Remove the lavender flowers from the stems (there is no need to strip them) and lay them in a medium basin to prepare them (preferably not Pyrex, which can crack when you add boiling water).

Using your (clean) fingers, gently rub the petals into the sugar after pouring it over them.

Pour 2 cups of boiling water over the lavender sugar and stir with a spoon until the sugar has melted to make the lavender simple syrup. For 30 minutes, cover and allow to infuse.

Pour the strained simple syrup—which has been infused with lavender—into a serving pitcher or carafe.

Add the lemon juice and stir. Add two more cups of the iced water. Adjust for tartness after tasting. If it's overly sweet, add additional lemon juice. If it's too tart, add extra sugar. To reach the appropriate level of concentration, add more water and ice.

Keep in mind that when the ice melts, the beverage will become even more diluted.

If you'd like, garnish the serving pitcher with a few lavender sprigs and some thinly sliced lemons.