Fertilising guide
How to fertilise Philodendron Imperial Red (Philodendron erubescens 'Imperial Red')— schedule & NPK
Also called Imperial Red Philodendron, Red-leaf Philodendron 'Imperial Red', Blushing Philodendron 'Imperial Red'.
More about philodendron imperial red
About Philodendron Imperial Red
Philodendron erubescens 'Imperial Red' · also called Imperial Red Philodendron, Red-leaf Philodendron 'Imperial Red' · houseplant
Philodendron 'Imperial Red' is a compact, self-heading aroid prized for glossy leaves that emerge deep burgundy-red before maturing to dark green. It thrives in bright indirect light, evenly moist soil, and warmth (18-29C). Easy to grow but toxic to cats and dogs per ASPCA, so keep it out of reach.
Growth habit: Self-heading (non-climbing) rosette habit. Leaves radiate from a short, compact central crown rather than vining, so it stays bushy and upright. New leaves unfurl glossy red to burgundy and gradually mature to deep green, often keeping reddish undersides.
Watch for — Brown, crispy leaf edges: Typically low humidity, underwatering, or salt buildup from fertiliser. Raise humidity, keep watering consistent, and flush the soil occasionally with plain water.
What fertiliser philodendron imperial red actually wants — and why
Philodendron Imperial Red 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 philodendron imperial red: 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 philodendron imperial red, 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 philodendron imperial red:
Feed every 4-6 weeks during spring and summer with a balanced, diluted (half-strength) liquid houseplant fertiliser. A urea-free formula is gentler on the roots. Stop or sharply reduce feeding in autumn and winter when growth naturally slows, and flush the soil periodically to prevent salt buildup. For a fast grower like this that means feeding regularly — about every 4-6 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 philodendron imperial red 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 philodendron imperial red
Half strength every feed is the sweet spot for philodendron imperial red: 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 philodendron imperial red first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the philodendron imperial red watering schedule.
Signs you are over-feeding philodendron imperial red
Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for philodendron imperial red:
- 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 philodendron imperial red
- 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 philodendron imperial red 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 philodendron imperial red 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 philodendron imperial red
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 philodendron imperial red — frequently asked questions
What fertiliser does philodendron imperial red 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. Philodendron Imperial Red 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 philodendron imperial red?
Feed every 4-6 weeks during spring and summer with a balanced, diluted (half-strength) liquid houseplant fertiliser. A urea-free formula is gentler on the roots. Stop or sharply reduce feeding in autumn and winter when growth naturally slows, and flush the soil periodically to prevent salt buildup. Feed every 4-6 weeks during spring and summer with a balanced, diluted (half-strength) liquid houseplant fertiliser. A urea-free formula is gentler on the roots. Stop or sharply reduce feeding in autumn and winter when growth naturally slows, and flush the soil periodically to prevent salt buildup. For a fast grower like this that means feeding regularly — about every 4-6 weeks — right through spring through early autumn (roughly March to September), tapering off only as light drops in autumn.
What strength of feed for philodendron imperial red?
Half strength every feed is the sweet spot for philodendron imperial red: frequent enough to fuel fast growth, dilute enough that it never scorches even when you feed often.
What does over-feeding philodendron imperial red 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 philodendron imperial red?
Because you feed often, salts accumulate faster — flush the pot of philodendron imperial red with plain water until it drains freely roughly every month through the feeding season to keep the root zone clean.
Keep reading
- Philodendron Imperial Red care — the full brief (light, soil, humidity, problems, pet safety)
- How often to water philodendron imperial red — 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 389 fertilising guides in the Growli library