Flowering
Jujube trees bloom in early summer and fruit ripens in late summer/autumn but flowering time can vary at different locations and depends on cultivar and climate. Flowering of jujubes generally occurs over an eight week period in summer. The trees flower from November to December, with fruit starting to ripen at the end of February.
Flowers occur in the axils of the leaves on the current bearing shoots. Flowers are short stemmed, light green-yellow and 3–10mm in diameter. Flower buds complete differentiation and development to mature fruit within a single growing season.
While most cultivars are self-fertile, pollination can be enhanced through the introduction of bees. Pollen is sticky so wind pollination is ineffective. Pollen viability is low in most cultivars. Jujube trees typically have abundant flowering but low fruit set. Heavy fruit drop occurs after fruit set, caused by lack of fertilisation or degeneration of the ovule. Soil moisture stress, low relative humidity, lack of sunlight and strong winds during fruit maturity can also lead to fruit drop.
Measures to improve fruit set include:
- trunk girdling during flowering
- heading back current year shoots
- keeping bees in the orchard during the flower season
- two to three sprays of 10–20ppm gibberellic acid or 0.2% borate during flowering.
Fruit development
The time for fruit maturation varies among cultivars from 60 to 145 days. Fruit development is slightly longer in warmer climates and shorter in cooler climates.