I am an agronomist at the Western Highlands Agriculture and Forestry Science Institute (WASI, formerly the Coffee Research Institute) and have spent over 25 years studying coffee cultivation. After reading Dr. Lê Xuân Đính’s article “Pruning Techniques for Coffee Trees” (Vietnam Agriculture Newspaper No.120, June 17, 2009), I would like to share several points of clarification:
1. On the terms “light pruning” and “hard pruning”
For coffee, the expressions “đốn phớt” (light pruning) and “đốn đau” (hard pruning) simply do not exist in any global or Vietnamese coffee-cultivation literature.
Based on coffee’s physiology—especially Robusta—researchers have long focused on canopy training: maintaining a balanced crown and an even distribution of fruit-bearing branches to ensure high, stable yields and to extend the plant’s productive life.
Worldwide, there are two recognized systems:
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Single-stem training, which exploits fruit from secondary branches.
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Multi-stem training, which relies on the primary branches of several stems.
WASI’s research recommends single-stem training with tip-pinching for Robusta in the Central Highlands. This maximizes yield from secondary branches and is combined with twice-yearly branch pruning:
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once after harvest,
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once mid-rainy season.
This maintains a healthy framework of secondary branches for the next crop. New secondary branches formed within the same year rarely produce many flower buds, so annual “light pruning” that continually raises the fruiting zone higher and higher is scientifically unsound.
Over years of production, as the lower primary branches gradually die off, WASI advises stumping for rejuvenation to enter a second production cycle. When trees become too old—poor growth, weak root systems, low yields—farmers should uproot and replant.
All of WASI’s findings on coffee canopy management were officially recognized as a technical advance in 1995 and have been regularly updated. The method has helped raise Robusta yields by roughly 250–300% compared with the past and has extended the economic life of coffee plantations.
Therefore, applying so-called “light pruning” every year is inappropriate: it mainly produces leaves rather than berries. Likewise, the suggestion to perform “hard pruning” where many main branches remain is impractical. After years of cultivation the lower main branches of Robusta naturally die back; only branches at about 1.0–1.4 m above ground remain, so “hard pruning” is essentially impossible.
Such pruning terms belong to crops harvested for leaves or young shoots (for example, tea). Tea scientists developed those practices based on the tea plant’s own physiology and shoot-growth habits, which simply do not apply to coffee.
2. On “rejuvenating” coffee roots
The article also asks whether and how coffee roots should be “rejuvenated.” This is a question that, until now, no one had formally posed. From 1995 to 2000 WASI already researched and recommended practical root-system improvement techniques, recognized as an official technical advance:
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Green manuring (ép xanh) to refresh feeder roots while adding organic matter.
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Inter-row ploughing to stimulate new feeder-root growth.
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Mandatory root renovation when stumping trees for a second production cycle.
Robusta’s feeder roots that absorb water and nutrients are concentrated in the top 0–30 cm of soil. As trees age these roots senesce and their uptake ability declines, so some root improvement is necessary.
However, the notion of annual “root rejuvenation” as described in the article is vague and scientifically unfounded, for six reasons:
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Location: root improvement should target the inter-row or under the canopy—wherever the canopy spreads, the feeder roots extend—so no special “spot” needs to be found.
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Depth: only the top 0–30 cm of soil needs treatment.
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Frequency: carry out root renovation only every 2–3 years. Annual “root pruning” would weaken growth because roots would not recover.
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Extent: treat only about 50 % of the feeder-root zone at a time, in rotation. Cutting all feeder roots at once prevents the tree from taking up enough water and nutrients.
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Method: it cannot be done by “light” or “hard” cutting as suggested; such severe wounding would invite soil-borne diseases and stunt or kill the trees.
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Timing: cutting roots right after harvest is incorrect. At that time trees are physiologically weakened and entering the dry season. Cutting roots then—when buds are differentiating in preparation for flowering—would cause physiological shock, hinder flowering and fruit set, and could even kill the tree despite fertilizer application.
In short, proper coffee management relies on scientifically tested canopy-training and root-maintenance techniques, not on the so-called “light” or “hard” pruning methods, and any root renovation must be carefully timed and limited to protect yield and plant health.