Step 1: Rinse the dandelion petals thoroughly to remove any dirt or insects.

Step 2: In a large pot, combine the dandelion petals and water. Bring to a boil, then reduce heat and simmer for 10 minutes.

Step 3: Strain the liquid through a fine mesh sieve or cheesecloth into a bowl, discarding the petals. You should have about 3 cups of dandelion tea.

Step 4: Return the dandelion tea to the pot and add lemon juice, powdered pectin, and a pinch of salt. Stir well.

Step 5: Bring the mixture to a rapid boil over high heat, stirring constantly.

Step 6: Add the sugar all at once and return to a full rolling boil. Boil hard for 1 minute, stirring continuously.

Step 7: Remove from heat and stir in vanilla extract and butter to reduce foaming.

Step 8: Skim off any foam and quickly ladle the hot jelly into sterilized jars, leaving 1/4-inch headspace. Seal immediately.

Step 9: Let the jars cool to room temperature before storing in the refrigerator.