Combine dandelion petals and 4 cups boiling water in a glass jar. Allow to steep until cool or overnight
Strain mixture through a fine mesh strainer, and measure 3 cups of the liquid into a stainless pot
Add 2 tablespoons lemon juice and 1 package of powdered pectin. Combine and bring to a full boil
Add 5 1/2 cups sugar all at once to the mixture and stir continuously. Bring mixture to a rolling boil and cook for 2 1/2 minutes
Ladle jelly into clean jars leaving 1 inch headspace
Wipe rims of jars with clean cloth dipped in white vinegar to remove any residue
Place lid on top and add ring to finger tightness
Place jars into waterbath canner. Bring to a boil and process for 10 minutes
Remove lid and allow jars to sit 5 minutes before removing from canner
Allow jars to cool 24 hours. Remove rings and label
Jars are shelf stable for one year or longer