In a 4 cup measuring cup, add 1 cup dried hibiscus, 1 tbsp dried lavender, 3 cups water. Microwave 4 minutes, let steep for 20 minutes.
While tea is steeping, juice the lemons and pour into a one gallon pitcher.
Once tea is done steeping, strain into a large bowl with a pour spout.
Add 1 cup sugar and Jamaica tea mixture to the pitcher. Fill with water to the 3-liter line. Stir to incorporate the sugar. Refrigerate until cold.