I am sorry for this delayed reply to your gardening question. The spring rush has brought a deluge of questions and we are working hard to catch up!
Blackberries can be planted anytime but the plants are usually available in the late winter season. You can grow them in a very large planter but there won't be many plants and yields will be rather low.
Thanks for the question. Best wishes for a wonderful gardening season. Please stop in again soon!
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