In a large saucepan, add water and bring to a boil. Turn off. Add rosemary to hot/boiled water; cover and let stand for 15 minutes. Strain, reserving liquid.
If necessary, add water to measure 2.5 cups. Return liquid to pan; add pectin and vinegar. Bring to a full rolling boil over high heat, stirring constantly.
Add sugar and food coloring (optional); return to a boil, stirring until continually. Once temperature reaches 220 degrees F, stir for 2 minutes for a softer set. Boil for 4 minutes for a harder set jelly.
Recipe makes 3 half pints.
Notes
Jelly didn't set?
If your jelly didn't set, don't panic. Sometimes it can take up to 48 hours for the jelly to set. If, however, after that time it is still not set, follow the below instructions to reprocess:
Open each jar, empty jelly into large, clean stock pot.
Empty jars, lids must be re-washed and prepped again for canning.
To the stock pot, add 1/4 C. granulated sugar, 2 Tbsp lemon juice, 1/4 C. water and 3 tsp pectin.
Stir well and bring the mixture to a hard rolling boil (a boil that cannot be stirred down) for 1-2 minutes.
Ladle into jars, wipe the rims, and apply the lids and bands. Re-process in a water bath for 10 minutes.