First, harvesting the dandelion greens. Begin by just taking the heads of the dandelions. Plan on trimming them soon after you take the heads from the plant. I find it easiest to hold the flower end in one hand and cut the green end off. Then peel the remaining green off. Measure 4 cups worth of blossoms.
Bring a few quarts of water to boil and pour it over the blossoms in a bowl that can be covered. Allow this to come to room temperature and then stick it in the fridge overnight.
The following day, start heating your water bath canner with enough water to cover your jelly jars with at least 2 inches of water.
Measure 3 cups of the dandelion tea, straining out the blossoms and keeping only the liquid. Pour this into a larger kettle. Add powdered pectin and the 2 T of lemon juice. Bring to a boil.
Once you have achieved a rolling boil, add sugar. Return to a rolling boil, stirring quite often, if not always. Once you have reached a rolling boil, time for 1 minute, stirring the whole time.
Ladle jelly into prepared jelly jars, wiping the edges, adding lids, and putting rings on to finger tip tight. Put into water bath canner and process for 10-15 minutes. I did 15 minutes because my altitude is greater than 1000 feet. Remove from canner and allow to cool for 12-24 hours before moving.