Fertilising guide
How to fertilise Longan (Dimocarpus longan)— schedule & NPK
Also called Longan, Dragon eye fruit, Lungan.
More about longan
About Longan
Dimocarpus longan · also called Longan, Dragon eye fruit · tropical
Longan, a close relative of lychee, is a subtropical evergreen tree bearing clusters of brown-skinned 'dragon eye' fruit with sweet, juicy flesh. It needs full sun, well-drained acidic soil, and a cool dry winter to flower well. Slightly more cold- and drought-tolerant than lychee but still strictly frost-sensitive.
Growth habit: Large, spreading evergreen tree with a broad rounded canopy and glossy compound leaves; moderately vigorous.
Watch for — Alternate (biennial) bearing: Longan often crops heavily one year then lightly the next; thinning fruit and steady feeding help even out yields.
What fertiliser longan actually wants — and why
Longan is an acid-loving plant — it can only take up nutrients in acidic soil, so the feed itself matters less than using an ericaceous formula and never liming.
An ericaceous (acidic) fertiliser, formulated to keep the soil pH low and supply iron and trace elements in a form acid-loving roots can absorb. Ordinary feeds and any lime lock out iron and yellow the leaves.
For the language behind the three numbers on the bottle — what nitrogen, phosphorus and potassium each do — see the NPK ratio explained entry. The short version for longan: match the feed to the job the plant is doing right now, not to a generic “plant food” on the shelf.
How often to feed longan, and which months
Feeding only earns its keep while the plant is in active growth and can use the nutrients — pour feed into a dormant or low-light plant and it simply builds up as root-burning salt. For longan:
Feed regularly in the growing season with a balanced fertiliser, reducing nitrogen ahead of flowering. Apply micronutrients and chelated iron where soils trend alkaline to prevent chlorosis. In practice: an ericaceous feed in spring as growth resumes, repeated through the main growing months; never apply lime, bonemeal or wood ash, which raise pH.
The dormant-season rule matters more than the exact interval: skip feeding entirely when longan is resting. For the wider context on indoor feeding rhythms across the seasons, the houseplant fertiliser schedule walks through the year month by month.
What strength to mix for longan
Follow the ericaceous product's own rate — these are formulated for the plant, so the dilution on the label is right for longan. The variable that actually matters is pH, not concentration.
Feeding always goes onto already-damp soil, never dry roots — water longan first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the longan watering schedule.
Signs you are over-feeding longan
Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for longan:
- Brown, scorched leaf margins from too strong or too frequent a dose.
- White salt crust on the soil surface.
- Soft, lush growth that fruits or flowers poorly.
Signs you are under-feeding longan
- Yellowing leaves with green veins (iron chlorosis from high pH).
- Weak growth, poor cropping and an overall pale, stressed look.
- Stunted new shoots in spring despite adequate water and light.
If the symptoms point at watering, light or roots rather than nutrition, the full longan care brief covers soil, humidity and the common problems for this species.
Flushing and leaching the salts
Flush longan with rainwater (not hard tap water, which raises pH) if salts build up; better still, mulch with pine needles or composted bark and water with rainwater to hold the acidity.
Organic vs synthetic feeds for longan
Organic options
Composted pine bark, pine-needle mulch, used coffee grounds and an organic ericaceous feed gently maintain acidity. UK: Vitax or Westland Ericaceous; US: Espoma Holly-tone or Dr. Earth Acid Lovers. Slow, soil-improving, hard to overdo.
Synthetic / liquid feeds
A liquid or granular ericaceous feed — UK: Miracle-Gro Ericaceous, Vitax or Westland; US: Miracle-Gro Acid-Loving Plant Food or Espoma Holly-tone. Pair with rainwater and an acidic mulch for it to work.
Brand names are examples, not endorsements, and UK and US ranges differ — check the label’s own NPK and dilution rate, since formulations change.
Fertilising longan — frequently asked questions
What fertiliser does longan need?
An ericaceous (acidic) fertiliser, formulated to keep the soil pH low and supply iron and trace elements in a form acid-loving roots can absorb. Ordinary feeds and any lime lock out iron and yellow the leaves. Longan is an acid-loving plant — it can only take up nutrients in acidic soil, so the feed itself matters less than using an ericaceous formula and never liming.
How often should I feed longan?
Feed regularly in the growing season with a balanced fertiliser, reducing nitrogen ahead of flowering. Apply micronutrients and chelated iron where soils trend alkaline to prevent chlorosis. Feed regularly in the growing season with a balanced fertiliser, reducing nitrogen ahead of flowering. Apply micronutrients and chelated iron where soils trend alkaline to prevent chlorosis. In practice: an ericaceous feed in spring as growth resumes, repeated through the main growing months; never apply lime, bonemeal or wood ash, which raise pH.
What strength of feed for longan?
Follow the ericaceous product's own rate — these are formulated for the plant, so the dilution on the label is right for longan. The variable that actually matters is pH, not concentration.
What does over-feeding longan look like?
Brown, scorched leaf margins from too strong or too frequent a dose. White salt crust on the soil surface. Soft, lush growth that fruits or flowers poorly. Feeding longan an ordinary fertiliser, or growing it in hard tap water / limey soil, is the defining mistake — it triggers lime-induced chlorosis (yellow leaves, green veins) no amount of feeding fixes until the pH comes down.
Should I flush the soil of longan?
Flush longan with rainwater (not hard tap water, which raises pH) if salts build up; better still, mulch with pine needles or composted bark and water with rainwater to hold the acidity.
Keep reading
- Longan care — the full brief (light, soil, humidity, problems, pet safety)
- How often to water longan — the watering schedule
- The houseplant fertiliser schedule — feeding through the year
- NPK ratio explained — what the three numbers on the bottle mean
- How to fertilise monstera
- How to fertilise pothos
- How to fertilise fiddle leaf fig
- All 5561 fertilising guides in the Growli library