Were Oranges Originally Green? Why Ripe Ones Can Be Too

Next time you are in the fruit section in summer, pick up a Valencia orange and look near the stem. You may find a patch of green. It is easy to assume the orange was picked too early, but with a Valencia that green can mean something quite different: the fruit can be fully ripe and sweet even though its skin has turned green again. That small patch of green leads to a surprisingly tangled story of plant pigments, temperature, citrus evolution and even the history of the English language.

So were oranges originally green? In many warm climates, ripe oranges really can stay green, and even in cooler ones a ripe orange can sometimes turn green again. The bright orange we think of as natural comes from the weather as much as from ripeness.

Green while they grow

An orange’s skin contains several pigments, including green chlorophyll and yellow-orange carotenoids. While the fruit is developing, chlorophyll gives the peel its green colour, and as the fruit matures and the chlorophyll breaks down, the yellow and orange pigments show through. The catch is that an orange does not have to turn bright orange to be ripe. Temperature has a big influence on what happens to the peel. In climates with cool periods, the chlorophyll breaks down and the familiar orange appears, but in warmer conditions it can stay in the rind, leaving perfectly ripe fruit green or greenish-orange. The flesh inside can be sweet and mature while the peel is still full of green pigment, which is why colour alone is a poor guide to whether an orange is ready to eat.

A warm-climate fruit with a tangled family tree

The orange’s history is more complicated than the old line that it is simply a cross between two ancient fruits. A major 2018 study in Nature analysed the genomes of 60 types of citrus and traced the whole citrus family to the southeast foothills of the Himalayas, in a region taking in parts of Assam, northern Myanmar and western Yunnan. It also found that Australia’s native limes, such as finger limes, came from a later wave of citrus that crossed the Wallace line into Australia in the early Pliocene, as Australia’s Science Channel reported.

The sweet orange’s own origin is even more intricate. Earlier genetic studies pointed to pomelo and mandarin ancestry, but a 2025 study in Nature Genetics used high-resolution, phased genome analysis to propose that sweet orange arose from a cross between an ancient sour orange and a Ponkan-like mandarin. As a Nature Plants summary explains, the team backed this up by crossing the two and producing hybrids that closely resembled commercial sweet oranges, and sour orange itself probably descends from an even older mandarin and pomelo cross. So the safest description is that the sweet orange is an ancient hybrid with several citrus lineages in its background. For the colour mystery, what matters is that it evolved in a warm part of Asia, where the peel of ripe fruit could easily stay green.

What cold does to the peel

Think about what happens to many tree leaves in autumn. The green chlorophyll breaks down and reveals other pigments that were there all along. Something very similar happens in citrus peel. As produce specialist PRO*ACT explains, cold winter temperatures suppress the chlorophyll, letting the deep orange colour show. So an orange grown somewhere with cool nights develops the bright peel shoppers expect, while one grown in consistently warm conditions may keep much more of its green even when the flesh is ripe. Green does not automatically mean unripe, and orange does not automatically mean perfectly ripe. The colour of the skin records the weather as much as the fruit’s development.

The summer oranges that turn green again

Valencias are where this gets really interesting. They are a late-season orange with an unusual ability to stay on the tree long after they ripen, which means they are often still hanging there as the weather warms up. The University of California’s Integrated Pest Management program explains that because Valencias hold so well on the tree into summer, chlorophyll returns to the rind and gives it a greenish colour, a change called regreening. It describes regreening as mainly aesthetic: the fruit still has good quality and is, in its words, very sweet and juicy. In California, these greenish oranges are even sold as “Summer Greens”. PRO*ACT adds that the green usually appears near the stem, may help protect the peel from sunburn, and is more common on fruit tucked in among the leaves. So the green patch on a summer Valencia is not a sign it was picked too early. Cut one open, and the flesh tells the real story.

Why shop oranges look so orange

There is one more reason supermarket oranges usually look the way we expect: some citrus is degreened after harvest. Because most of us associate green peel with unripe fruit, packers place oranges in a temperature and humidity-controlled room with measured amounts of ethylene gas. Ethylene is a hormone that plants produce naturally, and PRO*ACT explains that it speeds up the breakdown of chlorophyll so the peel turns from green or yellow to orange, without changing anything else about the fruit. In the United States, some oranges are also coloured with an approved dye, Citrus Red No. 2, as Garden.eco notes. The orange you see in a shop, in other words, reflects the variety, the growing conditions, the temperature and sometimes the handling after picking, not just what happened on the tree.

The fruit came before the colour

The English word orange originally meant the fruit, not the colour. Before it arrived, English speakers described the shade with words such as yellow-red, which in Old English was geoluhread, as EnglishClub explains, or saffron. The fruit then lent its name to the colour.

Those dates come from Wikipedia’s history of the word, and the history of the colour adds that it took until the 17th century for “orange-coloured” to give way to plain “orange” as an everyday colour word.

There is a neat clue left behind in the name. Spanish still says naranja, with the original n at the front, but in French the n disappeared. The usual explanation is that “une narange” was heard as “une orange”, with the n drifting across to the word before it, the same kind of slip that turned “a napron” into “an apron” in English. The name of the fruit still carries the mark of its journey between cultures.

A green patch worth a second look

So, were oranges originally green? Every orange starts out green, ripe ones can stay green in warm climates, and a summer Valencia can even turn green again after it has ripened. The orange colour we take for granted is a product of cool weather, and in the shops often a little help after harvest, while the name of the colour itself was borrowed from the fruit. Next time you find a green patch on a Valencia, you are not looking at a mistake. You are looking at something the supermarket usually hides: the colour of the peel is not a perfect measure of what is happening inside.

If you enjoy this kind of everyday food mystery, my post on whether something is a fruit or a vegetable tackles another one, and if colours are more your thing, I have also asked whether black and white are actually colours.

Sources

• Wu et al: Genomics of the origin and evolution of Citrus, Nature (2018), via the Joint Genome Institute
• Australia’s Science Channel: Finally, we know where citrus fruit came from
• Origin and de novo domestication of sweet orange, Nature Genetics (2025)
• Nature Plants: Re-domestication of sweet orange (2025)
• UC Statewide IPM Program: Regreening
• The Produce News: PRO*ACT crop update, citrus regreening and degreening
• Garden.eco: Green oranges
• Wikipedia: Orange (word)
• Wikipedia: Orange (colour)
• EnglishClub: The colour orange was named after the fruit