The very first blueberries I found on the 30th of May at the Lippischer Velmerstot's peak, the last time I collected blueberries this year was on August the 1st on a lower hillside. There were still plenty of berries, but collecting them was much harder already compared to end of June/early July. Hence I didn't collect more blueberries later again. While I combined the first blueberries with some raspberries, the last harvest I combined with blackberries. Those blackberries were the first of this year and I collected them until September the 15th. There are still many blackberries to find, but the later the year, the more difficult it is to get a good quality of blackberries.
I traded a few glasses of my jam for some self made strawberry jam that was pretty delicious, too. But all in all I like blueberry and blackberry jam more. And these jams are even more healthy, too. Blackberries and Blueberries both contain Vitamin C, some Flavonoids and minerals, blueberries are famous for their health supporting abilities since ages, Hildegard von Bingen praised them particularly
I am still considering to collect a few fruits of the mountain ash and try to make jam of that, too. Never tried that before, but it is said to be delicious, too