Why Fertilising Matters
Plants growing in pots can't access the nutrients found in natural soil — they rely entirely on what's in their potting mix, which depletes over time. Regular fertilising replenishes these nutrients and keeps your plants growing strong, healthy, and vibrant.
At Potify, we want your plants to reach their full potential. Here's everything you need to know about fertilising your indoor and outdoor plants in Australia.
Understanding Plant Nutrients
Plants need three primary macronutrients:
- Nitrogen (N): Promotes leafy, green growth
- Phosphorus (P): Supports root development and flowering
- Potassium (K): Strengthens overall plant health and disease resistance
These are listed on fertiliser packaging as the NPK ratio (e.g., 10-5-5). According to ABC Gardening Australia, understanding NPK ratios helps you choose the right fertiliser for your plant's needs.
Types of Fertiliser
Liquid Fertiliser
Liquid fertilisers are fast-acting and easy to apply — simply dilute in water and apply when watering. They're ideal for houseplants during the growing season (spring and summer in Australia).
Slow-Release Granules
Slow-release granules are mixed into the potting mix or sprinkled on the soil surface. They release nutrients gradually over several months, making them low-maintenance and great for outdoor plants.
Organic Fertilisers
Organic options like worm castings, compost, and seaweed solutions are gentle on plants and improve soil health over time. Seaweed fertiliser is particularly popular in Australia and is recommended by Gardenate for boosting plant resilience.
When to Fertilise
Fertilise during the active growing season — spring and summer in Australia. Reduce or stop fertilising in autumn and winter when most plants slow their growth. Over-fertilising during dormancy can burn roots and damage your plant.
A general guide for Australian conditions:
- Spring: Start fertilising monthly as growth picks up
- Summer: Fertilise every 2–4 weeks for fast-growing plants
- Autumn: Reduce to every 6–8 weeks
- Winter: Stop or fertilise very lightly once every 2 months
How to Fertilise Correctly
- Always water your plant before fertilising — never apply fertiliser to dry soil as it can burn roots
- Follow the dosage instructions on the packaging — less is more
- Apply liquid fertiliser to the soil, not the leaves
- Flush the soil with plain water every few months to prevent salt build-up from fertilisers
Signs Your Plant Needs Fertilising
- Pale or yellowing leaves despite adequate light and water
- Slow or stunted growth during the growing season
- Small, weak new leaves
- Older leaves dropping prematurely
Signs of Over-Fertilising
- Brown, crispy leaf tips and edges
- White crust forming on the soil surface (salt build-up)
- Wilting despite moist soil
- Sudden leaf drop
The Royal Horticultural Society advises that over-fertilising is just as harmful as under-fertilising — always err on the side of caution.
Fertilising by Plant Type
Tropical Foliage Plants (Monstera, Pothos, Philodendron): Use a balanced liquid fertiliser (e.g., 10-10-10) every 2–4 weeks in spring and summer.
Succulents & Cacti: Fertilise sparingly — once in spring with a low-nitrogen fertiliser is usually enough.
Palms: Use a slow-release palm fertiliser in spring and summer. Palms are sensitive to over-fertilising, so follow dosage carefully.
Flowering Plants: Use a high-phosphorus fertiliser to encourage blooms.
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