Yes, I think it would be a challenge for me to round up enough berries for jelly. I usually only see a few berries here and there. There are plenty of roots to harvest though. I read that if you push the unused part of the plant back into the soil after cutting off the roots it will typically regrow.Wow. I knew nothing about this use, either. I use their blooming to guide my first sowing of pea seed .
The old fellow who was the property owner and garden neighbor a number of years ago was from an orchardist family. A large Oregon Grape(s?) separated our gardens. He made jelly every year.
My current neighbor set out nearly a dozen bushes about 3 years ago. I have thought about offering to harvest the berries for jelly use but they still don't seem very productive.
Steve