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Plant care

Korlan care

Nephelium hypoleucum

Also called Korlan, Korlan Tree.

RHS H1aUSDA 10b–11Mildly toxic to petsIndoor 12–25 m tall in the wild

Watering rhythm

4-6days

Every 4–6 days for young trees; reduce to every 10–14 days once established in seasonally wet climates

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Light

Direct sun (at least 4-6 hours)

Soil

Fertile, well-draining sandy loam to loam

Humidity

70–90%

Temp

20–35°C

Pet safety

Mildly toxic to pets

Mature size

12–25 m tall in the wild

Care at a glance

Light

Aim for at least 4-6 hours of direct sun on the leaves. Thrives in full tropical sun. Native plants grow in the upper forest canopy or forest margins where they receive strong, direct light for most of the day. In cultivation, a minimum of 6 hours of unobstructed direct sun is needed for good growth and fruit development. If your only bright window faces south, that's perfect for korlan — same window any aroid would fry on.

Watering

Watering korlan: every 4–6 days for young trees; reduce to every 10–14 days once established in seasonally wet climates. The number that matters isn't the day of the week — it's how dry the top 2-3 cm of the pot feels. A finger in the soil tells you more than a watering app. After every watering, tip the saucer. Requires consistent moisture, reflecting its native habitat in high-rainfall tropical highlands. Deep watering encourages deep root growth. Allow the top few centimetres to dry between waterings; standing water around the base causes root decline. A seasonal dry period may encourage flowering in mature trees.

Soil and pot

Korlan grows best in fertile, well-draining sandy loam to loam. Naturally found in fertile forest soils rich in organic matter. Performs best in sandy loam with excellent drainage; tolerates slightly higher altitude conditions up to 1,200 m where soils tend to be loamy and humus-rich. pH should be slightly acidic, 5.5–6.5. Avoid heavy, poorly drained soils. A pot with a working drainage hole is non-negotiable for this species — even free-draining mix will turn soggy in a closed planter. If you love the look of a decorative pot without a hole, use it as a cachepot around an inner nursery pot you can lift out to water.

Humidity and temperature

Korlan sits happiest at around 70–90% humidity and 20–35°C (68–95°F). Adapted to the warm, high-humidity conditions of Southeast Asian tropical forests. Requires persistently high ambient humidity; does not tolerate dry climates. In cultivation outside its native range, supplemental misting and mulching help replicate the humid conditions it needs. If you keep the room above 20–35°C year-round and avoid placing the plant near a cold draught, a hot radiator, or an air-conditioning vent, you have already handled the two biggest indoor stressors.

Fertilising

Feed korlan sparingly. Apply a balanced tropical fruit tree fertilizer (NPK 10-10-10) three times per year during the active growing season. Incorporate compost into the soil annually. Avoid excessive nitrogen, which promotes vegetative growth at the expense of fruiting. Skip fertiliser entirely on a stressed, recently-repotted, or actively wilting plant — fertiliser salts make damage worse, not better. Wait for a round of healthy new growth before resuming a feeding rhythm.

Common problems

Below are the issues we see most often on korlan in the Growli community. Each is annotated with the most common cause so you know where to start.

  • Poor fruit set in cultivation — Korlan is rarely cultivated away from its native range and may fail to flower without the correct seasonal cues (slightly cooler, drier period). Grafted material is extremely scarce; most plants from seed take many years to reach reproductive maturity.
  • Root rot in low-drainage soils — Native to well-draining forest soils; compacted or waterlogged soils in cultivation cause rapid root decline. Always plant in raised beds or well-amended free-draining soil.
  • Scale insects and aphids — Young succulent growth is vulnerable to scale insects and aphids, especially under stress. Monitor new flushes and treat early with neem oil or horticultural soap spray to prevent colony establishment.

Propagation

Propagated from fresh seed, which should be sown immediately after harvest as viability is short-lived (weeks). Air layering has been reported as a viable alternative for preserving selected traits. Grafting onto Nephelium lappaceum (rambutan) rootstock is possible but rarely practiced due to the species' rarity in cultivation. Propagation is the cheapest, most satisfying way to expand a collection — and it doubles as insurance against losing a mature plant to an accident. Take a backup cutting once the parent is established and healthy.

Toxicity to pets

Korlan is mildly toxic to pets. Nephelium hypoleucum is not individually listed by ASPCA. As a Sapindaceae member closely related to rambutan and lychee, the seeds are suspected to contain cyanogenic compounds and pose a hazard if ingested by pets. The aril pulp is not reported as toxic in humans, but pets should not access seeds. Contact a vet if seed ingestion is suspected. If you keep cats, dogs, or curious children in the house, weigh placement carefully — a high shelf or a hanging planter is enough for casual safety. For severe ingestion incidents, call your local vet and the ASPCA Animal Poison Control Center (in the US, 888-426-4435).

Pet-safety status is sourced from the ASPCA Toxic and Non-Toxic Plant List, which catalogues the most-asked-about plants for cats, dogs, and horses.

Korlan care — frequently asked questions

What is Korlan?

Korlan (Nephelium hypoleucum) is a tropical houseplant with a medium to large evergreen tree; pinnately compound leaves with pale undersides (hypoleucum = white beneath) growth habit, reaching 12–25 m tall in the wild; likely maintained at 6–10 m in managed cultivation at maturity. Korlan is a rare, semi-wild fruit tree from the Sapindaceae family, native to the rainforests of Thailand, Laos, Cambodia, and Vietnam. Closely related to rambutan, its yellowish fruits have a less spiny pericarp and a translucent, sweet aril that is notably sweeter than rambutan.

How much light does korlan need?

Korlan grows best in direct sun (at least 4-6 hours). Thrives in full tropical sun. Native plants grow in the upper forest canopy or forest margins where they receive strong, direct light for most of the day. In cultivation, a minimum of 6 hours of unobstructed direct sun is needed for good growth and fruit development.

How often should I water korlan?

Water korlan every 4–6 days for young trees; reduce to every 10–14 days once established in seasonally wet climates. Requires consistent moisture, reflecting its native habitat in high-rainfall tropical highlands. Deep watering encourages deep root growth. Allow the top few centimetres to dry between waterings; standing water around the base causes root decline. A seasonal dry period may encourage flowering in mature trees. The finger-test (or lifting the pot to feel its weight) beats a fixed weekly calendar because pot size, light, and season all change how fast the soil dries.

Is korlan toxic to cats and dogs?

Korlan is mildly toxic to pets. Nephelium hypoleucum is not individually listed by ASPCA. As a Sapindaceae member closely related to rambutan and lychee, the seeds are suspected to contain cyanogenic compounds and pose a hazard if ingested by pets. The aril pulp is not reported as toxic in humans, but pets should not access seeds. Contact a vet if seed ingestion is suspected.

What USDA hardiness zone does korlan grow in?

Korlan is rated for USDA zone 10b–11 and RHS hardiness H1a. Outside that range, grow it as a container plant that overwinters indoors before the first hard frost.

Korlan deep-dive guides

Every aspect of korlan care, each with its own calibrated guide:

Featured in these plant shortlists

Korlan qualifies for 3 curated Growli shortlists — each one filtered objectively from our structured plant-care library, so the selection is consistent and checkable:

Related guides

Korlan is also commonly called Korlan or Korlan Tree.