Fertilising guide
How to fertilise Naranjilla (Solanum quitoense)— schedule & NPK
Also called Naranjilla, Lulo, Little orange.
More about naranjilla
About Naranjilla
Solanum quitoense · also called Naranjilla, Lulo · tropical
Naranjilla is a striking Andean nightshade shrub with huge purple-veined felted leaves and round orange fruit yielding tangy green pulp used in juices. It favours cool, humid highland conditions, dappled light and protection from intense heat and frost. Spiny forms exist; as a nightshade its leaves and unripe fruit contain solanine and are not edible.
Growth habit: A short-lived, fast-growing soft-wooded shrub with thick stems and very large, ovate, purple-tinged leaves covered in fine felted hairs; some forms bear spines. Clusters of white-and-purple flowers precede the felted orange fruit, which is rubbed clean before use.
What fertiliser naranjilla actually wants — and why
Naranjilla is an easy, light foliage feeder — a half-strength balanced liquid feed through the growing months keeps it green without forcing weak, sappy growth.
A balanced general houseplant feed (roughly even N-P-K) is exactly right — it is grown for foliage, so steady, moderate nitrogen for healthy leaves is the goal, not a bloom or root formula.
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 naranjilla: 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 naranjilla, 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 naranjilla:
A hungry, fast-growing plant that benefits from regular feeding through the growing season with a balanced fertiliser, shifting to higher potassium as it flowers and fruits. Rich soil and steady feeding support the large leaves and continuous cropping. Reduce feeding in cool, low-light periods. Treat that as sparingly through the growing season between spring through early autumn (roughly March to September); ease off in autumn and stop entirely in the low light of winter.
The dormant-season rule matters more than the exact interval: skip feeding entirely when naranjilla 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 naranjilla
Half strength is the safe default for naranjilla — houseplant feeds are formulated strong, and the diluted dose is gentler on the roots while still ample for foliage.
Feeding always goes onto already-damp soil, never dry roots — water naranjilla first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the naranjilla watering schedule.
Signs you are over-feeding naranjilla
Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for naranjilla:
- Brown, crispy leaf tips and edges with no sign of underwatering.
- A white, crusty salt deposit on the soil surface or pot rim.
- Weak, pale, stretched new growth that flops.
- Lower leaves yellow and drop while the soil is correctly watered.
Signs you are under-feeding naranjilla
- Uniformly pale or yellow-green leaves, oldest first.
- Noticeably small new leaves and stalled growth in good light and season.
- A generally tired, lacklustre look despite correct watering and light.
If the symptoms point at watering, light or roots rather than nutrition, the full naranjilla care brief covers soil, humidity and the common problems for this species.
Flushing and leaching the salts
Flush the pot of naranjilla with plain water until it runs freely from the base every couple of months in the feeding season — it washes out the fertiliser salts that cause brown tips.
Organic vs synthetic feeds for naranjilla
Organic options
A diluted seaweed or worm-casting feed, or fish emulsion if you can tolerate the smell indoors. UK: Westland or Baby Bio Organic, dilute seaweed; US: Espoma Indoor! or Neptune's Harvest fish & seaweed. Slow, gentle and hard to overdo.
Synthetic / liquid feeds
A general-purpose houseplant liquid at half strength — UK: Baby Bio, Westland Houseplant Feed or Phostrogen; US: Miracle-Gro Indoor Plant Food or Schultz. Convenient and fast-acting; the only risk is overdoing it.
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 naranjilla — frequently asked questions
What fertiliser does naranjilla need?
A balanced general houseplant feed (roughly even N-P-K) is exactly right — it is grown for foliage, so steady, moderate nitrogen for healthy leaves is the goal, not a bloom or root formula. Naranjilla is an easy, light foliage feeder — a half-strength balanced liquid feed through the growing months keeps it green without forcing weak, sappy growth.
How often should I feed naranjilla?
A hungry, fast-growing plant that benefits from regular feeding through the growing season with a balanced fertiliser, shifting to higher potassium as it flowers and fruits. Rich soil and steady feeding support the large leaves and continuous cropping. Reduce feeding in cool, low-light periods. A hungry, fast-growing plant that benefits from regular feeding through the growing season with a balanced fertiliser, shifting to higher potassium as it flowers and fruits. Rich soil and steady feeding support the large leaves and continuous cropping. Reduce feeding in cool, low-light periods. Treat that as sparingly through the growing season between spring through early autumn (roughly March to September); ease off in autumn and stop entirely in the low light of winter.
What strength of feed for naranjilla?
Half strength is the safe default for naranjilla — houseplant feeds are formulated strong, and the diluted dose is gentler on the roots while still ample for foliage.
What does over-feeding naranjilla look like?
Brown, crispy leaf tips and edges with no sign of underwatering. A white, crusty salt deposit on the soil surface or pot rim. Weak, pale, stretched new growth that flops. Lower leaves yellow and drop while the soil is correctly watered. Feeding naranjilla year-round on a fixed schedule, including dark winter months, is the most common mistake — it cannot use the nutrients in low light and the surplus simply burns the roots and crusts the soil.
Should I flush the soil of naranjilla?
Flush the pot of naranjilla with plain water until it runs freely from the base every couple of months in the feeding season — it washes out the fertiliser salts that cause brown tips.
Keep reading
- Naranjilla care — the full brief (light, soil, humidity, problems, pet safety)
- How often to water naranjilla — 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