In a heat-safe bowl, combine the hibiscus, boiling water, and 1 cup sugar. Stir until the sugar dissolves, then allow to steep for 5-10 minutes, while you prepare the rest of the lemonade.
Squeeze the lemons. If you don't have enough fresh lemons, you can top up with bottled lemon juice.
In a large pitcher, combine ¾ cup of the sweetened hibiscus tea (set some aside for now), lemon juice, and 3 cups cold water and stir. Give it a taste and see if it needs more sugar (then add the rest of the sweetened hibiscus), or if it needs more water. Once you're happy with the flavor, enjoy immediately over ice, or chill before serving.
The number of lemons you will need will vary depending on how much juice your lemons have. I typically use 6-8 lemons. Get a few extras just in case, or you can always top up with bottled lemon juice if you don't have 1 cup of fresh lemon juice. You just want more freshly squeezed lemon juice than bottled lemon juice for the freshest flavor.