Fertilising guide
How to fertilise Black Fang Begonia (Begonia 'Black Fang')— schedule & NPK
Also called Black Fang begonia, Black Fang eyelash begonia.
More about black fang begonia
About Black Fang Begonia
Begonia 'Black Fang' · also called Black Fang begonia, Black Fang eyelash begonia · houseplant
Begonia 'Black Fang' is a striking eyelash begonia (Begonia bowerae hybrid) distinguished by its very dark, near-black, deeply lobed leaves edged with fine white eyelash hairs and accented by bright green markings along the veins, giving it a dramatic gothic appearance. It is compact and relatively easy to grow in moderate indoor conditions, producing dainty pale pink flowers in late winter that contrast beautifully with the near-black foliage. As with all rhizomatous begonias, the paramount care rule is to avoid overwatering, since the shallow rhizome is extremely sensitive to soggy compost. Toxic to cats and dogs per the ASPCA.
Growth habit: Low-growing, spreading rhizomatous begonia with a creeping rhizome producing a mound of angular, deeply lobed, near-black leaves with contrasting vein patterns.
What fertiliser black fang begonia actually wants — and why
Black Fang Begonia 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 black fang begonia: 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 black fang begonia, 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 black fang begonia:
Apply a balanced liquid fertiliser at one-quarter to one-half strength once a month from spring through early autumn; withhold feeding completely in winter when the plant enters a rest period. Treat that as once a month 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 black fang begonia 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 black fang begonia
Half strength is the safe default for black fang begonia — 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 black fang begonia first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the black fang begonia watering schedule.
Signs you are over-feeding black fang begonia
Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for black fang begonia:
- 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 black fang begonia
- 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 black fang begonia care brief covers soil, humidity and the common problems for this species.
Flushing and leaching the salts
Flush the pot of black fang begonia 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 black fang begonia
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 black fang begonia — frequently asked questions
What fertiliser does black fang begonia 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. Black Fang Begonia 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 black fang begonia?
Apply a balanced liquid fertiliser at one-quarter to one-half strength once a month from spring through early autumn; withhold feeding completely in winter when the plant enters a rest period. Apply a balanced liquid fertiliser at one-quarter to one-half strength once a month from spring through early autumn; withhold feeding completely in winter when the plant enters a rest period. Treat that as once a month 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 black fang begonia?
Half strength is the safe default for black fang begonia — houseplant feeds are formulated strong, and the diluted dose is gentler on the roots while still ample for foliage.
What does over-feeding black fang begonia 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 black fang begonia 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 black fang begonia?
Flush the pot of black fang begonia 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
- Black Fang Begonia care — the full brief (light, soil, humidity, problems, pet safety)
- How often to water black fang begonia — 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 nardoo
- How to fertilise american climbing fern
- How to fertilise ring fern
- All 10153 fertilising guides in the Growli library