Description:
Kumquats (Citrus japonica) are beautiful ornamental trees with miniature fruits that closely resemble the orange (Citrus x sinensis). Because the sweetly fragrant white flowers appear on the trees from spring and through summer, and the fruits mature in late winter, holding well on the tree, kumquats are grown for their ornamental value as well as their culinary uses.
This small, slow growing fruit tree is very popular in China, where the term “kumquat” actually means 'golden orange' in Mandarin, in reference to the small orange fruits. With its sweet rind and tangy flesh the fruit can be eaten skin and all. The branches bear very few thorns and the glossy evergreen leaves look good all year round, and when the clusters of dainty white blossoms open they fill the air with a sweet scent.
Where do kumquats originate from?
The kumquat is native to Southern China, with references to the plant appearing in Chinese literature from around the 12th century. The plants have been cultivated for centuries in other parts of East Asia, South Asia, and Southeast Asia, and are a symbol of good luck in several Asian cultures.
In 1846 kumquats were introduced into Europe by Robert Fortune, collector for the London Horticultural Society, and today they are cultivated across the world, but there is still confusion around the classification of some species. For example, the Round Kumquat (Citrus japonica), also called the “Marumi Kumquat”, was first described by Carl Peter Thunberg in 1780 as (Fortunella japonica) but is now often classified as (Citrus japonica). Different classifications have alternatively assigned kumquats anywhere from a single species, Citrus japonica, to numerous species representing each cultivar.
Kumquat 'Nagami' Picture courtesy Just Berry PlantsKumquat Varieties
Today kumquats are grafted to improve vigour and pest resistance. Dwarf varieties are created by grafting the growing plant onto a dwarf rootstock. This produces smaller plants but does not affect the size or quality of the fruit.
Kumquat Nagami, Oval Kumquat (Citrus margarita)
The most distinctive features of Kumquat Nagami is its oblong or oval fruit of good size, and the deep colour and pronounced flavour of both the flesh and the rind, though the rind oil is somewhat more pronounced than in other kumquats.
Nagami is a compact and bushy tree, typically growing 1.8 to 3.5m tall making it suitable for container growing or small gardens. In the ground it can grow to a height of between 2 and 4m. If pruned annually it can remain between 1 and 1.2m tall, making it an excellent choice to grow in a container or small garden.
Kumquat Dwarf Meiwa, Round Kumquat (Citrus japonica ‘Meiwa’)
Dwarf Meiwa grows to a height of between 1.5 and 2 metres and produces small round fruits with thin, deliciously sweet skins. If pruned annually it can remain between 1 and 1.2m tall, making it an excellent choice to grow in a container or small garden.
If you are growing it in a pot, choose one at least 50cm in diameter and depth. Repot the tree every 2-3 years to refresh the soil and accommodate growth. Dwarf kumquat trees will benefit from 2 to 5cm of pine bark mulch. The mulch protects the roots from UV damage and drying out, retains moisture, and maintains an optimal pH. Do not let the mulch touch the plant stem, as it may cause infection or rot.
Members can click here to read my article: “How to grow fruit trees in small spaces”
Health Benefits:
Kumquats have lots of vitamin C, fibre, antioxidants, and a little vitamin A. They are free of cholesterol and low in sodium, making them a really healthy and tasty snack.
Preserved Kumquats Picture by Jean Weber from flickrIn the Kitchen:
Ripening in winter, the best tasting kumquat varieties have edible skins and flesh, and are sweet enough to eat fresh, served with salads, or juiced for a refreshing drink. They are renowned for making wonderful marmalade, and can be candied and preserved whole.
Kumquats can be used in various culinary applications, as their sweet and tangy flavour makes them a great addition to many sweet or savoury dishes.
Search for Kumquat recipes online and be inspired by what you can do with these little fruits.
In the Garden:
Kumquats are valuable garden ornamentals that can be planted in garden beds or pots. Standard plants look wonderful planted in tubs, and the new compact dwarf cultivars grow beautifully in pots or in the ground, and can be used in even the tiniest of gardens.
In cultivation in the United Kingdom Citrus japonica has gained the Royal Horticultural Society's Award of Garden Merit.
Members can click here to read my article “How to grow fruit trees in small spaces”
Kumquat 'Meiwa' Picture courtesy Just Berry PlantsCultivation:
Do you need pollinators for Kumquats?
Kumquat trees are self-pollinating, so you only need one tree to bear fruit.
Are Kumquats hardy to cold?
Unlike other citrus fruits like oranges, established kumquats are known to withstand winter temperatures as low as -7°C. However, temperatures between -3°C to -5°C are more acceptable, and if they drop lower it is advised that you protect the plants, as extreme cold will set them back.
In cold regions you can grow kumquats in a very sheltered part of the garden, or in large pots on warm patios. Cover young plants in winter with a frost protection cover until they are established.
Do Kumquats grow in coastal gardens?
Kumquats do well in coastal gardens if planted in a position sheltered from strong winds.
How much sun do Kumquats require?
Citrus trees grow, flower and bear best in full sun positions, but will take some shade.
What soil type do Kumquats need?
Kumquats will adapt to most garden soils that drain well, as they do not like waterlogged roots. They do not do well in saline (salty) soils, growing well in fertile soils with a neutral pH range from 6 to 8.
Plant your Kumquat tree at the proper depth
Planting citrus at the proper depth is the most important factor. Plant the tree too low and the trunk will stay wet, and this will encourage bark diseases. Plant it too high and the root ball will dry out too quickly and not enough moisture will get to the tree. Dig the hole, and before removing the plant from its nursery bag, check to see that the planting depth will be at the same level as it is currently in the bag, then remove and plant.
How to feed kumquat trees?
Young citrus trees must be planted in deeply dug soil with added compost but no fertiliser. Newly planted trees should only be fertilised when they start showing new growth.
Established trees require moderately heavy nutrients, and even on very fertile soils they will require feeding after a few heavy crops. Feed three times a year in July, December and March with a balanced fertiliser that has high nitrogen and medium potassium levels, 8:1:5 is fine for the home gardener. Mature citrus trees should receive enough nitrogen to provide good, healthy leaf coverage, but not excessive leaf growth.
In addition, give established trees 75g of Epsom salts (magnesium sulphate) three times a year.
Never apply fertiliser close to the trunk and spread it uniformly on the soil surface under the tree canopy, extending out to slightly to beyond the drip line. Water it in thoroughly.
Potted specimens will need more frequent feeding than those growing in the soil.
How much water do Kumquats need?
How often you need to water your kumquats will depend on the composition of the soil, how well it drains, and rainfall. Newly planted trees will require regular watering until they are established.
Once established, the trees may tolerate some drought, but the quality of the fruit will be affected. Be careful not to overwater, as overwatering can be just as much of a problem as not watering enough.
During the growing season you can water your trees thoroughly and then allow them to dry out before re-watering. During the summer months, established trees growing in the garden can be watered deeply about every 7 to 10 days, and in winter every 2 to 3 weeks. Water well during dry, warm weather, or they may prematurely drop their flowers or developing fruit.
Potted specimens will need to be checked more frequently for watering than those growing in the ground.
Harvesting:
The flowering season for kumquats is summer and the fruits mature in late winter, holding well on the tree. They must be allowed to ripen on the tree before being picked, which may take weeks, and the only way to know if they’re ready is to sample one. The fruits will begin to fall from the tree when they are overripe.
Pruning:
Kumquat trees don’t require pruning except to cut away any long, skinny branches growing straight up and all damaged or dead wood, or if you just want to keep the plant smaller. Prune after fruiting, and before it blooms in spring.
