The jujube is native to climates with a yearly temperature range from around -5°C to 50°C, but can survive winters that get down to -30°C.
While growth in areas with cool summers can be very slow, the tree thrives in hot, dry environments with long summers and warm nights. Heat is crucial for flower production and fruit development, and jujubes require a range of at least 20°C to 25°C during the flowering stage for fruit to set. Unlike most fruit trees, jujubes have a very long period of flowering, often over a few months. If temperatures are too cool for the first flush of flowers to set fruit, later flowers usually will as the weather warms.
While summers can’t be hot enough, the tree does need around 200-400 hours of exposure to temperatures below 7°C over winter during dormancy. This is called its chilling requirement, and ensures vernalisation (the induction of the flowering process) occurs in spring.
Jujube trees flower later than other fruit trees, from November on, and are thus unaffected by late frosts that can devastate other fruit crops.
Many jujubes in China grow in loess, a fertile and porous yellow-brown soil comprised of around 50% wind-blown silt, 10-20% clay and the remainder sand and other silt. But jujubes are very hardy and can grow in anything from sand to clay, and even in areas of high rock or gravel content, so long as enough soil is present for roots to take hold. Jujube trees to this day grow in the mountainous and rocky regions of northern China.
Of course the poorer the soil the longer it will take for a tree to establish. Jujubes grow best in a deep, well-drained soil of medium texture, such as loams and sandy loams, and grow worst in heavy clay and other poor-draining soils.
Jujubes can grow in soils with a pH range from 4.5 (acidic) to 8.4 (alkaline). For comparison, the loess in China varies from pH 7 (neutral) to pH 9.5 (quite alkali).
Jujubes need to be watered regularly as with any newly planted fruit tree for the first few years, but once established are more drought-hardy than those same fruit trees under similar conditions. They are the last to wilt on hot, dry days. The jujube can survive on as little as 200 mm rainfall a year, but will require at least 508 mm a year for fruit production, whether rainfall or irrigation.
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