The scientific name for the species is Ziziphus jujuba. Both the tree and fruit are commonly referred to as ‘jujube’, ‘red date’, and ‘Chinese date’.
The plant is a small deciduous tree or shrub that grows to 5 to 10m high. The branches are usually thorny, but almost thornless cultivars are known. The fruit is known botanically as a drupe, i.e. a stone fruit. The single hard stone is similar to an olive stone.
The fruit can vary widely in size and shape depending on the cultivar—from cherry-size to plum-size and from round to elongate in shape. The thin edible skin surrounds whitish flesh when immature, and ripens through a yellow-green stage with mahogany-coloured spots to a fully ripened, entirely red-brown fruit. After this stage the fruit begins to soften and wrinkle, and when fully dry becomes naturally sweet with a 20% natural sugar content.
The fruit is prized both as a snack and for traditional Chinese and Korean medicine. Claimed properties include stress relief, antifungal, antibacterial, antiulcer, anti-imflammatory, and sedative relief. They are also attributed to aid hypotension, cardiac health, stimulation of the immune system, and wound healing, and to counter a lack of fertility. There is clinical evidence that red dates help relieve chronic constipation and neonatal jaundice, while a leaf extract showed anti-obesity activity in rats.
Red dates are highly nutritional, containing vitamin A, thiamine, riboflavin, riboflavin, niacin, vitamin B6 (raw only), vitamin C, calcium, iron, magnesium, phosphorus and potassium. Carbohydrate content is 20.23% by weight when raw and 73.60% when dried. Protein content is 1.2% by weight when raw and 3.7% when dried. Fat content is 0.20% when raw and 1.10% when dried.
Red dates can be eaten raw (between the yellow-green and fully red stages), dried, and as a candied dry preparation. Juice, wine, vinegar and preserves are other uses for the fruit.
The Chinese red date was domesticated in South Asia by 9000 BC, and over 400 cultivars now exist. The exact natural distribution of the plant is not known, but is believed to be southern Asia, between Lebanon, Iran, Pakistan, India, Bangladesh, Nepal, the Korean peninsula, and southern and central China.
The tree is very hardy and thrives in warm to hot, dry climates. It prefers a full sunny position and does not like to be in the shade of other trees. It can tolerate temperatures down to about -30Â°C during winter dormancy and high temperatures in summertime. A small winter chill is the minimum needed for fruit set, and it is a lack of sun and heat more than the cold that reduces fruiting ability.
It requires less water and can handle more salt than most fruit crops, and tolerates drought conditions. The tree does still require regular watering during summer if it is to produce a quality crop.
Preferred soil pH is 5 to 6 4, but the Chinese red date can handle alkaline soils as well. The tree tolerates a range of soils, but does best in sandy well-drained soils and least well in heavy poorly draining soils.
The tree is self-fertile and flowers from November to December, with fruit appearing eight weeks later. Dates are produced in the first year of production. The crop does not ripen simultaneously and can be picked from one tree over eight weeks. Fruit not picked fresh can be left on the tree to dry naturally before being picked.
Unripe fruit will not ripen once picked. Ripe fruit will keep for a week at room temperature, and tree-dried fruit will keep indefinitely without the need for a sulfur preservative as with e.g. apricots.
The trees do not appear to require much fertiliser to do well, though a light broadcast of a balanced fertiliser during the growing season will increase growth.
Trees should be placed 4 to 5 metres apart to ensure exposure to full sun for best production. 30 to 40 kilograms of red dates can be harvested from a tree in full production.