How to grow Orange

Citrus × sinensis · sweet orange, orange tree

The sweet orange is an evergreen citrus tree, on average 9–10 m tall in the open, grown for its juicy fruit. It is sensitive to frost, so outside frost-free regions it is grown in a pot that winters indoors or in a greenhouse; the fruit takes about a year from flower to ripe.

Quick facts

Type	Fruit tree
Family	Rutaceae
Light	Full sun
Soil pH	5.5–6.5
Frost	does not tolerate frost
Sowing to harvest	1095 days
Where it grows	Greenhouse, Open ground, At home

When to plant

Planted as a young plant from a nursery while it is dormant — in early spring before the buds open, or in autumn after leaf fall.

Harvest from December to March (northern hemisphere).

Care

Greenhouse

Stage	Watering	Temperature	Feeding
Growth	every 7 days	13…29 °C	nitrogen, at the start of the stage; nitrogen, 14 days into the stage; nitrogen, 28 days into the stage; nitrogen, 42 days into the stage
Flowering	every 7 days	13…29 °C	nitrogen, at the start of the stage; nitrogen, 14 days into the stage
Fruiting	every 7 days	13…29 °C	nitrogen, at the start of the stage; nitrogen, 14 days into the stage; nitrogen, 28 days into the stage; nitrogen, 42 days into the stage; nitrogen, 56 days into the stage; nitrogen, 70 days into the stage; nitrogen, 84 days into the stage
Harvest	every 14 days	10…18 °C	balanced (NPK), at the start of the stage
Winter rest	every 14 days	10…18 °C	balanced (NPK), at the start of the stage; balanced (NPK), 30 days into the stage; balanced (NPK), 60 days into the stage; balanced (NPK), 90 days into the stage

Open ground

Stage	Watering	Temperature	Feeding
Growth	every 14 days	—	nitrogen, at the start of the stage
Flowering	every 14 days	—	—
Fruiting	every 14 days	—	nitrogen, at the start of the stage
Harvest	every 14 days	—	—
Winter rest	every 42 days	—	—

At home

Stage	Watering	Temperature	Feeding
Growth	every 7 days	13…29 °C	nitrogen, at the start of the stage; nitrogen, 14 days into the stage; nitrogen, 28 days into the stage; nitrogen, 42 days into the stage
Flowering	every 7 days	13…29 °C	nitrogen, at the start of the stage; nitrogen, 14 days into the stage
Fruiting	every 7 days	13…29 °C	nitrogen, at the start of the stage; nitrogen, 14 days into the stage; nitrogen, 28 days into the stage; nitrogen, 42 days into the stage; nitrogen, 56 days into the stage; nitrogen, 70 days into the stage; nitrogen, 84 days into the stage
Harvest	every 14 days	10…18 °C	balanced (NPK), at the start of the stage
Winter rest	every 14 days	10…18 °C	balanced (NPK), at the start of the stage; balanced (NPK), 30 days into the stage; balanced (NPK), 60 days into the stage; balanced (NPK), 90 days into the stage

Growing notes

Light

Give it the brightest spot you have, at least 6–8 hours of direct sun, such as a south or south-west window; it can stand outdoors in summer once nights stay above 10 °C.

Soil

Use a quick-draining, slightly acidic potting mix (pH 5.5–6.5) in a pot with good drainage holes; never leave the pot standing in water.

Care

Water thoroughly when the top 5–7 cm of the mix are dry, which in hot weather can mean almost daily; in winter let the surface dry partly before watering. From spring to early autumn feed every two weeks with a nitrogen-rich citrus feed with trace elements, and in winter switch to a balanced winter citrus feed. Keep it at 13–29 °C while growing and rest it at about 10–18 °C in winter; bring it in before nights drop below about 10 °C. Taste the fruit to judge ripeness, since the peel colour is not a reliable sign. Thin branches in February and pinch back new shoots in summer.

How to tell it is ripe

The fruit has reached full size with a bright orange to yellow-orange skin.
Colour alone is not a reliable sign; ripe oranges often keep green patches or stay green in warm climates.
Taste one fruit; tasting is the only sure way to tell a citrus fruit is ripe.
Oranges do not ripen or get sweeter once picked, so leave them on the tree until they taste sweet.
Cut the orange off with secateurs together with a short piece of stalk, and pick as needed because ripe fruit keeps well on the tree.

Sources

Figures checked against these sources.