storeing plums for jaming

I'm the lazy type and I simply washed, halved, and stoned the fruit before putting into freezer bags. Once it's cooked later, it doesn't make any difference. All depends whether or not you want the skins in the mix or if you'll be sieving them out after cooking and before jamming. If you like skins in your jam, then coarsely chop them before bagging and freezing.

If the plums are ripe, the stones come out quite easily. You don't even need a knife; fingers will work just fine.

I leave the skins on while cooking as it seems to help the pectin/setting part, but I squish everything through a sieve for jams and that catches all the skins. I'm not sure I could do a plum jelly.