01 - Rinse the dandelion flowers thoroughly under cool water. Remove all green parts from the flower heads, retaining only the bright yellow petals.
02 - Combine the petals and water in a saucepan. Bring to a boil, then reduce heat and simmer for 10 minutes. Remove from heat and let the mixture steep for 30 minutes.
03 - 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.
04 - Transfer the measured liquid to a clean pot. Stir in the lemon juice and fruit pectin until fully dissolved. Bring to a full rolling boil over high heat, stirring constantly.
05 - Add the sugar all at once. Return to a rolling boil and cook for 1 to 2 minutes, stirring continuously to prevent scorching.
06 - Remove from heat and skim off any surface foam. Immediately ladle the hot jelly into sterilized jars, leaving 1/4-inch headspace. Seal with lids.
07 - Process the sealed jars in a boiling water bath for 10 minutes for long-term storage, or allow to cool and refrigerate for immediate use.