Fertilising guide
How to fertilise Rubber plant (Ficus elastica)— schedule & NPK
Also called rubber tree, rubber bush, Indian rubber fig.
About Rubber plant
Ficus elastica · also called rubber tree, rubber bush · tropical
Rubber plant is a glossy-leaved tropical tree from Southeast Asia, easier than its fiddle-leaf cousin but still dramatic about being moved. It can grow into a 2 m living-room specimen with bright indirect light and consistent watering. Toxic to pets.
Ficus elastica is native to the tropical forests of South and Southeast Asia, from northeast India and Nepal through Myanmar to Malaysia and Indonesia, where it grows into a massive banyan-type tree with aerial roots and often begins life as an epiphyte.
A relatively vigorous grower that responds to regular balanced feeding through spring and summer, with feeding reduced or stopped in the low-light winter months.
Growth habit: Single-trunk or branched evergreen tree
Watch for — Brown patches on leaves: Sunburn or cold draught damage.
Sources: aspca.org, petpoisonhelpline.com, healthyhouseplants.com
What fertiliser rubber plant actually wants — and why
Rubber plant 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 rubber plant: 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 rubber plant, 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 rubber plant:
Balanced liquid feed at half strength every 4 weeks during the growing season. For a fast grower like this that means feeding regularly — about every 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 rubber plant 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 rubber plant
Half strength every feed is the sweet spot for rubber plant: 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 rubber plant first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the rubber plant watering schedule.
Signs you are over-feeding rubber plant
Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for rubber plant:
- 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 rubber plant
- 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 rubber plant 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 rubber plant 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 rubber plant
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 rubber plant — frequently asked questions
What fertiliser does rubber plant 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. Rubber plant 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 rubber plant?
Balanced liquid feed at half strength every 4 weeks during the growing season. Balanced liquid feed at half strength every 4 weeks during the growing season. For a fast grower like this that means feeding regularly — about every 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 rubber plant?
Half strength every feed is the sweet spot for rubber plant: frequent enough to fuel fast growth, dilute enough that it never scorches even when you feed often.
What does over-feeding rubber plant 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 rubber plant?
Because you feed often, salts accumulate faster — flush the pot of rubber plant with plain water until it drains freely roughly every month through the feeding season to keep the root zone clean.
Keep reading
- Rubber plant care — the full brief (light, soil, humidity, problems, pet safety)
- How often to water rubber plant — 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 monstera
- How to fertilise pothos
- How to fertilise fiddle leaf fig
- All 200 fertilising guides in the Growli library