Fertilising guide
How to fertilise Persian Violet (Exacum affine)— schedule & NPK
Also called Persian Violet, German Violet.
More about persian violet
About Persian Violet
Exacum affine · also called Persian Violet, German Violet · flowering
Persian violet (Exacum affine) is a compact, bushy gesneriad relative from Socotra grown as a flowering houseplant, smothered in small, fragrant, five-petalled blue-violet flowers with bright yellow stamens. It enjoys bright indirect light, evenly moist soil, warmth, and moderate humidity. Usually treated as an annual or short-lived pot plant, it blooms for months when deadheaded and not allowed to dry out.
Growth habit: Compact, bushy, mounded tender annual or short-lived perennial that flowers prolifically from a tidy dome of glossy oval leaves.
Watch for — Fewer flowers over time: Failing to deadhead and underfeeding reduce bloom; remove faded flowers regularly and feed lightly through the flowering period.
What fertiliser persian violet actually wants — and why
Persian Violet 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 persian violet: 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 persian violet, 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 persian violet:
Feed every 2 weeks while flowering with a half-strength balanced or high-potassium liquid fertiliser to sustain continuous bloom; little feeding is needed once flowering ends. Treat that as every 2 weeks 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 persian violet 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 persian violet
Half strength is the safe default for persian violet — 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 persian violet first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the persian violet watering schedule.
Signs you are over-feeding persian violet
Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for persian violet:
- 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 persian violet
- 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 persian violet care brief covers soil, humidity and the common problems for this species.
Flushing and leaching the salts
Flush the pot of persian violet 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 persian violet
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 persian violet — frequently asked questions
What fertiliser does persian violet 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. Persian Violet 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 persian violet?
Feed every 2 weeks while flowering with a half-strength balanced or high-potassium liquid fertiliser to sustain continuous bloom; little feeding is needed once flowering ends. Feed every 2 weeks while flowering with a half-strength balanced or high-potassium liquid fertiliser to sustain continuous bloom; little feeding is needed once flowering ends. Treat that as every 2 weeks 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 persian violet?
Half strength is the safe default for persian violet — houseplant feeds are formulated strong, and the diluted dose is gentler on the roots while still ample for foliage.
What does over-feeding persian violet 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 persian violet 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 persian violet?
Flush the pot of persian violet 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
- Persian Violet care — the full brief (light, soil, humidity, problems, pet safety)
- How often to water persian violet — 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 peace lily
- How to fertilise bird of paradise
- How to fertilise hoya
- All 1284 fertilising guides in the Growli library