I grew 3 varieties of raspberries in 20 gallon grow bags last year because I knew we would be moving last fall and wanted to take them with me. I should have known better but left them in the yard of the new house where I hadn't planned on planting them. Well they grew right through the bottom of the grow bags and into the soil and when I moved them this spring I could feel/hear the roots tearing between the bags and the ground. It took all of about 3 weeks for half a dozen new raspberry plants to shoot up where the grow bags had been previously sitting. Easy enough way to propagate brambles I guess.