Willows are fast growing, deciduous trees that are mainly found in the Northern Hemisphere, in cold arctic and north temperate zones, in regions with moist soils. The Weeping Willow appears to be a native of extra-tropical Asia, from Japan and China to Armenia and the banks of the Euphrates, and of Egypt and North Africa.
One of the most popular and familiar willows is the Weeping willow (Salix babylonica), it has exceptional form and beauty. When mature it exhibits graceful, wide-spreading, pendulous weeping branches, with a short trunk, and a broad rounded crown. Its leaves are thin and narrow, sometimes with whitened or silky undersides. It is fast growing, and adaptable to almost any soil conditions.
Willows are an incredibly useful trees, with have many useful functions such as shade trees, for erosion control and timber production. Historically willow bark was used as a pain medicine as it contains compounds similar to aspirin!
Willows also have an uncanny growing ability! A broken willow branch left in water will very quickly grow roots. Willows can successfully root from very thick pieces of stem as thick as a human thigh when put into damp ground. This method of willow propagation is known as taking ‘trunk cuttings’. Willow cuttings can even grow if put in the ground upside-down, but please do the right thing and put them in the right way up!
These incredible growth properties of willows are due to the naturally occurring plant rooting hormones that they contain, which we can extract and use to induce rooting of cuttings of other plants we wish to propagate.
What Is Willow Water and How Does It Work?
Willow Water is a homemade plant rooting hormone that is easily prepared and can be used to increase the strike rate (growth of roots) of cuttings that we’re trying to propagate.
The way that it works can be attributed to two substances that can be found within the Salix (Willow) genus, namely, indolebutyric acid (IBA) and salicylic acid (SA).
Indolebutyric acid (IBA) is a plant hormone that stimulates root growth. It is present in high concentrations in the growing tips of willow branches. By using the actively growing parts of a willow branch, cutting them, and soaking them in water, we can get significant quantities of IBA to leach out into the water.
Salicylic acid (SA), which is a chemical similar to the headache medicine Aspirin, is a plant hormone which is involved in signalling a plant’s defences, it is involved in the process of systemic acquired resistance (SAR) – where an attack on one part of the plant induces a resistance response to pathogens (triggers the plant’s internal defences) in other parts of the plant. It can also trigger a defence response in nearby plants by converting the salicylic acid into a volatile chemical form.
When we make willow water, both salicylic acid and IBA leach into the water, and both have a beneficial effect when used for the propagation of cuttings.
One of the biggest threats to newly propagated cuttings is infection by bacteria and fungi. Salicylic acid helps plants to fight off infection and can thus give cuttings a better chance of survival. Plants, when attacked by infectious agents, often do not produce salicylic acid quickly enough to defend themselves, so providing the acid in water can be particularly beneficial.
How to Make Willow Water Rooting Hormone
Willow water can be made from cuttings of any tree or shrub of the willow family, a group of plants with the scientific name of Salix. The more cuttings that are used and the longer they are soaked in water, the stronger the resulting willow water will be.
Recommendations for the exact method of soaking vary. Cold water can be used, and soaking times of four or more weeks are often quoted. Other gardeners use a much faster and preferrable method using boiling water to steep the willow twigs and soak the mixture for around 24 hours.
Here is the procedure for making willow water:
- Collect young first-year twigs and stems of any of willow (Salix spp.) species, these have green or yellow bark. Don’t use the older growth that has brown or grey bark.
- Remove all the leaves, these are not used. Don’t waste good green material though, compost the leaves or throw them in the garden as mulch.
- Take the twigs and cut them up into short pieces around 2.5cm (1″) long.
- Place the chopped willow twigs into a jar, and if you’ve collected plenty of willow twigs, fill the jar almost to the top.
- To extract the natural plant rooting hormones, either fill the jar with boiling water to cover the twigs, just like making tea, and allow to stand overnight; or use unheated tap water and allow to soak for several days.
- Separate the liquid from the willow twigs by pouring through a strainer or sieve. The willow water is now ready to use for rooting cuttings.
The willow water can be kept for up to two months if it’s put into a jar with a tight-fitting lid and stored in the refrigerator.
Since willow water is a clear liquid, it’s a good idea to label the sealed jar as a reminder of what’s in it. Also include the date it was made and perhaps the use-by-date, which is two months after that.
How to Use Willow Water to Propagate Cuttings
To use willow water for propagating cuttings, pour some into a small jar, and place the cuttings in there like flowers in a vase, and leave them there to soak overnight for several hours so that they take up the plant rooting hormone. The cuttings can then be put into a propagating medium and prepared in the usual way to grow roots.
Here are two Julep mint cuttings rooting in water. Mint placed in water will strike roots on its own. What is interesting to not here is that the untreated control on the left is only rooting at the nodes, where the leaf buds were. That’s where most cuttings usually root. The cutting treated on the right was placed overnight in a jar of willow water first, and that has not only rooted at the nodes, but all along the stem that was sitting in the willow water!
The second way to use willow water is to use it to water the propagating medium into which the cuttings have been inserted. Watering the cuttings twice with willow water should be enough to help them root.
In summary, willow water is a natural plant rooting hormone that’s really easy to brew up, and costs nothing at all to make! So, next time you’re out on a hot summer’s day enjoying the shade and natural cooling provided by a majestic willow, grab a few twigs and take them home to help propagate some plants for your garden!
References
- University of Maryland Medical Centre, Medical Reference – Complementary Medicine – Willow Bark