Fertilising guide

How to fertilise Kohleria (Kohleria eriantha)— schedule & NPK

Also called tree gloxinia, Kohleria, kohleria.

More about kohleria

About Kohleria

Kohleria eriantha · also called tree gloxinia, Kohleria · flowering

Kohleria eriantha is a tropical rhizomatous gesneriad with velvety, softly hairy leaves and clusters of tubular red-orange flowers freckled with yellow inside. A relative of the African violet, it flowers prolifically in warmth and bright indirect light, then rests by dying back to scaly underground rhizomes. Easy and forgiving once you respect its dormancy, it suits pots and hanging displays alike.

Growth habit: Upright to lax rhizomatous perennial with velvety leaves; stems can arch or trail, suiting both upright pots and hanging baskets. Spreads by scaly underground rhizomes and dies back during dormancy.

Watch for — Leaf spotting and marks: Cold water or droplets sitting on the hairy leaves cause pale or brown blotches. Water at the soil with tepid water and avoid wetting the foliage.

What fertiliser kohleria actually wants — and why

Kohleria is feeding to flower, not to grow leaves — it needs a higher-phosphorus / specialist bloom feed, given little and often, to set and hold its display.

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 kohleria: 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 kohleria, 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 kohleria:

Feed every 2 weeks through the growing season with a balanced or high-potassium fertiliser at half strength, or an African violet feed, to sustain heavy flowering. Stop feeding as the plant enters dormancy and resume when new shoots emerge. The pattern that matters: feed little and often through active growth and budding — every 2 weeks — and ease right off during the rest period that triggers the next flush.

The dormant-season rule matters more than the exact interval: skip feeding entirely when kohleria 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 kohleria

Very dilute — quarter strength, the classic "weakly, weekly" approach for kohleria. These plants have fine roots that scorch easily and a steady trickle beats an occasional strong dose for flowering.

Feeding always goes onto already-damp soil, never dry roots — water kohleria first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the kohleria watering schedule.

Signs you are over-feeding kohleria

Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for kohleria:

Lush green leaves but few or no flowers (too much nitrogen).
Brown, scorched leaf tips and edges — a classic fine-root burn.
White salt crust on the medium or pot, and stalled buds.
Bud blast: buds forming then shrivelling and dropping.

Signs you are under-feeding kohleria

Sparse or no flowering despite good light and the right season.
Smaller, paler new leaves and a generally weak, tired plant.
Flowers that are smaller or fade faster than they should.

If the symptoms point at watering, light or roots rather than nutrition, the full kohleria care brief covers soil, humidity and the common problems for this species.

Flushing and leaching the salts

Specialist and bloom feeds leave salts that scorch fine roots — flush kohleria thoroughly with plain water until it runs clear every 4-6 weeks in the feeding season, and always between feeds for orchids.

Organic vs synthetic feeds for kohleria

Organic options

Gentler options exist: a dilute seaweed feed (mildly potassium-rich) or worm-casting tea. UK: Westland seaweed, or a dilute tomato feed like Tomorite for bud-formers; US: Espoma Orchid! / Violet! or Neptune's Harvest. Lower burn risk, slower response.

Synthetic / liquid feeds

A species-matched bloom feed at quarter strength — UK: Baby Bio Orchid / African Violet food, or a high-potash Tomorite/Phostrogen for budding bloomers; US: Miracle-Gro Orchid or Bloom Booster, Schultz African Violet.

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 kohleria — frequently asked questions

What fertiliser does kohleria need?

A higher-phosphorus "bloom" formula or a species-specific feed (orchid food, African violet food, or a tomato-style high-potash/phosphorus liquid). A high-nitrogen general feed gives you lush leaves and almost no flowers. Kohleria is feeding to flower, not to grow leaves — it needs a higher-phosphorus / specialist bloom feed, given little and often, to set and hold its display.

How often should I feed kohleria?

Feed every 2 weeks through the growing season with a balanced or high-potassium fertiliser at half strength, or an African violet feed, to sustain heavy flowering. Stop feeding as the plant enters dormancy and resume when new shoots emerge. Feed every 2 weeks through the growing season with a balanced or high-potassium fertiliser at half strength, or an African violet feed, to sustain heavy flowering. Stop feeding as the plant enters dormancy and resume when new shoots emerge. The pattern that matters: feed little and often through active growth and budding — every 2 weeks — and ease right off during the rest period that triggers the next flush.

What strength of feed for kohleria?

What does over-feeding kohleria look like?

Lush green leaves but few or no flowers (too much nitrogen). Brown, scorched leaf tips and edges — a classic fine-root burn. White salt crust on the medium or pot, and stalled buds. Bud blast: buds forming then shrivelling and dropping. Using an ordinary high-nitrogen houseplant feed on kohleria is the headline mistake — you get a healthy-looking plant that simply refuses to bloom. The second is feeding through the rest period and breaking the dormancy cue it needs to set buds.

Should I flush the soil of kohleria?