Harvest and prepare about 8 cups of dandelion flower heads, removing the yellow petals and discarding the green parts.

Place the dandelion petals in a large heatproof container and pour 4 cups of boiling water over them. Steep for at least 1 hour, ideally up to 24 hours.

Carefully strain the mixture using a fine mesh sieve or cheesecloth, yielding 3¾ to 4 cups of dandelion tea.

In a heavy-bottomed saucepan, combine the dandelion tea, 1/4 cup of lemon juice, and powdered pectin. Bring to a vigorous boil.

Gradually stir in 5 cups of sugar while maintaining a hard boil for 1-2 minutes, stirring constantly.

Ladle the hot jelly into prepared sterilized jars, wipe the rims, and screw on the lids. Let cool at room temperature for 12-48 hours.