From healthy growth to vibrant foliage and blooming flowers, fertilising your indoor green babies with the right indoor plant fertiliser yields a multitude of wondrous benefits!

If you want to nurture your indoor botanical companions by incorporating plant food into your plant care routine, dig into our complete guide.

Rooted in expert knowledge, the Local Botanist team has created this helpful article to direct you through the essential practice of fertilising indoor plants. Keep reading to unearth the important role of fertiliser, explore our top tips, discover different types of plant food, and much more! 

Why Is It Important to Fertilise Indoor Plants?

Fertiliser is an indoor plant food elixir that has a transformative impact on plants. Incorporating it into your plant care routine won’t just help your plants grow faster. It will also ensure they are healthy and vibrant, allowing you to achieve a lush indoor oasis!

Because indoor plants live in a controlled environment, they lack the natural nutrient cycling in outdoor soils, meaning their available nutrients can deplete over time. Applying a fertiliser will revitalise your indoor plant’s soil, ensuring their vitality is supported.

When Should You Fertilise Indoor Plants?

The optimal time to apply plant food is during the growing season (the beginning of spring to late summer). This is the period when your plants will be actively growing. As such, this results in their roots exhausting nutrients much faster than usual. Fertilisers will ensure they remain nourished and happy during this phase, contributing to healthy development.

In general, we recommend you apply plant food every other week or monthly. However, the frequency and amount of fertiliser you apply depends on the plant species and the fertiliser formula used.

Much like over-watering or over-exposure to light, too much fertiliser can harm your plant. So, it’s crucial to always check labels and follow the recommended dosage.

8 Common Types of Indoor Plant Food

From granular pellets to liquid indoor plant food, fertiliser comes in many formulas that pack all the nutrients and trace elements, such as magnesium, zinc, and copper, needed to support healthier foliage and growth. 

Familiarising yourself with the many types of plant food available will empower you to support the needs of your indoor plants. Here are the most common types worth knowing:

  1. All-Purpose Liquid Fertiliser: Featuring a balanced mix of essential nutrients, this formula is the most versatile fertiliser that’s suited to most indoor plants.
  1. Granular Fertiliser Pellets: Formulated with slow-release pellets for gradual nutrient release, this formula is ideal for plants with lower fertiliser needs, such as hardy-growing plants.
  1. Water-Soluble Powder Fertiliser: Suitable for plants that need a quick boost of nutrients, such as flowering, foliage, and tropical varieties.
  1. Organic Fertilisers: Derived from organic sources, such as compost, seaweed, and fish emulsion, this type is the perfect solution for eco-conscious gardeners seeking a sustainable alternative with naturally occurring nutrients. It’s particularly beneficial for edible plants, like herbs and vegetables, and other varieties that thrive on rich nutrients.
  1. Cactus and Succulent Fertiliser: This fertiliser is specifically formulated for cacti and succulents, often with lower nitrogen levels and a higher concentration of potassium and phosphorus to promote steady growth, healthy root development, and flowering.
  1. Liquid Seaweed Fertiliser: Featuring an organic composition of growth hormones and micronutrients, this liquid plant food is best applied to flowering and tropical plants that require a little extra care.
  1. Slow-Release Fertiliser Sticks: A convenient option for indoor plants that need a steady and slow release of nutrients, such as indoor tree species like potted palms.
  1. Fertiliser Spikes: An excellent solution for plants that require a consistent and controlled release of nutrients over a longer period, such as foliage species.

Top Tips for Fertilising Indoor Plants

Bougainvillea indoor plant

To help you get started with fertilising your indoor plants, be sure to follow our expert tips below:

  • Know Your Plants: Different species will need different types and amounts of fertiliser. So you must check the specific nutrient requirements, such as the correct ratio and formula type, of your indoor plants before giving them any plant food.
  • Make Seasonal Adjustments: Adjust your fertilising routine based on the seasons. For instance, most plants are dormant (meaning they don’t grow) during the winter. So they don’t need any fertiliser during this period.
  • Water Before Fertilising: Ensure the soil is moist before applying fertiliser to encourage better nutrient absorption and prevent potential root damage.
  • Monitor Plant Response: Keep a close eye on your plants for signs of over-fertilisation or deficiencies. Yellowing leaves, browned/blackened roots, and defoliation are common signs of overfertilisation. If you notice these symptoms, try flushing the soil or repotting your plant.
  • Establish a Regular Feeding Schedule: Creating a consistent feeding schedule, whether it’s monthly or bi-monthly, will help you maintain steady nutrient levels without causing fluctuations in the soil that will otherwise disturb your plant.
  • Avoid Fertilising Stressed Plants: If your plants are stressed due to pests, diseases, or environmental issues, refrain from applying fertiliser as this will further disrupt its well-being. Always focus on solving any underlying problems causing stress before applying fertilisers.
  • Flush the Soil: Occasionally, flush the soil with water to remove any excess salts that can accumulate from fertilisers. This will prevent salt buildup, which can harm your plant’s roots.

Plant Fertiliser vs Plant Tonic: What’s The Difference?

While both fertilisers and plant tonics deliver beneficial compounds to plants, they target different areas of plant health. Here’s a breakdown to clarify what each supplement does:

Fertiliser: A nutrient-rich solution available in many formulas, designed to nourish plants and support healthy, steady growth. Fertilisers are applied during the growing season.

Plant Tonic: An organic solution containing a micronutrient blend of minerals. This intends to promote the overall resilience, stress resistance, and well-being of plants. You can apply Plant tonics throughout the year.

Routinely feeding your plants fertiliser and plant tonic will holistically nourish them. This ensures your indoor garden is vibrantly thriving and resilient.

FAQs:

Here are some readily answered frequently asked questions about applying fertiliser to indoor plants:

What Is the Best Food for All Plants?

The three key ingredients that ensure plant health are potassium, nitrogen, and phosphorus. Other essential micronutrients include minerals, such as iron, magnesium, and zinc — some plant foods also contain additional trace elements, including calcium, copper, and manganese. 
Providing your plants with a well-balanced plant food will ensure your plants receive a complete spectrum of these nutrients, supporting their health and vitality.

What Houseplants Don’t Like Fertiliser?

Succulents and cacti don’t like general fertilisers, such as all-purpose liquid formulas, as they contain too much nitrogen. It’s best to feed your succulents and cacti a specialised formula to prevent issues, such as excessive growth and root damage. 

How Often Do I Need to Fertilise My Indoor Plants? 

When fertilising your houseplants, always check the needs of the species, and the recommended dosage provided on the fertiliser label/instruction leaflet. In general, most plants appreciate being fed once every 2 to 3 months, or even monthly, during the growing season (spring and summer).