I know you can plant raspberries anytime around here. You just need to keep them watered until fall. Make sure when you take canes from others gardens that the variety is one that you will really like to grow. When I moved into my place it was just a grown over mess with some straggly raspberry canes here and there. Having 2 huge lots without plants to fill it up with I dug the stray canes up and started a raspberry patch. Well that was 6 years ago and I know have a row of canes 20 feet long. I get tons of berries but I do believe they came from a variety that were bred to store or ship better than many of the better tasting canes available now.I can pick a bowl of these things and 2 days later they are still in good shape just sitting on the counter. They don't taste bad but they certainly don't have the flavor of some i have tasted. If I was ever to move and start over I wouldn't replant these canes. I have given 100's of canes away to people and none of them have complained but the way I see it is "why not start with the very best" You don't need to buy too many canes to end up with more than you need in a year or two so the cost isn't a big factor.
Raintree Nursery in Morton, Washington is a good place to buy fruit trees and other goodies that do well in Western Washington.They have good information on growing too.
I am not sure that the Spelling is correct (Raintree) but I bet if you look it up you can find it on the web.

if you live in southern calif where the temp are in the high 70s wait until sept-mar to plant your blackberries...in the meantime compost and prepare the soil for the dec-jan planting....hope this helps...jim