For the second year in a row, our raspberries don't start producing until the first week in October. I got the plants from a friend who gets raspberries in July and August. I wonder if I don't prune any of the growth whether that may solve the problem. In the past I did as they suggest-- prune the old plants, but that hasn't made any difference. Currently the plants have lots of immature berries but they'll never make it due to frost. Any ideas or suggestions?
Raspberries Don’t Produce Until October
Possibly the plants are really too old. Some experts recommend that raspberries be totally discarded after 12-15 years, and new ones purchased from a nursery.
Possibly you cut the wrong canes. You could try leaving them all till next season, and see what happens.
Or the problem could be cultural, especially too much nitrogen or too much shade.
Here's an article I found, rather long, but it appears to have all the information you'll ever need about raspberries: http://polk.uwex.edu/files/2014/02/Growing-Raspberry-in-WI-A1610.pdf