The Jujube Tree Growth Cycle

Jujube trees go through many stages over a yearly cycle. As they leave dormancy around August/September, the sap begins to flow, buds erupt, and leaves grow. Roots grow and branches appear. Flower buds begin appearing about a month later, from September/October through to December, depending on cultivar and location. Fully developed flowers when pollinated become fertilised, and develop into fruit. The fruit grow from December on, and reach maturity anywhere from late February to March/April, again depending on cultivar and location.

After a tree has produced its fruit it begins to slow down and prepare for winter. The sap retreats and the leaves turn yellow and fall off. Young fruiting branches will also fall off — a peculiarity of jujubes not shared by other fruit trees. The tree enters dormancy over winter and the cycle begins anew.

A tree requires different nutrients at different times throughout this cycle, to ensure the needs of each stage is met. Leaves have different needs to roots, and flowers and fruit have different needs again. It is important to ensure those requirements are met at the right times so as to maximise tree health and fruit production.

Here we’ll step through these nutrients, and where they feature in this cycle. The next post will discuss some common formulations designed with the backyard fruit enthusiast in mind.

Essential Macronutrients

Macronutrients are the nutrients needed in larger quantities. There are six macronutrients essential for all plants’ growth and survival.

Nitrogen (N)
Nitrogen is essential for leaf and stem growth as well as chlorophyll production. Chlorophyll is essential in photosynthesis and is also the pigment responsible for the green colour of leaves. Pale yellow-green leaves can be an indicator of low nitrogen availability. But too much nitrogen in the soil can lead to a potassium deficiency and later fruiting problems.

Nitrogen is a nutrient a tree needs mostly at the beginning of the cycle to feed leaf growth and branch development as it leaves dormancy and buds begin to break, and through its main growth period prior to fruit set.

Phosphorus (P)
Phosphorus strengthens roots, boosts resilience to pests and diseases, and helps trees get through harsh winters by strengthening tissues. It is also needed for flowering and fruit production, and enhances fruit flavour. Too little phosphorus stunts growth and causes premature leaf fall — leaves take on a bluish-green colour before turning purplish or bronze with brown edges. Too much phosphorus on the other hand can cause zinc, copper, iron or manganese deficiencies.

Potassium (K)
You may know this as potash. Potassium too is essential for vigorous growth that is resistant to pests and diseases. It also strengthens plants and aids in early growth and water-retention. Potassium deficiencies show as stunted growth with leaves growing very close to each other — these leaves eventually develop brown tips and edges, which curl. Too much potassium can lead to calcium and magnesium deficiencies.

Magnesium (Mg)
Magnesium increases the uptake of phosphorus and is essential for chlorophyll production. A magnesium deficiency can cause yellowing leaves — this is why epsom salts (magnesium sulfate) is a traditional remedy for this symptom. Too much magnesium can cause a calcium deficiency however.

Calcium (Ca)
Calcium is essential for root growth, and the growth and development of cell walls in general. This strengthening of plant tissues assists in pest and disease resilience. Calcium deficiency causes poor root development and distorted, brown, leaves.

Sulfur (S)
Sulfur is another nutrient important for chlorophyll development, as well as helping resist disease. A sulfur deficiency results in tip bud death and the slow growth of small, round, stiff, brittle leaves that drop off.

Essential Micronutrients

Micronutrients are needed in much smaller (trace) quantities.

Iron (Fe)
Iron is essential for chlorophyll formation and oxygen transfer. An iron deficiency leads to yellowing leaves with green veins.

Manganese (Mn)
Manganese is essential for chlorophyll production. A manganese deficiency is often confused for an iron deficiency, as it too shows as yellowing leaves with green veins. Further, too much manganese may reduce iron uptake and produce symptoms similar to too little manganese!

Boron (B)
Boron is needed during reproductive growth, and helps with pollination and fruit development. It is essential for the movement of sugars into the growing parts of plants, again important in fruit development as well as more general plant growth.

Zinc (Zn)
Zinc is needed for protein production, thus affecting how tall plants can grow and mature. A zinc deficiency results in reduced fruit production.

Copper (Cu)
Copper is also important in protein production, as well as photosynthesis. It affects the flavour, sugar content, and storage life of fruit.

Molybdenum (Mo)
Molybdenum is essential to plant growth as plants require it to utilise nitrates for the production of amino acids and ultimately proteins.

As mentioned in the title, this is but an overview on the subject of plant nutrients and their importance to growth and development, and I very much would like to expand on that topic over more posts. We’ve already touched on the roles soil pH, exchangeable cations, and anions have in making available (or not) these nutrients to plants. The next stage will be to link everything together in real-time as our trees grow over the next year.