Sweet Orange

Sweet orange is a frost-tender, perennial evergreen tree that needs full sun and, in the growing season, benefits from a site with early morning light so tender new growth isn't caught by overnight cold. It tolerates a soil pH from about 5 to neutral or slightly alkaline, is drought tolerant once established, and flourishes when kept consistently moist without being overwatered. Because it dislikes root disturbance, young transplanted trees should be set in their permanent outdoor position while small, or, in colder zones, grown in a container that can be moved indoors for winter and shifted carefully into larger pots as needed. Seed germinates in about two to three weeks around 54°F, and the tree should not be exposed to temperatures below about 55°F.

Pruning: Because flowers and fruit form on new wood, pruning should be delayed until after the current crop has ripened so that next season's fruiting wood isn't removed.

Sweet orange scab, caused by the fungus Elsinöe australis, produces corky, raised pustules on fruit and water-soaked leaf spots that can stunt young nursery trees or new field plantings and cause premature fruit drop. The damage is superficial and does not affect fruit quality, but the blemishes reduce marketability, and the fungus spreads through rain, irrigation, and the movement of infected plants; there is no cure, so prevention relies on not transporting citrus trees and inspecting trees regularly for symptoms.

Pests and other diseases: The tree can also be affected by citrus rust mite, citrus snow scale, purple scale, Florida red scale, mealybugs, whiteflies, aphids, and fruit flies, as well as diseases including greasy spot, stem-end rot, citrus canker, and citrus greening disease.

Fruit displays and ripens in winter and spring, developing a rind and pulp that turn orange as the round to slightly oval fruit, typically two to five inches across, reaches sweetness.

Culinary: The juice is used fresh and processed into jellies, ice cream, sherbet, and sorbet, while the rind flavors cakes and icing or is made into marmalade; the flowers can be cooked as a vegetable or steeped for tea.

Ornamental: The tree is grown for its glossy evergreen foliage and clusters of fragrant white flowers, which are showy enough that the blossom serves as the state flower of Florida, and it is also kept as a houseplant or container specimen.

Industrial and cosmetic: Oil pressed from the seed is used in soap making, the fruit's fragrance is captured for perfumes and cleaning products, and bergapten from the fruit is used in tanning lotions to promote skin pigmentation.

Sweet orange is a hybrid resulting from a cross between a mandarin orange and a pomelo, though when this cross occurred is not fully known; its common name reflects an origin traced to China. The species is native to Southeast Asia and East Asia, and from there it spread through cultivation and trade to become established across tropical and subtropical regions worldwide.