science confirms its active rooting compounds can be very effective, particularly when the willow shoots are harvested in winter.
It’s not a universal replacement for commercial rooting hormones, which are more reliable for difficult species.
You have nothing to lose by trying it on your own garden cuttings. It’s a rewarding, low-cost experiment that can be very satisfying when it succeeds.
I can find no research on the following, just anecdotal comment, but soaking the cuttings in willow extract and THEN using commercial products might work! BUT beware, this might supply too much hormone. So test application rates for yourself.
📚 References and Verifiable Sources
Mohammed, A. (2024). Rooting of thornless blackberry cuttings as induced by the extract of white willow (Salix alba L.) shoots collected in different times. arXiv. Available at: https://arxiv.org/abs/2405.08849 NB This is a pre-print so needs to be considered with caution.
Abd El-Rahman, S. (2024). Assessment the efficiency of willow water extract (WWE), indole-3-butyric acid (IBA) and micronutrients on the propagation of Petunia x hybrida by stem cuttings. Horticulture Research Journal. Available at: https://hrj.journals.ekb.eg/article_362981.html
El-Sayed, M., et al. (2023). The Natural Alternatives: The Impact of Plant Extracts on Snowbush (Breynia disticha Forst.) Cuttings’ Morpho-Physiological and Biochemical Characteristics. Horticulturae. Available at: https://doaj.org/article/2769c915cd404ecc9dc5c305b5a5307e
Cojocariu, A., et al. (2024). Use of biostimulating Salix solutions for the vegetative propagation of Chrysanthemum: a review. J. Plant Develop. Available at: https://plant-journal.uaic.ro/docs/2024/21.htm
Leclerc, C. & Chong, C. (1983). Influence of willow and poplar extracts on rooting cuttings. Proceedings of the International Plant Propagator’s Society. Available at: https://www.pubhort.org/ipps/33/120.htm
Stemeroff, J. (2018). Vegetative propagation of cannabis by stem cuttings: effects of leaf number, cutting position, rooting hormone, and leaf tip removal. Canadian Journal of Plant Science. DOI: 10.1139/cjps-2018-0038
Deniau, M., et al. (2019). Willow Extract (Salix cortex), a Basic Substance of Agronomical Interests. International Journal of Bio-resource and Stress Management. DOI: 10.23910/IJBSM/2019.10.4.2009
