(Image credit: Surapong Tanachotrungruang)

You may call it a clementine, but that citrus fruit – like many of its brethren regardless of marketing name – is in fact a mandarin. All loose-skinned, cold-hardy citrus fruit are mandarins (Citrus reticulata). 

If you have one of these fruit trees in your home orchard, you’ll definitely want to understand the clementine growing season and when and how to harvest these sweet citrus fruit.

Mandarins, Clementines, and Tangerines

Let’s start out with the botany: what Americans call tangerines are actually mandarins -- they are called mandarins everywhere else around the globe. The term “tangerine” appears to have been a marketing ploy for reddish-orange varieties of mandarins. Today it is used only by Americans and has no botanical significance.

Clementines, on the other hand, are a variety of common mandarins. The term is used to refer to several varieties of common mandarin including Clemenules, which may have been the origin of the name. Regardless of the variety, mandarins are all harvested in the same way.

When to Pick Mandarin Oranges

It’s always nice when there is a hard and fast rule about when a fruit will be ripe and ready to harvest. This is not the case with citrus. 

When it comes to picking tangerines or any other citrus fruit, there is no such thing as “tree ripe.” The fruit moves from immature to mature then to overly-mature stages over several months. The optimal harvest period can extend from November through January. 

So how to determine when to harvest clementines? The only way for a gardener to determine the maturity of citrus fruit in a home orchard is to taste the fruit. What about fruit color? This won’t help you, since the color development does not synchronize with the sugar development. Some fruits have fully colored rinds well before they are ripe, while others are green even though deliciously ready to eat. 

Do mandarin oranges ripen after picked? They do not. Citrus fruits do not change after they are removed from the tree other than to slowly dry out. This means that the taste test is an essential precursor to the harvest. Note that mandarin fruit is often most delicious once it’s hit with cold temperatures, since this releases the sugars in the flesh. 

How to Pick Clementines

The best way to harvest your mandarin oranges, including clementines, is to put on garden gloves and hand-pick them. You can snap the fruit off the tree or, if you prefer, clip them off with pruners. 

Note that the fruit holds better on the tree than in storage, so just because one fruit is ripe does not mean you have to harvest everything the same day. Unless the fruit is damaged by a freeze, mandarins should keep for several weeks or longer on the tree.

Teo Spengler

Teo Spengler has been gardening for 30 years. She is a docent at the San Francisco Botanical Garden. Her passion is trees, 250 of which she has planted on her land in France.