I just planted two unnamed blackberry cultivars in a raised bed with rhubarb surrounded by flagstone. It seemed like a good idea at the time but now based on a remark about how they are a "nightmare to control" I'm having second thoughts.
Do they send out a lot suckers?
Can they be controlled by yearly hard pruning?
How far will the suckers extend? More than a few feet?
Edit: I cannot mow the plants down in a raised bed. Is it feasible to plant them in a bottomless pail so they only send new canes from the base of the roots and not send suckers under my flagstone path?
Edit: in 2015 the blackberries have been planted for three years in a shady area with good soil and water and three competitive rhubarb plants. Last winter in USDA zone 4 they were killed to the ground but still managed to grow ten feet in a season. No berries though. Rhubarb is doing great!