Combine the honey, lavender buds and 3 cups water in a saucepan over medium heat. Bring just to a boil, stirring to dissolve the honey. Set aside and allow to cool completely, then cover and refrigerate overnight.
Add the lavender sprigs and the lemon juice to a large measuring cup and muddle to release the lavender oils. Strain the honey-lavender water and combine it with the muddled lemon juice. Let sit for 15 minutes before removing the lavender sprigs. Divide the lemonade between two 2-cup to-go containers. Refrigerate until ready to serve.
Divide the vodka, if using, between the containers. Add some frozen grapes to keep the drink cold! Serve.