01 - Rinse the dandelion flowers thoroughly under cool running water. Pinch off and discard all green base parts, retaining only the bright yellow petals.
02 - Combine the prepared petals and water in a saucepan. Bring to a boil, then reduce heat and simmer gently for 10 minutes.
03 - Remove the saucepan from heat and let the mixture steep uncovered for 30 minutes to develop full flavor.
04 - Pour the mixture through a fine mesh sieve or cheesecloth, pressing firmly to extract all liquid. Discard the spent petals. Measure the reserved liquid; it should yield approximately 3 cups.
05 - Transfer the measured liquid to a clean pot. Stir in the lemon juice and fruit pectin until fully dissolved.
06 - Bring the mixture to a full rolling boil over high heat, stirring constantly to prevent scorching.
07 - Add all of the sugar at once. Return to a rolling boil and cook for 1 to 2 minutes, stirring continuously. Remove from heat and skim off any surface foam.
08 - Immediately ladle the hot jelly into sterilized jars, leaving 1/4-inch headspace. Wipe the rims clean and seal with lids.
09 - Process the sealed jars in a boiling water bath for 10 minutes for shelf-stable storage. Alternatively, let the jars cool to room temperature and refrigerate for immediate use.