Bring water to a simmer in a medium pot. Do not boil vigorously as it can make the green tea bitter. Look for small bubbles forming along the sides of the pot.
Remove the pot from heat and add the hibiscus flowers and rose petals. Allow these florals to steep for 8 minutes, letting the water turn a deep ruby red color.
Add the green tea bags to the hot mixture and steep for an additional 3-4 minutes only. Oversteeping will cause bitterness, so set a timer for this step.
Strain the tea through a fine-mesh strainer into a heat-resistant pitcher, pressing gently on the solids to extract all the liquid.
Stir in your chosen sweetener while the tea is still warm to ensure it dissolves completely. Start with less – you can always add more after tasting.
Add the cold water to the pitcher and stir well to combine. This quick-cooling method helps preserve the bright flavor.
Refrigerate for at least 2 hours until thoroughly chilled. The flavors will continue to develop and meld during this time.
Serve over ice with lemon slices and mint leaves if desired. For a special touch, freeze edible rose petals in your ice cubes.