Wash lemon balm well, drain and place in heat-proof glass or nonreactive bowl.
Pour boiling water over petals and let steep from 30 minutes to 24 hours.
It usually takes about two hours for violets.
Strain through a fine sieve, reserving the liquid or infusion.
If not using immediately, refrigerate up to 24 hours.
To make the jelly, stir lemon juice and sugar into reserved infusion in a two-quart nonreactive or stainless steel pan.
Bring to a full rolling boil that cannot be stirred down.
Add the liquid pectin and continue to boil two minutes, skimming any foam that may rise to the surface.
Ladle quickly into jars to within about 1/8 inch from the top; clean each rim and threads of the jar as it's filled, and place flat lid and ring on each before filling the next.Place the jars in a hot-water canning bath and boil for 10 minutes (or the appropriate time for your area).