Using a vegetable peeler, remove zest from two lemons, leaving white pith behind. Squeeze all of the lemons for 2/3 cup juice and set aside. In a large pot bring 5 1/2 cups of water and zest to a boil over high heat. Stir in the lavender. Partially cover the pot, lower the heat, and simmer for 10 minutes.
Meanwhile, place a large strainer lined with cheesecloth or a damp paper towel over another pot or heat-proof bowl. Strain tea, pressing on herbs to extract all liquid. Stir in honey until dissolved. Stir in lemon juice. Let cool completely, about 45 minutes. Fill four tall glasses with ice. Pour tea over ice and serve immediately.