Clip and discard bitter white bases from the rose petals; rinse petals thoroughly and drain.
Place rose petals in a bowl and sprinkle enough sugar to coat each petal. Let set overnight.
In a saucepan over low heat, place remaining sugar, water, and lemon juice; stirring to dissolve sugar. Stir in rose petals and let simmer 20 minutes. Increase heat to medium-high and bring to a boil; continue boiling for approximately 5 minutes until mixture thickens and the temperature on a candy thermometer reaches 221 degrees F. or until a spoonful dropped onto a cold plate jells and holds its shape. Remove from heat.
After boiling, transfer the jam into hot sterilized jars. Fill them to within 1/4-inch of the top. Wipe any spilled jam off the top, seat the lid, and tighten the ring around them. Cover, label, and store in a cool place.
* All roses that you intend to eat must be free of pesticides. Do not eat flowers from florists, nurseries, or garden centers. In many cases these flowers have been treated with pesticides not labeled for food crops. The tastiest roses are usually the most fragrant roses. Learn more about Edible Flowers.
Rose Petal Jam Recipe: https://whatscookingamerica.net/EllenEaston/RosePetalJam.htm