Techniques for Planting and Fertilizing Durian Trees During Their Growth Stages

1. Durian harvest seasons throughout the year

1.1. Durian season

This is the easiest flowering period to manage because it follows the natural physiological cycle of the durian tree. From December of the previous year to April of the following year, these are the dry months when the tree’s growth slows down, tending to shift to a more vigorous reproductive (flowering) phase.

The durian season is divided into three phases: early season, main season, and late season.

– Early season: XLRH in December and January will be harvested in April and May.

– Main season: Apply XLRH in February (during and after the Lunar New Year), harvest in June and July (during this period, strong weather and cashew flowering do not require XLRH).

– Late season: XLRH in March, April, harvested in July, August.

Note: To ensure high and consistent cotton yields, farmers should still use XLRH but at a lower dosage.

1.2. Durian out of season

This is a difficult flowering stage because it goes against the natural physiological cycle of the durian tree.

The XLRH (Xylia grandiflora) crop is harvested annually from May to November, during the period from September of the previous year to February of the following year. Because this is the rainy season, we must create artificial drought conditions for XLRH by covering the planting beds with rubber sheeting and then spraying with flowering stimulants.

The types of preparations used for off-season plant growth control include: MKP to support flower bud formation, and Pacloputrazol, which acts as a plant growth inhibitor to transition the plant from the growth stage to the reproductive stage. Farmers need to carefully consider the risks before applying off-season plant growth control; mild cases may weaken the plant, while severe cases can kill it.

2. Nutrition for Durian trees during the economic growth stage (8-10 years old)

2.1. Nutrition before flower induction treatment

Use durian tree fertilizer when the new shoots are in the silk leaf stage (new leaves that have just turned dark green, neither too old nor too young) to support flower bud formation. Flower induction treatment should only be carried out 10-15 days after fertilization.

– METHOD 1: Apply 3-5 kg of Super Phosphate per tree (8-10-year-old durian trees).

– METHOD 2: Apply NPK high in phosphate and potash, or if using straight fertilizers: DAP + Potash at a 1:1 ratio, 1-2 kg per tree depending on tree size.

2.2. Nutrition for flowers, small fruit and large fruit

Flower development stage counted from when the flower buds emerge at 0.5-1 cm ("crab-eye" buds), from flowering to opening (stigma emergence), lasting about one month

– Apply NPK 30-10-10 fertilizer + DAP + Calcium Nitrate Boron.

– Mix in a ratio of 3:3:1. Apply 1-2 kg per plant.

– The first fertilization should be done when the flower buds are 0.5-1cm long, and the second fertilization should be 15 days after the first.

– Note: The amount of fertilizer depends on the plant’s vitality; increase or decrease the amount to just enough to nourish the flowers. Over-fertilizing will cause the plant to produce new shoots, leading to flower drop.

– Calcium Nitrate Boron provides calcium and boron, increasing pollination and reducing flower and young fruit drop.

The fruit development stage lasts from the time the fruit starts to develop (when the fruit has a diameter of 1cm) until it weighs 1-1.5kg.

– Use NPK 30-10-10 + Calcium Nitrate Boron

– Mix at a 3:1 ratio and apply 1-2 kg per tree.

– Apply once every 7-10 days.

Note: At this stage the fruit grows very fast, so high nitrogen is needed. To reduce fruit side rot and fruit drop, add Calcium Nitrate Boron (to supply calcium and boron). Do not over-fertilize at this stage, or the tree will put out new shoots that compete with the young fruit for nutrients (causing fruit drop).

– This stage lasts 40-45 days, so there are 4-5 applications.

– Norwegian organic fertilizer Gronn 75% OM. Rate: 3-5 kg per tree. It helps supply nutrients, hold mineral nutrients against leaching, loosen the soil and strengthen the root system.

Note: Apply fertilizer once (in the Mekong Delta durian is grown off-season, so this stage falls in the middle of the rainy season).

Large fruit development stage counted from when the fruit weighs 1.5 kg until harvest.

– NPK + Calcium Nitrate Boron Mix ratio: 4:1. Apply 1.5-2 kg/plant.

– Fertilize every 7-10 days.

Note: Mainly use high-potash products with white potash (potassium sulfate, K2SO4)

For example: NPK 5-15-20, 7-15-20, 7-19-25, 9-19-19, 5-20-25

Stop fertilizing 15 days before harvest.

Note: During this stage, pay attention to the following pests and diseases: fruit rot, re-oozing, stem oozing, fruit borers, and mealybugs.

The cycle from flowering to harvest is approximately 4-4.5 months, and from flower blooming (pollination) to harvest takes 100-115 days.

Farmers should refer to the information provided before planting durian trees to ensure the best results.

Get ready for PART III OF THE TECHNIQUES FOR PLANTING AND FERTILIZING DURAN TREES: Durian Tree Care Techniques During the Recovery Phase Using Viet Nga Fertilizer!

(Refer to the overview and guide on base fertilization for durian trees HERE)