Simmer the petals in the water for 10 minutes, then cover and let steep for about an hour.
Strain the petals through a fine mesh sieve, pressing out all the liquid.
Place a small plate in the freezer (to test jelly).
Return the liquid to the pot (rinse it clean!) and add the sugar, lemon juice and pectin.
Bring to a rolling boil and cook at least 1 minutes to allow the pectin to activate.
Test jelly on frozen plate to check for desired "gel" consistency. Spoon a small amount on plate, it should hold when plate is tilted.
Pour into sterile jars, place lids and rings on jars, and process in a water-bath canner for 10 minutes. You could also cool and store in the refrigerator.
Makes about three, ½ pint jars.
Recipe by The Patchy Lawn at http://thepatchylawn.com/recipes/from-the-garden/dandelion-jelly/