In a 6- or 8-quart saucepan, bring water to a boil. Add flowers, stir and simmer over medium heat for 10 to 12 minutes. Turn off the heat and let the mixture cool a bit.
Strain mixture into a large container (with a lid to cover later), and add the sugar and lime juice. Stir until well-dissolved.
Once the concentrate has cooled, cover well and refrigerate. It will keep in the refrigerator for months.