Instructions for productive jackfruit care

Thai jackfruit + red-fleshed jackfruit need different care in each stage. Instructions on irrigation, fertilization, pruning, fruit pruning and handling 3 common productivity problems — for jackfruit orchards in the Mekong Delta and Southeast.

Summary: Jackfruit is an easy plant to grow but difficult to produce stable yields. Many Thai jackfruit orchards waste their potential because of improper care — especially skipping the step of pruning the fruit + fertilizing the fruit. This article guides the care schedule according to 4 tree stages + 3 common productivity problems.

Applies to: Thai Changai jackfruit, To Nu jackfruit, Red-fleshed jackfruit in the Mekong Delta, Southeast, and low Central Highlands.
Duration: Continuous care, stable productivity from year 3 onwards.
Difficulty level: Medium. Jackfruit trees are easy-going but need discipline to care for.
Estimated additional costs: 8-15 million/ha/year fertilizer + treatment + labor.

Biological characteristics of jackfruit

Jackfruit has 3 characteristics that need to be understood before cultivating:

Shallow root system (mainly in the top 50cm of soil) → does not tolerate waterlogging + needs to be watered evenly in dry season.
The tree flowers + bears fruit all year round in hot areas (Mekong Delta). You can have 2-3 crops/year if you take good care of it. Unlike durian, there is only one main crop.
The fruit can weigh 5-15kg Thai jackfruit, 2-5kg of To Nu jackfruit → fruit-bearing branches must be strong and properly pruned.

The 3-year-old jackfruit tree has given fruit. 5-7 year old trees are in stable business. Economic life cycle 20-30 years.

Care schedule according to tree stages

Basic construction (years 1-3)

Goal: create a basic canopy + strong roots. Do not let jackfruit produce young fruit in year 1-2 — cut off flowers if they appear early.

Irrigation: 30-50 liters/tree/time, 2-3 days/time in dry season. The rainy season is self-sufficient.

Fertilization:

Fertilize the roots 4 times/year. NPK 16-16-8: 200-300g/tree/time.
Organic compost 5-8 kg/tree/year divided into 2 times.
Fused phosphorus 200-300g/plant in the first year (long lasting).

Pruning branches to create canopy:

Leave 1 main stem + 4-5 level 1 branches.
Remove excess shoots and branches that grow over them.
Create a canopy shaped like a Buddhist tree for easy harvesting + even lighting.

Early stage business (years 3-5)

The tree has begun to bear fruit but has not yet reached its peak. Principle:

Year 3: keep 5-10 fruits/tree/crop.
Year 4: keep 15-25 fruits/tree/crop.
Year 5: keep 25-40 fruits/tree/crop.

Hold on to early fruit = exhausted tree, short economic life cycle.

Stable business (years 5-15)

Peak productivity. A healthy Thai jackfruit tree can produce 50-100 fruits/tree/year (divided into 2-3 crops).

Fertilization (mature tree):

4-6 times/year NPK 16-16-8 or 15-15-15. Dosage 500-800g/tree/time.
Organic 15-25 kg/tree/year.
Potassium sulfate 200-400g/plant before harvest — increases rice quality.

Late life + old tree (year 15+)

Productivity gradually decreases. Consider:

Improve the canopy by grafting lower branches.
Or gradually replant (same coffee replanting process).

Care process during flowering + fruit growing season

Before flowering (plant preparation)

When the buds are old + flower buds appear:

Fertilize with NPK 6-30-30 + TE, 300-500g/plant.
Water evenly every 5-7 days.
Prune dry branches + branches in the canopy for ventilation.

Flowering + pollination

Jackfruit has male flowers + female flowers on the same tree. Natural pollination through ants + insects:

Do not spray during flowering period.
Additional pollination can be done by hand: take male pollen and rub it on female flowers at 7-9am. Increase passing rate by 20-30%.

Young fruit set — Fruit pruning determines quality

When the young fruit is the size of a chicken egg:

Count the number of fruits on each branch. Rules: 1 fruit/level 2 branch with Thai jackfruit. 2-3 fruits with To Nu jackfruit (smaller fruit).
Discard: deformed fruit, small fruit in bunches, fruit growing in the same position, fruit close to the ground.
Keep: beautiful fruit, grows straight, strong stem, no borers.

Thai jackfruit greedy for fruit = small fruit, uneven rice, low selling price. Pruning vigorously is discipline.

Fruit farming + harvesting

Fertilization (30-45 days after fruit set):

NPK 12-12-17 + TE: 500-700g/tree.
Spray leaves KNO3 + Calcium-Boron 1-2 times.

Fruit bags (for trees exported or sold at high prices):

Cover with a perforated PE bag to drain moisture when the fruit weighs 1-2kg.
Helps avoid fruit borers + yellow flies.

Harvest: usually 4-5 months later fruit sets with Thai jackfruit. Observation:

The peel turns pale yellow.
Has a light fragrance.
Clap your hands to hear the bass.
The stem begins to wilt.

Three common productivity problems

Little flowering / no flowering

Cause:

Too much nitrogen fertilizer → plants push out buds instead of flowering.
Watering too evenly all year round → the plant does not receive dry signals.
The plant is too dense → flower buds do not develop.

How to fix:

Cut back nitrogen 6 weeks before you want the plant to flower.
Stop watering for 10-15 days for mild stress.
Pruning branches to open the canopy.
Apply NPK 6-30-30 times to stimulate flowering.

Young fruit falling

Cause:

Water stress (alternating dry-wetting).
High nitrogen fertilization during the fruit-setting stage → plants push buds.
Irregular pollination → fruit develops distortedly and falls off.
Left stem borer.

How to fix:

Keeps moisture stable.
Reduce protein 30 days after fruit set.
Spray 1% KNO3 if the tree is in the middle of growing fruit.
Spray Emamectin benzoate if borers are detected.

The fruit has black fibers (black center)

Black fiber disease in jackfruit = the middle area of the fruit is dark, inedible. Cause:

Lack of calcium + boron during fruit growing stage.
Uneven watering, especially lack of water in the final stages.
Susceptible variety (popular Thai Changai jackfruit).

How to fix:

Spray the leaves with Calcium-Boron 2-3 times during the fruit growing stage.
Water evenly, do not let it dry suddenly.
Choose resistant varieties if planting new trees.

Follow up every 2 weeks

[ ] Condition of buds + new leaves.
[ ] Have flowers / flower buds appeared yet?
[ ] Number of fruit + condition of immature fruit.
[ ] Stalk borers + stem borers.
[ ] Soil moisture + irrigation status.

Common mistakes

Too much nitrogen fertilization all year round: the tree is lush but does not flower, or continuously drops young fruit.

Hold fruit: 70-100 fruits/young tree = exhausted tree, next crop "sleeps".

Do not cover the fruit in the orchard there are yellow flies + borers: the fruit is damaged before it is ripe.

Spray when flowers bloom: kill ants + bees → fruit setting rate reduced by 30-50%.

Stop pruning because of "regret": canopy is too thick, yield + quality gradually decreases.

Take notes

Blooming date + fruiting date + harvest date.
Number of fruits kept / tree.
Average weight + total yield.
Materials for fertilization + spraying during the season.
Ratio of black fibrous fruit / fruit with worms.

References

*Technical process of planting and caring for jackfruit* — Southern Fruit Institute, 2022.
*Production of jackfruit for export* — Department of Crop Production, 2023.