Begin by cutting a willow branch from a willow tree. It is important you do not use "dead fall", that is, a branch that fell from the tree on its own. The branch needs to be alive when you cut it from the willow tree. The length of the branch depends on the thickness of the branch and how much tea you wish to make. A branch about 1/2 inch thick at its thickest point and about 6 feet long will make about one cup of willow branch when cut up. You may consider using up to 3 different branches, again, depending on the amount of tea you would like to use.
Use a scissors, small saw, or knife to cut the branch into pieces between 3 and 4 inches long. This will help to release the rooting hormone from the bark. Put the pieces into a measuring cup in order to ensure proper proportion between the willow branches and the water for the tea.
Put the willow branch pieces into a large pot and pour in enough water to ensure proper proportion: one cup willow branch pieces to one quart of water. Be sure to cover the pot with the lid. Cook the tea at medium-high heat for 20 minutes.
After cooking the tea for 20 minutes, turn off the heat but do not move the pot. Let the pot sit, undisturbed, for 8 hours or overnight.
Take the willow bark tea out of the pot and put it in glass or plastic storage containers, or put it directly into a spray bottle. Store the rooting hormone in the refrigerator up to two months.
When using the willow bark tea for rooting plants, be sure to dilute it with equal parts water. Use in place of watering occasionally until plants are established. Either water the plants gently with it or use it in a spray bottle.