Citrus - Orange Washington Navel Citrus sinensis

The sweet orange's culture comes from the NC State toolbox, an American reference. It asks for direct sun and suggests a place with early morning sun in the growing season, so that new growth does not freeze: it calls the tree frost tender. The soil is a well-drained loam or sand, kept moist, at a pH of 5 to 6 for preference, with neutral or alkaline soil tolerated; the tree is drought tolerant, it says, but flourishes when kept moist and should not be overwatered. Its attributes table also ticks resistance to heavy shade and wet soil, where its text asks for direct sun and no overwatering; this page follows the text. Fruit comes on new wood, so pruning waits until the fruit has ripened. Its American list of problems: citrus rust mite, scales, mealybugs, whiteflies, aphids and fruit flies; greasy spot, stem-end rot, sweet orange scab, citrus canker and citrus greening.

The Riverside collection, a Californian reference, adds what is the navel's own: its notes call navel orange trees, and Washington in particular, not very vigorous. The description it quotes says the variety is sensitive to heat and aridity during bloom and fruit set, which restricts the climates it suits, and that in Florida it produces poorly, with coarse fruit of poor quality, and calls it clearly ill adapted to hot, semitropical climates. No Australian reference was read for its climate or frost: this page has no climate zones and no frost figure. The status of exotic rests on the quoted description's line that the variety was introduced into Australia in 1824; the Atlas holds a name entry for Citrus sinensis with no state records or status text.

The NC State toolbox lists the sweet orange for a container, a lawn or as a houseplant, for an edible garden, and as a flowering or small tree, and gives its bloom as winter and spring. The HortOS community garden cost guide lists the Washington Navel in its table of plants. The description the Riverside collection quotes says the fruit stores and ships relatively well but processes poorly, and in 1967 ranked Washington a major variety second only to Valencia.

The table above shows the sizes growers list; the community garden cost guide gives a 400 mm pot as the size the most growers price for this orange. No saved text says how the Australian trade propagates it or what size it reaches here, so ask the grower. For roots and pests see the HortOS guide to judging nursery plant quality. Stock that crosses a state border moves under the state and territory biosecurity rules; the HortOS guide to buying from a wholesale grower says nursery stock moving interstate may need a plant health certificate.

The NC State toolbox says the sweet orange can cause contact dermatitis in some people and records thorns on the species; no reference read says whether the Washington Navel itself has thorns. The toolbox, a plant finder and not a poisons register, also lists the species as poisonous to humans at low severity and a problem for cats, dogs and horses.