The last of the plums are well gone by now. We've even drunk most of the wine we made from them but it's been a great harvest / forage and I intend to double production next year. Plums are one of the least labor intensive crops to turn into wine. You can quickly pick enough for a batch and turning them into wine is easy.
Our approach was very unscientific and organic. After all, fermentation is a natural process.
My theory is that you are relying on the fruit itself and the ripeness of it, to give you a good result. For example the best batch I did this year was a carboy of Black Doris plums which were so ripe they were pretty much just juice inside the skin. We hardy had to add sugar or yeast, they just wanted to start fermenting. It was a sweet brew so we combined it with a dryer one we made earlier and it was a match made in heaven.
Can't wait for next season.
The brew below is the Black Doris, that's kombucha back left. Below that the dryer plums and below that the brew we made from them.