Posted: 30/01/2014 at 19:00
They do prefer a slightly acid soil Cherry3, so you do need to get that test done.
Have you been feeding them with anything? Raspberries are quite hungry plants and need something high in phosphates to fruit well. I would recommend mulching them with 2-3 inches of well rotted farmyard manure in early spring but if that's not available, use fish, blood and bone and a layer of multi-purpose compost as a mulch.
If your soil turns out to be alkaline, you could also try feeding them with an ericaceous feed such as one meant for rhododendrons and azaleas which would also be a good feed for your blueberries. You'll need to keep using this permanently though as chalky soils will always revert to becoming alkaline over time, even if you dig a big hole and fill it with ericaceous compost!