According to Payments Canada, which regulates the process of clearing and settling financial transactions in Canada, regular cheques and provincial government cheques are stale-dated after 6 months and can't be deposited. Your bank can decide – at its own discretion – whether it will honour stale-dated cheques, though it's under no obligation to do so.
In contrast, Payments Canada rules state that money orders, bank drafts and federal government cheques never stale-date.