Fertilising guide
How to fertilise Orchid (Phalaenopsis spp.)— schedule & NPK
Also called moth orchid, phalaenopsis.
About Orchid
Phalaenopsis spp. · also called moth orchid, phalaenopsis · flowering
Moth orchid (Phalaenopsis) is by far the most-grown houseplant orchid — easier than its reputation suggests once you understand it is an epiphyte, not a soil plant. Bright indirect light, weekly watering, and bark medium are the pillars of care. Pet-safe by ASPCA standards.
Phalaenopsis (moth orchid) species are mostly epiphytes that grow in fast-draining pockets of debris on tree branches below the leaf canopy, in warm, humid tropical forests — not in soil.
Feed 'weakly, weekly' with a balanced 20-20-20 fertilizer at about quarter strength, and flush the pot monthly with plain water to clear accumulated fertilizer salts.
Growth habit: Epiphytic monopodial evergreen
What fertiliser orchid actually wants — and why
Orchid 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.
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.
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 orchid: 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 orchid, 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 orchid:
Quarter-strength orchid feed weekly while in active growth ("weakly weekly"). Skip during winter rest. The pattern that matters: feed little and often through active growth and budding — weekly — 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 orchid 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 orchid
Very dilute — quarter strength, the classic "weakly, weekly" approach for orchid. 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 orchid first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the orchid watering schedule.
Signs you are over-feeding orchid
Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for orchid:
- 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 orchid
- 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 orchid 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 orchid 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 orchid
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 orchid — frequently asked questions
What fertiliser does orchid 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. Orchid 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 orchid?
Quarter-strength orchid feed weekly while in active growth ("weakly weekly"). Skip during winter rest. Quarter-strength orchid feed weekly while in active growth ("weakly weekly"). Skip during winter rest. The pattern that matters: feed little and often through active growth and budding — weekly — and ease right off during the rest period that triggers the next flush.
What strength of feed for orchid?
Very dilute — quarter strength, the classic "weakly, weekly" approach for orchid. These plants have fine roots that scorch easily and a steady trickle beats an occasional strong dose for flowering.
What does over-feeding orchid 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 orchid 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 orchid?
Specialist and bloom feeds leave salts that scorch fine roots — flush orchid thoroughly with plain water until it runs clear every 4-6 weeks in the feeding season, and always between feeds for orchids.
Keep reading
- Orchid care — the full brief (light, soil, humidity, problems, pet safety)
- How often to water orchid — 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 200 fertilising guides in the Growli library