clean and sterilize 4-5 half pint jars, fill with boiling water to keep warm

get a boilng water bath going to seal the jars in

place the diced plums in a deep pot, this jam will bubble up while cooking, a deep pot makes it easy to keep it under control

add the sugar and stir to combine

turn the heat to medium low

when the plums start to juice raise the temperature to medium and keep cooking

stirring in the lemon zest, lemon juice and rose petals at this time too

keep cooking and stirring, you don't want the jam to scorch but you need to get the temperature to 220˚ for a gel

once it really starts boiling away it will boil up and then the volume will reduce

you can begin checking for set soon after this point

take a chilled plate from the freezer and plop a bit of jam on it, let it rest there and cool, if it gets firm and sets up a skin it's ready, if not keep cooking and try again in a few minutes

OR if you have a candy thermometer clip it on and cook until it reaches 220˚

once it reaches 220˚ it's ready to go in the jars

skim off any foam, set this aside as a kid treat, eating this is the BEST part of mom making jam

dump the warm water out of the jars, pour in the hot jam, wipe the rims, cap them and seal them in a boiling water bath 1 inch deeper than the lids of the jars for 10 minutes