Calgary Mac Apple TreeCalgary Mac is a prairie bred McIntosh type from Calgary Alberta. Medium fruit with red over green skin and crisp juicy flesh with classic sweet tart Mac flavor. Ripens early to mid October and keeps a few weeks in cold storage. Susceptible to scab in wet seasons; monitor and prune for airflow. Cold hardiness: Zone 3bPlant Details One year old trees grafted onto one or two year old rootstocks. Apple trees are typically 12 to 20" tall.