Description

General aspect and origins - Citrus aurantium is also known as the bitter orange, or Seville orange, that belongs to the Citrus genus. This is a small evergreen tree that can reach 15 to 25 ft (about 5 to 7 m) tall, and which is native to China. It has spread to many subtropical and Mediterranean areas, and especially areas where winters are slightly too cold for other Citrus.
Leaves - Bitter orange has deep green evergreen leaves. It generally has winged leaves, but some selections and varieties do not have that feature.
Flowers - Bitter orange is famous for its sweetly fragrant white flowers.
Fruits - Bitter orange or Seville oranges are rounded, sometimes slightly flattened fruits, with a rough orange skin. These fruits are generally not eaten fresh, but are rather transformed into marmelades, drinks, or are candied.

Culture

The bitter orange may withstand brief negative temperatures down to -10°C. This tree can thus be grown in USDA zones 9a and warmer, and may be tried in most sheltered areas in USDA zone 8b.
Soil - This Citrus requires a slighly acidic and well-drained ground.

Propagation

Unlike most other Citrus, Citrus aurantium is often propagated by seeds. However, grafting or air layering gives quicker results.
A bitter orange contains up to 20 seeds. To propagate this Citrus by seeds, fresh seeds should be used.

Pests and diseases

The bitter orange, like many other Citrus, is susceptible to various diseases like tristeza or exocortis, and various pests like the Mediterranean fruit flies.