Pick fresh dandelions from an untreated area. Remove the yellow petals from the green bases, keeping only the soft petals to avoid bitterness.
Place the petals in a saucepan and pour in the water. Bring to a gentle simmer, then remove from heat and cover. Let the mixture steep for 30 minutes to extract the floral flavor.
Pour the steeped mixture through a fine mesh strainer or cheesecloth into a bowl, pressing lightly on the petals to release all the liquid. You should have about 3 cups of golden dandelion tea.
Pour the strained tea into a large pot. Stir in the lemon juice, lemon zest, and powdered pectin. Bring the mixture to a rolling boil over medium-high heat, stirring constantly.
Add the sugar all at once and continue stirring. Bring the mixture back to a full boil that cannot be stirred down. Boil for 1 minute.
Remove from heat and stir in the vanilla extract if using. Skim off any foam from the surface.
Carefully ladle the hot jelly into sterilized jars, leaving about ΒΌ inch headspace.
Wipe jar rims clean, add lids, and process in a boiling water bath for 10 minutes to seal.
Allow jars to cool completely at room temperature. The jelly will set as it cools, forming a clear golden spread with a light floral flavor.
