How to Make “Willow Water” root hormone

Here is the procedure for making willow water:

1. 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 gray bark.
2. 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.
3. Take the twigs and cut them up into short pieces around 1" (2.5cm) long.
4. The next step is to add the water. there are several techniques to extract the natural plant rooting hormones:
   a) Place the chopped willow twigs in a container and cover with boiling water, just like making tea, and allow the “tea” to stand overnight.
   b) Place the chopped willow twigs in a container and cover with tap water (unheated), and let it soak for several days.
5. When finished, separate the liquid from the twigs by carefully pouring out the liquid, or pouring it through a strainer or sieve. The liquid is now ready to use for rooting cuttings. You can keep the liquid for up to two months if you put it in a jar with a tight fitting lid and keep the liquid in the refrigerator. Remember to label the jar so you remember what it is, and write down the date you brewed it up, and to aid the memory, write down the date that it should be used by, which is two months from the date it was made!  
6. To use, just pour some willow water 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. Then prepare them as you would when propagating any other cuttings.
   The second way to use willow water is to use it to water the propagating medium in which you have placed cuttings. Watering your cuttings twice with willow water should be enough to help them root.

Reprinted from https://deepgreenpermaculture.com/diy-instructions/home-made-plant-rooting-hormone-willow-water/