The Granny Smith apple tree is a popular, high-yielding, and vigorous deciduous tree known for producing firm, bright green, tart-sweet apples perfect for baking and fresh eating. Thriving in USDA zones 5-9, it requires full sun, 400-600 chill hours, and cross-pollination from another variety like Gala or Fuji. Trees grow 12-20 feet tall, with fruit ripening from late September to October. 
Key Characteristics & Overview
Fruit Profile: The fruit is iconic for its bright green, glossy skin (sometimes turning yellow when overripe) and crisp, firm white flesh. It is heavily used in pies, salads, and caramel apples because it retains its shape when cooked.
Tree Size: Depending on the rootstock, trees can be standard (15-20 ft), semi-dwarf (12-16 ft), or dwarf (8-12 ft).
Pollination: Granny Smith is not self-fertile and requires a pollinator (another apple tree) in the same or adjacent bloom group (Pollination Group B).
Harvest & Storage: Fruit ripens late in the season (late September through October) and is an excellent keeper, lasting up to 6 months in cold storage.
Growing Requirements:
Zones: 5-9.
Light: Full sun (6-8+ hours daily).
Soil: Prefers well-drained, slightly acidic to neutral, fertile soil.
Chill Hours: Approximately 400-600 hours.
Maintenance: Requires annual pruning in late winter to maintain shape and encourage airflow. They are moderately resistant to apple scab but susceptible to aphids and codling moths. 
Originating in Australia in 1868 from a chance seedling found by Maria Ann "Granny" Smith, this variety has become one of the most popular and versatile apple trees for home orchards.