Fact-check log
Every claim on this site was checked against a cached copy of a named page on 14 November 2026. Regexes have to match the source text. Where two good sources disagree, the disagreement stays visible.
What is a kumquat called, botanically?
The RHS lists the kumquat as Citrus japonica, with an Award of Garden Merit, and describes oval orange fruits with sour flesh and a sweet rind. Britannica treats the kumquat as a separate genus, Fortunella, and names the common oval (Nagami) kumquat Fortunella margarita. We report both wordings and do not pick a single scientific name as the last word.
How big is a lemon tree?
Britannica gives 3-6 metres (10-20 feet) if a lemon plant is not pruned, for orchard trees. The RHS, writing for UK gardeners growing citrus in pots, says most citrus form attractive small trees or shrubs less than 1.5m (5ft) tall. Those are different growing systems, so both figures stand.
| Claim | Source |
|---|---|
| Citrus plants won't reliably survive winters outdoors, even in the warmest parts of the UK. | RHS, How to grow citrus |
| When grown in containers they can be kept in a greenhouse, conservatory or glazed porch over winter, then moved outdoors in summer into a sunny, sheltered spot. | RHS, How to grow citrus |
| Growing citrus as houseplants is not ideal long term, as most prefer a cool spell in winter and a more humid atmosphere than centrally heated homes usually provide. | RHS, How to grow citrus |
| The fruit ripens slowly, for up to a year, so plants often carry flowers and fruit at the same time. | RHS, How to grow citrus |
| Most citrus form attractive small trees or shrubs less than 1.5m (5ft) tall, so are ideal for growing in containers. | RHS, How to grow citrus |
| If you are new to growing citrus fruit, the RHS says it is best to start with one of the easier types, such as lemons. | RHS, How to grow citrus |
| Certain varieties of kumquats, limes and calamondin oranges can also be fairly straightforward. | RHS, How to grow citrus |
| Look for varieties with an RHS Award of Garden Merit (AGM), which shows they performed well in trials. | RHS, How to grow citrus |
| Most commercially sold citrus plants are grafted to ensure they fruit at an early age. | RHS, How to grow citrus |
| Ungrafted plants may take up to ten years to fruit. | RHS, How to grow citrus |
| Citrus plants are self-fertile, meaning you only need one plant to produce fruit. | RHS, How to grow citrus |
| Some lemons, for example, will be fine as low as 5 degrees C (42 degrees F). | RHS, How to grow citrus |
| Kumquats often need 7 degrees C (45 degrees F) or more. | RHS, How to grow citrus |
| Limes and grapefruits should be kept above 10 degrees C (50 degrees F). | RHS, How to grow citrus |
| Calamondin oranges need at least 13 degrees C (55 degrees F). | RHS, How to grow citrus |
| In summer, water citrus plants regularly, ideally with rainwater. | RHS, How to grow citrus |
| Overwatering in winter is one of the commonest problems, so err on the dry side, and never leave pots standing in water, as this can cause the roots to rot. | RHS, How to grow citrus |
| From late March to October, apply summer citrus feed, which is high in nitrogen. Then from November to mid-March, switch to a more balanced winter citrus feed. | RHS, How to grow citrus |
| The RHS notes that calamondins make attractive plants and the fruit is great in preserves. | RHS, How to grow citrus |
| The RHS describes the kumquat (Citrus japonica, AGM) as having oval orange fruits with sour flesh and a sweet rind. | RHS, How to grow citrus |
| The RHS says a plant about 1m (3ft) tall should be allowed to carry no more than 20 fruits at one time. | RHS, How to grow citrus |
| Only kumquats, with their much smaller fruits and bushy style of growth, can successfully carry a heavy crop without any need for thinning. | RHS, How to grow citrus |
| The RHS lists a huge range of citrus plants to choose from, including lemons, oranges, mandarins, limes, grapefruits, kumquats, limequats, calamondin oranges, tangelos and citrons. | RHS, How to grow citrus |
| Citrus is a genus of plants belonging to the rue family (Rutaceae), yielding pulpy fruits covered with fairly thick skins. | Encyclopaedia Britannica, Citrus |
| Economically important plants in this group include the lemon, lime, sweet orange, sour orange, tangerine, grapefruit, citron and shaddock. | Encyclopaedia Britannica, Citrus |
| Yuzu is the most cold-resistant of all citrus fruits, capable of growing at high altitudes at temperatures just above freezing, and is most commonly associated with Japan and Japanese cuisine. | Encyclopaedia Britannica, Citrus |
| Citrus plants are typically evergreen trees or shrubs with glossy oval-shaped leaves; many species have thorns. | Encyclopaedia Britannica, Citrus |
| The flowers are usually white with five petals and are very fragrant. | Encyclopaedia Britannica, Citrus |
| The fruits are a type of modified berry known as a hesperidium, and the flesh is divided into segments packed with tiny juice-filled vesicles. | Encyclopaedia Britannica, Citrus |
| The peel, or rind, of the fruits is leathery and studded with oil glands. | Encyclopaedia Britannica, Citrus |
| The lemon (Citrus x limon) is a small tree or spreading bush of the rue family and its edible fruit. | Encyclopaedia Britannica, Lemon |
| Citric acid may amount to 5 percent or more by weight of the lemon's juice, which is also rich in vitamin C. | Encyclopaedia Britannica, Lemon |
| The lemon was introduced into Spain and North Africa sometime between the years 1000 and 1200 CE. | Encyclopaedia Britannica, Lemon |
| In 1494 the fruit was being cultivated in the Azores and shipped largely to England. | Encyclopaedia Britannica, Lemon |
| The lemon was thought by Linnaeus to be a variety of citron (Citrus medica), though it is now known to be a separate hybrid species. | Encyclopaedia Britannica, Lemon |
| The lemon plant forms an evergreen spreading bush or small tree, 3-6 metres (10-20 feet) high if not pruned. | Encyclopaedia Britannica, Lemon |
| The fruit is oval with a broad, low, apical nipple and forms 8 to 10 segments. | Encyclopaedia Britannica, Lemon |
| The white spongy inner part of the peel, called the mesocarp or albedo, is nearly tasteless and is the chief source of commercial grades of pectin. | Encyclopaedia Britannica, Lemon |
| The relatively cool, equable climatic zones of coastal Italy and California are especially favourable for lemon cultivation. | Encyclopaedia Britannica, Lemon |
| Lemon trees usually bloom throughout the year, and the fruit is picked 6 to 10 times a year. | Encyclopaedia Britannica, Lemon |
| The fruit is usually picked while still green and, after curing, may be kept three months or more in storage. | Encyclopaedia Britannica, Lemon |
| Young lemon trees reach bearing age as early as the third year after planting, and commercial crops may be expected during the fifth year. | Encyclopaedia Britannica, Lemon |
| The average orchard yield per tree is 1,500 lemons a year. | Encyclopaedia Britannica, Lemon |
| A lime, in Britannica's wording, is any of several species and hybrids of trees and shrubs of the genus Citrus (family Rutaceae), widely grown in tropical and subtropical areas for their edible acidic fruits. | Encyclopaedia Britannica, Lime |
| The Persian lime (Citrus x latifolia) is one of the most common commercial varieties, though the smaller key lime, or Mexican lime (C. x aurantifolia), is also economically important in many places. | Encyclopaedia Britannica, Lime |
| The tree seldom grows more than 5 metres (16 feet) high and if not pruned becomes shrublike. | Encyclopaedia Britannica, Lime |
| The fruit is usually about 3 to 4 cm (1 to 1.5 inches) in diameter, oval to nearly globular, often with a small apical nipple, and the peel is thin and greenish yellow when ripe. | Encyclopaedia Britannica, Lime |
| Most limes exceed lemons in both acid and sugar content. There are, however, some varieties so lacking in citric acid that they are known as sweet limes. | Encyclopaedia Britannica, Lime |
| Wild limes probably originated in the Indonesian archipelago or the nearby mainland of Asia. | Encyclopaedia Britannica, Lime |
| Arabian traders may have taken limes, as well as lemons, from India to the eastern Mediterranean countries and Africa about 1000 CE. | Encyclopaedia Britannica, Lime |
| Christopher Columbus took citrus seeds, probably including limes, to the West Indies on his second voyage in 1493. | Encyclopaedia Britannica, Lime |
| Limes contain vitamin C (ascorbic acid) and were formerly used in the British navy to prevent scurvy, hence the nickname "limey," in Britannica's wording. | Encyclopaedia Britannica, Lime |
| The fruit and leaves of the Thai lime, or makrut lime (C. hystrix), add distinctive flavour to the cuisines of Southeast Asia. | Encyclopaedia Britannica, Lime |
| Finger limes (C. australasica), native to Australia, are noted for their discrete juice vesicles, sometimes called "lime caviar." | Encyclopaedia Britannica, Lime |
| Britannica treats the kumquat as genus Fortunella, evergreen shrubs or trees of the family Rutaceae, grown for their tart orange fruits. | Encyclopaedia Britannica, Kumquat |
| Native to eastern Asia, these small trees are cultivated throughout the subtropics. | Encyclopaedia Britannica, Kumquat |
| Kumquat fruits may be eaten fresh, or they may be preserved and made into jams and jellies. In China they are frequently candied. | Encyclopaedia Britannica, Kumquat |
| Kumquat plants reach about 2.4 to 3.6 metres (8 to 12 feet) high. | Encyclopaedia Britannica, Kumquat |
| The bright orange-yellow fruit is round or oval, about 2.5 cm (1 inch) in diameter, with mildly acid juicy pulp and a sweet, edible, pulpy skin. | Encyclopaedia Britannica, Kumquat |
| The oval, or Nagami, kumquat (Fortunella margarita) is the most common species, native to southern China. | Encyclopaedia Britannica, Kumquat |
| The egg-shaped Meiwa kumquat (F. crassifolia) has both pulp and rind that are sweet, and is widely grown in China. | Encyclopaedia Britannica, Kumquat |