It might be worth adding to Wu Wei Wu's comment on the 15kg personal amount, that this is a federal (Canada) requirement. Individual provinces may also have tax laws that need to be checked. For example, Ontario (my province) is moving toward a certification process that may apply to growing for personal use. The exemption period ends Dec. 31, 2014, after which it appears any grower will need to apply for certification (_http://www.fin.gov.on.ca/en/tax/tt/rawleaf.html). Other provinces may also be moving toward further regulating tobacco growing, so check your provincial laws as well.
Regarding cooperative growing. I like the idea of pooling resources for such an important product. But such a venture would not be without its risks. Since tobacco is regulated in many countries, one would need a really good lawyer to help determine the risks associated with such a venture, including legal liability should a member turn against the group and try to sue for "harm". As well, we may see the day when the war on drugs extends to tobacco, which, considering the success at vilifying tobacco, probably could be initiated with little public resistance. Some things might be better done in a legally-compliant manner without drawing attention.
Gonzo