Watering techniques for coffee plants in each stage

Watering coffee is not just about having enough water. Each growth stage requires a different amount of water and irrigation method. Instructions in four stages — post-harvest, flower stimulation, fruit raising, ripening — suitable for Robusta orchards in the Central Highlands.

Summary: Watering the right amount at the right time is more important than watering too much. Irrigation at the wrong stage — such as watering heavily when the plant has just finished harvesting but has not yet rested — can cause the plant to flower prematurely and uncontrollably, losing 30-50 percent of the next crop's yield. This article separates the irrigation schedule into four stages of Robusta growing in the Central Highlands, each stage has different principles.

Applies to: Robusta Coffee in Dak Lak, Gia Lai, Lam Dong, Dak Nong, Kon Tum. Business tree from 4 years old or older.
Duration: The entire year's life cycle, focusing on four important milestones.
Difficulty level: Medium. Need to read signs of plant physiology.
Estimated additional costs: 8-15 million VND per hectare for pumping fuel and irrigation system maintenance.

Why does each stage need different amounts of water

Coffee trees have a typical annual cycle in the Central Highlands:

October-November: harvest. The tree is exhausted and needs rest.
December-January: recovery and differentiation of flower buds.
February-March: flowering, young fruit set.
April-September: fruit growth and seed development.
October: ripe and ready to fall.

Each stage of plants has very different water needs. Flower bud differentiation needs to be moderately dry — the plant must receive the signal "it's time to flower". Growing fruit requires even moisture — the fruit's final size depends on stable water in the last three months.

Irrigation the same amount all year round is a common mistake.

Phase 1 — Post-harvest (November-December)

Principles

After harvest, the coffee tree has used up all its starch reserves to feed the fruit. Leaves can lose 30-50 percent. This is a period of recovery, not stimulation.

Amount of water

Stop watering completely 25-35 days after harvesting. Allow the plant to "moderately dry" to stop nutritional growth and begin to differentiate flower buds.
After the dry period, water the recovery phase: 300-400 liters per commercial tree.

Note

Don't water right after harvesting because "the plant looks weak". Plants need dry signals to enter the reproductive cycle.
If the rain at the beginning of the dry season still persists, postpone the restoration schedule for another 10-15 days.
Apply 5-8 kilograms of organic fertilizer per tree during this period to prepare the nutritional base.

Stage 2 — Flower induction and flowering (January-February)

Principles

This is the stage that determines productivity. The plant needs a heavy watering after a dry period to stimulate flowers to bloom simultaneously. Watering at the wrong time — too early or too late — will cause scattered blooms, reduced productivity and difficulty in organizing future harvests.

Amount of water

Irrigation to stimulate flowers: 450-550 liters per commercial plant. Water deeply once for 1-2 days in a row.
After the flower stimulation, monitor: flower buds become clear after 5-7 days, bloom after 10-15 days.
When flowers are blooming: dramatically reduce watering to 100-150 liters per plant per week. Watering vigorously when the flowers are in bloom causes a lot of flowers to drop.

Note

Irrigation to stimulate flowers requires enough water to penetrate 50-80 centimeters into the root layer. Watering little will only wet the ground, it will have no effect.
Look at the sky. If light rain is forecast in the next 5-7 days, irrigation can be reduced by 30 percent — the rain will supplement.
Avoid spraying water on the canopy near flowers. Wet leaves increase the risk of fungal diseases on flowers.

Stage 3 — Fruit set and fruit growing (March-August)

Principles

After the flowers bloom and bear fruit, the tree enters a 5-6 month long growing period. The principle at this time is evenly moist, not fluctuating. Each sudden dry spell causes the fruit to fall or become flat.

Amount of water

March-April (early fruit growing): 250-350 liters per tree, watered evenly every 20-25 days.
May-August (rainy season begins): mainly relies on natural rain. Add irrigation when there is a long dry period of 7-10 days.

Note

Watch the rain closely. The Central Highlands may have "fake rain" — a few light rains then stop for 10-15 days. Don't rely on general forecasts for the entire province.
Fertilize according to irrigation schedule: apply immediately after irrigation or rain, fertilizer is best absorbed.
If the orchard loses flower buds due to incorrect watering in phase 2, do not save it by fertilizing with high nitrogen. Concentrate on preserving the tree's strength for the next crop.

Stage 4 — Fruits ripen and ready to harvest (September-October)

Principles

In the final stage, the fruit is changing from green to ripe red. Watering too much at this time will cause the fruit to become pale, the beans to be light, and the quality of green coffee to decrease.

Amount of water

Reduce watering by 30-40 percent compared to the fruit growing stage.
Mainly depends on late season rainfall. Only supplement when there is a dry spell lasting 14 days or more.
2-3 weeks before harvest: stop watering completely so that the fruit concentrates starch and sugar, increasing kernel quality.

Note

Don't water heavily before harvest because "you want big, beautiful fruit". A lot of water at the end of the season makes the seeds light and easy to fall when harvested.
Ripe fruit needs enough sunlight. Wetting the canopy increases air humidity, prolonging ripening time.

How to check soil moisture for coffee

Unlike durian, which has concentrated roots 60-80 centimeters deep, coffee has main roots 80-120 centimeters deep in red basalt soil. Testing needs to dig deeper.

How to practice:

Dig 30-40 centimeters deep at the edge of the canopy.
Take the soil and squeeze it gently. The soil is clumpy but does not leak water = moderately moist.
Loose, crumbly soil = dry main root layer. Needs irrigation.

Different lands hold water differently. Dak Lak red basalt soil retains water 1.5-2 times longer than Gia Lai gray granite soil. Don't apply the same irrigation schedule to two other types of soil.

Monitor each irrigation session

[ ] Actual water volume (running hours multiplied by nozzle flow).
[ ] Moisten the soil immediately before watering.
[ ] Plant reaction after 3-5 days — leaf color, gloss, buds.
[ ] Condition of flower buds or young fruit (depending on stage).
[ ] Rainfall, if any, during the monitoring period.

Common mistakes

Water all year round in equal amounts: ignore the plant's biological cycle. Unable to stimulate flowers, or cause plants to flower prematurely and uncontrollably.

Irrigate immediately after harvest to "save weak plants": on the contrary, it prolongs the nutritional growth phase, and flower buds are poorly differentiated.

Water vigorously while flowers are blooming: 20-40 percent flower loss in 2-3 days.

Measuring soil moisture at ground level: dry top soil does not mean dry root layer. Must dig deeper to check.

Canopy sprinkler irrigation: evaporation of 30-40 percent before entering the soil, waste. Drip or root irrigation is 2-3 times more effective.

Recorded by year

For each irrigation session, record: date, plant stage, amount of water, soil moisture before watering, plant reaction after 5-7 days. At the end of the year, summarize: total amount of water per hectare, number of irrigation cycles, rate of flower or fruit loss in each stage.

Data after 2-3 years helps fine-tune the irrigation schedule for the orchard. There is no common irrigation schedule for all coffee orchards in the Central Highlands.

References

*Technical watering process for Robusta coffee* — Central Highlands Agricultural and Forestry Science and Technology Institute (abbreviated name WASI), 2018, updated 2023.
*Limited coffee watering recommendations* — Department of Crop Production, 2022.