Prepare the lavender syrup by combining 1 cup of sugar and 2 cups of water in a medium saucepan over medium heat. Stir until the sugar completely dissolves, about 2-3 minutes.
Add the dried lavender buds to the sugar solution, stir briefly, then reduce heat to low. Allow the lavender to infuse for 10 minutes, occasionally pressing the buds against the side of the pan to release more flavor.
Remove from heat and let the syrup cool completely, which allows the lavender flavor to fully develop (about 30 minutes). The longer you let it steep, the stronger the lavender flavor will be.
Strain the lavender syrup through a fine-mesh sieve into a large pitcher, pressing on the lavender buds to extract all the flavor. Discard the used lavender buds.
Add the freshly squeezed lemon juice to the pitcher and stir to combine with the lavender syrup. Fresh juice makes a significant difference compared to bottled alternatives.
Pour in the remaining 3 cups of cold water and honey (if using), then stir until thoroughly combined. Taste and adjust sweetness if needed.
Refrigerate until well-chilled, at least 1 hour for the flavors to meld beautifully. The lemonade will keep for up to 3 days refrigerated.
Serve over ice in glasses garnished with fresh lavender sprigs and lemon slices for an elegant presentation that hints at the flavors within.