Add lavender and heat, stirring occasionally, until the syrup comes to a simmer. Once simmering, remove syrup from heat, cover, and set aside to infuse for 15 minutes or until it reaches your desired potency.
Uncover and whisk in optional pea powder to adjust the color. Add a squeeze or 2 of lemon juice, if desired, for a lighter purple shade and brightened flavor.
Strain the syrup and transfer to a lidded jar or bottle. (Discard the lavender flowers.)
Use the syrup as desired or store in the refrigerator for up to 1 month.