Best Fertilizer for Rubber Plant: Feeding Your Ficus Elastica the Right Way

Rubber plants (Ficus elastica) are popular indoor foliage plants known for their broad, glossy leaves and upright growth habit. Also called rubber trees or rubber figs, they are low-maintenance, but proper feeding is essential for healthy growth, leaf colour, and resilience.

Ficus elastica originates from tropical regions and adapts well to indoor environments, thriving in bright, indirect light and well-draining soil. As fast growers under the right conditions, they can reach impressive heights indoors, especially when given regular fertilisation. The best fertilizer for rubber plants should support foliage density, stem strength, and root development without encouraging spindly or overly rapid growth.

Rubber plants require a balance of the three major macronutrients: nitrogen (N) for lush green leaves, phosphorus (P) for root and stem health, and potassium (K) for structural strength and disease resistance. A complete liquid fertiliser with a balanced NPK ratio helps promote uniform growth and leaf sheen throughout the year.

Because rubber plants are typically grown indoors, they rely entirely on you for their nutrient supply. Potting mixes deplete over time, and even high-quality soil loses nutrients with each watering. That’s why liquid feeding is so effective—it ensures consistent delivery of essential nutrients in a format that’s quickly absorbed by the plant’s roots.

Without proper fertilisation, rubber plants may exhibit slow growth, pale or yellowing leaves, and weak stems. On the other hand, overfeeding with the wrong formulation can lead to leaf burn, excessive stretching, or salt buildup in pots. Choosing a balanced, indoor-safe fertiliser is key to maintaining a strong, visually striking rubber plant year-round.

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How to Fertilize Rubber Plants Indoors for Best Results

To fertilize a rubber plant effectively, begin feeding in early spring and continue through the warmer months. During this active growth period, apply a balanced liquid fertiliser every 2 to 4 weeks. Choose a formulation that dissolves fully in water and can be delivered directly to the root zone via watering can or spray bottle.

Always water your rubber plant before applying fertiliser. This protects the roots from nutrient burn, especially in compact or dry soil. Apply the diluted solution evenly around the base of the plant, avoiding the leaves unless the product is labeled for foliar feeding. Rubber plants absorb nutrients quickly when the soil is slightly moist and temperatures are above 18°C.

During late autumn and winter, reduce fertilising to once every 6–8 weeks or pause altogether if the plant’s growth slows. Indoor rubber plants typically go semi-dormant in lower light conditions. Feeding too frequently during this period can lead to weak, pale growth and nutrient imbalance.

Pruning or repotting is a good time to reintroduce a feeding routine. After pruning, a dose of liquid fertiliser encourages branching and regrowth. After repotting, wait 2–3 weeks for root recovery before fertilising again. For plants in low-light corners, fertilise less often to avoid stretching or leggy growth.

Signs that your rubber plant needs fertilising include slowed growth, smaller new leaves, dull leaf colour, and yellowing along leaf edges. A properly fertilised rubber plant should maintain upright stems, large glossy leaves, and steady growth throughout spring and summer. Use a clean watering tool and flush the soil every few months to prevent salt buildup.

Fertilising Tips, FAQs, and the Best Indoor Fertiliser for Rubber Plants

Feeding your rubber plant consistently throughout its growing season will improve leaf size, colour, and structure. Use a complete fertiliser tailored to indoor foliage plants and avoid granular or outdoor-use products, which may be too strong for potted conditions. Always monitor for signs of overfeeding, including brown leaf tips or crusty white salt deposits on the soil surface.

Keep your plant in a well-lit location to complement your fertiliser routine—rubber plants in darker spaces will absorb fewer nutrients and may suffer from stretched stems or thin foliage. Rotate the pot every few weeks to ensure balanced exposure and uniform growth.

Frequently Asked Questions

What is the best fertilizer for rubber plant?
A balanced liquid fertiliser designed for indoor plants is ideal. Look for one with nitrogen, phosphorus, potassium, and micronutrients for foliage health and strong growth.
How often should I fertilize a rubber plant?
Every 2–4 weeks during spring and summer. In winter, reduce or stop feeding depending on light conditions and plant activity.
Why are the leaves on my rubber plant turning yellow?
This may be due to underfeeding, overwatering, or poor light. Start with a balanced liquid fertiliser and evaluate your watering and lighting conditions.
Can I use outdoor plant fertiliser on my indoor rubber plant?
It’s not recommended. Indoor-specific liquid fertilisers are gentler and designed for controlled environments where salt buildup is a concern.

Recommended Fertiliser: For lush, glossy leaves and consistent growth, we recommend CompleteGrow’s Indoor Plant Food Concentrate Fertiliser. This liquid formula is perfect for rubber plants and other indoor foliage, delivering complete nutrition in a low-risk, fast-absorbing blend.