I’ve never made it, but a quick google search brought up this from recipegal.com:
Rose Petal Jam
1 cup fresh rose petals (must never have been sprayed with any chemicals)
1 1/2 cups water, divided
Juice of 1 lemon
2 1/2 cups sugar,
1 package pectin (ie. Sure Jell)
3/4 cup water
Puree rose petals, 3/4 cup water, and lemon juice in blender until smooth; slowly add sugar. Blend untill all the sugar has dissolved; (leave in blender). Stir 1 package pectin (ie. Sure Jell) into remaining 3/4 cup water, bring to a boil; boil hard for 1 minute. Pour mixture into blender with rose petal mixture until well blended. Do this very quickly - it sets up FAST!! Pour into baby food jars. Let set for 6 hours, till firm. Will keep one month in refrigerator. Freezes well.