Taming raspberry bushes - Blog poster says, "When setting out the new plants they were spaced about 18" apart - but over the years they will spread and quickly fill in the entire bed with new shoots every year. It is important to prune out the old canes every winter when they are dormant."
Also on these boards
We're going to do something very similar to this in between our raised beds to grow pea plants on this summer. It will be like a living tunnel for the kids to play in.