Pour your witch hazel into a small saucepan. Turn the heat to low, and heat until medium warm, but not boiling.
While heating the witch hazel, crush the lavender and the juniper berries. Add the herbs to the witch hazel, turn down the heat, and let the mixture steep for five to seven minutes.
Then, remove the mixture from the heat and let it come to room temperature. Strain the mixture with the mesh strainer, and then store it in a colored, airtight bottle, being sure to label the mixture with the ingredients and the date.