Apples are genetic hybrids that produce new genetic combinations in their seedlings. To preserve the exact genetic variation, grafting is the usual method of propagation (and cutting is sometimes used). All the Granny Smith apple trees grown today are clones from the original Smith tree in Sydney.
Granny Smith apples are light green in colour. They are popularly used in many apple dishes, such as apple pie, apple cobbler, apple crumble, and apple cake. They are also commonly eaten raw as table apples, and at least one company (Woodchuck Hard Cider) makes Granny Smith varietal cider.
It is moderately susceptible to fire blight and is highly prone to scab, powdery mildew, and cedar apple rust.
Granny Smith is much more easily preserved in storage than other apples, a factor which has greatly contributed to its success in export markets. Its long storage life has been attributed to its fairly low levels of ethylene production, and in the right conditions Granny Smiths can be stored without loss of quality for as long as a year. This cultivar needs fewer winter chill hours and a longer season to mature the fruit, so it is favoured for the milder areas of the apple growing regions. However, they are susceptible to superficial scald and bitter pit. Superficial scald may be controlled by treatment with diphenylamine before storage. It can also be controlled with low-oxygen storage. Pit can be controlled with calcium sprays during the growing season and with postharvest calcium dips.
Granny Smith are distinctive in being bright green when ripe. Granny Smith is one of several apple cultivars that are high in antioxidant activity, and they have the highest concentration of phenols amongst the apple breeds. Some sources recommend Granny Smiths (among other apples) as a particularly efficient source of antioxidants, particularly the flavonoids cyanidin and epicatechin, especially if eaten with the skin intact. Granny Smiths are also naturally low in calories and high in dietary fiber and potassium, making them commonly recommended as a component of healthy and weight-loss diets.
According to the US Apple Association website, it is one of the fifteen most popular apple cultivars in the United States.