Fertilising guide
How to fertilise Begonia 'Black Velvet' (Begonia rex-cultorum 'Black Velvet')— schedule & NPK
Also called black velvet rex begonia, dark rex begonia.
More about begonia 'black velvet'
About Begonia 'Black Velvet'
Begonia rex-cultorum 'Black Velvet' · also called black velvet rex begonia, dark rex begonia · houseplant
Begonia 'Black Velvet' is a rex-cultorum hybrid grown for its near-black, velvety, deeply textured leaves with a subtle metallic sheen. It wants bright indirect light, high humidity and a light, free-draining mix kept just moist. A compact, spreading foliage plant, it dislikes direct sun, cold drafts and soggy crowns.
Growth habit: Rhizomatous rex-cultorum type with a short creeping rhizome producing a mound of large, asymmetrical, velvet-textured leaves.
Watch for — Leaf scorch: Direct sun burns and fades the dark velvety leaves. Move to bright indirect light.
What fertiliser begonia 'black velvet' actually wants — and why
Begonia 'Black Velvet' is a genuinely hungry tropical — in bright warmth it pushes growth fast and rewards a regular half-strength balanced feed all season.
A balanced liquid feed (even N-P-K) or a slightly nitrogen-leaning foliage feed — this is a big-leaved foliage plant putting on real size, so it wants steady nitrogen for lush leaves, not a bloom 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 begonia 'black velvet': 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 begonia 'black velvet', 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 begonia 'black velvet':
Feed every 3-4 weeks in spring and summer with a balanced liquid houseplant fertiliser at half strength. Stop feeding in autumn and winter during dormancy. For a fast grower like this that means feeding regularly — about every 3-4 weeks — right through spring through early autumn (roughly March to September), tapering off only as light drops in autumn.
The dormant-season rule matters more than the exact interval: skip feeding entirely when begonia 'black velvet' 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 begonia 'black velvet'
Half strength every feed is the sweet spot for begonia 'black velvet': frequent enough to fuel fast growth, dilute enough that it never scorches even when you feed often.
Feeding always goes onto already-damp soil, never dry roots — water begonia 'black velvet' first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the begonia 'black velvet' watering schedule.
Signs you are over-feeding begonia 'black velvet'
Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for begonia 'black velvet':
- Brown, scorched leaf tips and margins despite correct watering.
- A white salt crust on the soil or around the pot edge.
- Sudden leaf yellowing and drop shortly after a strong feed.
- Soft, weak, over-stretched growth that cannot support itself.
Signs you are under-feeding begonia 'black velvet'
- New leaves coming in noticeably smaller than older ones.
- Pale, yellow-green older leaves and slow growth through peak summer.
- A general loss of vigour and gloss in a plant that should be racing away.
If the symptoms point at watering, light or roots rather than nutrition, the full begonia 'black velvet' care brief covers soil, humidity and the common problems for this species.
Flushing and leaching the salts
Because you feed often, salts accumulate faster — flush the pot of begonia 'black velvet' with plain water until it drains freely roughly every month through the feeding season to keep the root zone clean.
Organic vs synthetic feeds for begonia 'black velvet'
Organic options
A diluted seaweed or fish-and-seaweed feed plus a yearly top-dress of worm castings supports fast growth without burn risk. UK: Westland seaweed or Baby Bio Organic; US: Neptune's Harvest or Espoma Indoor!.
Synthetic / liquid feeds
A balanced houseplant liquid at half strength applied frequently — UK: Baby Bio, Phostrogen or Westland Houseplant Feed; US: Miracle-Gro Indoor Plant Food or Dyna-Gro Foliage-Pro for steady leafy growth.
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 begonia 'black velvet' — frequently asked questions
What fertiliser does begonia 'black velvet' need?
A balanced liquid feed (even N-P-K) or a slightly nitrogen-leaning foliage feed — this is a big-leaved foliage plant putting on real size, so it wants steady nitrogen for lush leaves, not a bloom formula. Begonia 'Black Velvet' is a genuinely hungry tropical — in bright warmth it pushes growth fast and rewards a regular half-strength balanced feed all season.
How often should I feed begonia 'black velvet'?
Feed every 3-4 weeks in spring and summer with a balanced liquid houseplant fertiliser at half strength. Stop feeding in autumn and winter during dormancy. Feed every 3-4 weeks in spring and summer with a balanced liquid houseplant fertiliser at half strength. Stop feeding in autumn and winter during dormancy. For a fast grower like this that means feeding regularly — about every 3-4 weeks — right through spring through early autumn (roughly March to September), tapering off only as light drops in autumn.
What strength of feed for begonia 'black velvet'?
Half strength every feed is the sweet spot for begonia 'black velvet': frequent enough to fuel fast growth, dilute enough that it never scorches even when you feed often.
What does over-feeding begonia 'black velvet' look like?
Brown, scorched leaf tips and margins despite correct watering. A white salt crust on the soil or around the pot edge. Sudden leaf yellowing and drop shortly after a strong feed. Soft, weak, over-stretched growth that cannot support itself. The mistake here is the opposite of most houseplants: under-feeding a fast tropical in peak season starves it, leaving small, pale new leaves and slow growth — but full-strength doses still burn it, so feed often and weak, not occasionally and strong.
Should I flush the soil of begonia 'black velvet'?
Because you feed often, salts accumulate faster — flush the pot of begonia 'black velvet' with plain water until it drains freely roughly every month through the feeding season to keep the root zone clean.
Keep reading
- Begonia 'Black Velvet' care — the full brief (light, soil, humidity, problems, pet safety)
- How often to water begonia 'black velvet' — 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 snake plant
- How to fertilise dracaena
- How to fertilise peperomia
- All 2464 fertilising guides in the Growli library