Note: Never harvest dandelions from areas that have been treated with pesticides or other chemicals, such as what you might find in a typical lawn. See more information on harvesting and cleaning dandelions.
Rinse them quickly in cold water and snip off the stems and green collars under the blossoms. Boil the petals in 2 quarts of water for 3 minutes. Cool and strain, pressing the petals with your fingers to extract all the juice. Measure out 3 cups of the dandelion liquid and place in a large jelly kettle. Add 2 tablespoons of lemon juice and 1 package of powdered fruit pectin (1 ¾ ounces). Bring the mixture to a boil. Add 5 ½ cups of sugar, stirring to mix well. Continue stirring, and boil the mixture for 2-½ minutes. Pour into small glasses and cover with paraffin when the jelly is cool.