Essential guide to natural fertiliser for indoor plants and indoor plant care

Introduction

Indoor plants bring life and vibrancy into our homes, improving air quality and creating a calming atmosphere. However, to thrive indoors, house plants need proper nourishment. Just like outdoor plants, they require essential nutrients such as nitrogen, phosphorus, and potassium to maintain healthy growth. BUT, let's not forget microbes! Healthy soil biology is just as important as nutrients themselves, and using biologically alive fertilisers ensures your plants receive everything they need to truly thrive.

In this guide, we’ll explore the best natural fertilisers for indoor plants, including natural fertilisers, compost, and slow-release options. We’ll also focus on how biologically active fertilisers, like Food2Soil, can provide the most effective and sustainable nourishment for your indoor plants.

 

Why do indoor plants need fertiliser?

Unlike outdoor plants, which can draw nutrients from the soil and natural cycles, houseplants rely entirely on their potting mix. Over time, these nutrients deplete, leaving plants hungry for essential nourishment. Fertilising provides the necessary boost of nitrogen, phosphorus, potassium, and, just as crucially, beneficial microbes that support plant health, flowering, and strong root development.

Signs your indoor plants need fertilising

  • Yellowing or pale leaves
  • Stunted growth
  • Weak or leggy stems
  • Loss of leaves
  • Poor flowering

 

Best natural fertilisers for indoor plants: liquid, granular, and compost

1. Best liquid fertilisers for indoor plant food

Liquid fertilisers are an excellent choice for indoor plant food as they provide nutrients quickly and can be easily diluted. The best options are those that contain both essential nutrients and living microbes to promote soil and plant health. Some popular biologically alive options include:

  • Food2Soil All-Purpose biofertiliser: A liquid biofertiliser teeming with beneficial microbes and nutrients, promoting strong root systems, lush foliage, and overall plant health.
  • Compost tea: Made by steeping compost in water, this liquid plant food provides beneficial microbes and organic nutrients.
  • Worm castings tea: A nutrient-rich solution from vermicompost, packed with essential nutrients and microbes that enhance soil biology.
  • Seaweed fertiliser: Rich in trace elements, seaweed-based plant food is best combined with microbial-rich fertilisers for a full-spectrum approach, such as the Food2Soil All-Purpose Biofertiliser with added Seaweed.
  • Molasses fertiliser: Supplies beneficial microbes with a sugar boost while adding trace elements.

💡 Tip: Always dilute liquid fertilisers before application to avoid root burn and ensure even distribution. Use them when you water your plants for easy absorption.

2. Best granular fertilisers for indoor plants

Granular fertilisers release nutrients gradually, making them ideal for long-term nourishment. Opting for biologically active granules ensures that your plant benefits from a continuous supply of nutrients and beneficial microbes. Organic options include:

  • Worm castings: Not only packed with nutrients but also loaded with beneficial microbes that enhance soil structure and plant resilience.
  • Bone meal: High in phosphorus, promoting strong roots and flower development, but works best when combined with microbial-rich fertilisers (noting that these can be a little stinky so not always great for inside!) .
  • Blood meal: A natural nitrogen source for lush, green foliage, but should be balanced with microbes to avoid nutrient imbalances (like bone meal, it can be a little on the smelly side!).
  • Rock phosphate: Supplies phosphorus for strong root growth but requires soil microbes to make it available to plants.

3. Compost and organic matter: natural fertiliser for indoor plants

Compost is one of the best ways to nourish indoor plants while also supporting a thriving soil ecosystem. Adding compost ensures your plants receive essential nutrients and beneficial microbes that help with nutrient uptake. Use:

  • Homemade compost (kitchen scraps, eggshells, coffee grounds)
  • Worm castings (nutrient-dense and great for soil structure)
  • Banana peels (potassium boost for flowering plants, especially when broken down by microbes)
  • Crushed eggshells (slow-release calcium for strong cell walls, most effective when soil microbes help break it down)

💡 Tip: Mix compost into your potting mix or sprinkle a thin layer on top to nourish your plants gradually and introduce beneficial microbes to the soil.

 

How to fertilise different types of indoor plants

Best fertiliser for indoor flowering plants

Flowering houseplants require higher phosphorus levels to support blooms. Using a biologically alive fertiliser, like Food2Soil All-Purpose Biofertiliser can be a game changer, ensuring that phosphorus is not only present but also available to the plant when needed. Compost tea and bone meal paired with beneficial microbes will also support long-lasting flowers.

Best fertiliser for indoor foliage plants

Green, leafy plants need nitrogen for lush foliage. Liquid plant food like Food2Soil All-Purpose Biofertiliser or worm castings tea is excellent for maintaining vibrant growth by providing nitrogen and microbes that improve nutrient absorption. Apply every 2-4 weeks, depending on the plant’s needs.

Best fertiliser for succulents and cacti

These plants require minimal fertiliser, but a biologically active approach can still benefit them. A diluted, balanced liquid fertiliser every 2-3 months helps strengthen root systems and maintain soil vitality. Over-fertilising can cause weak, leggy growth, so ensure microbes are present to regulate nutrient availability naturally.

Best fertiliser for herbs

Herbs like basil, mint, and thyme thrive with regular feeding. Using a liquid biofertiliser ensures a balance of nutrients and microbes, keeping your herbs productive and resilient. Apply diluted compost tea or fish emulsion every two weeks to encourage fresh, fragrant leaves.

 

Best practices for indoor plant care and fertilising

  • Water your plants before fertilising to prevent root burn and support microbe activity.
  • Follow dilution guidelines for liquid fertilisers to avoid overfeeding.
  • Fertilise during the growing season (spring and summer); reduce feeding in autumn and winter when growth slows.
  • Use foliar sprays (take your plants outside and spray with a biofertiliser, seaweed or compost tea) for quick nutrient absorption and microbial application.
  • Repot plants every 1-2 years to refresh the potting mix.

 

Common mistakes to avoid when using fertilisers for indoor plants

❌ Over-fertilising: Can lead to salt buildup and root damage, particularly if synthetic fertilisers are used without microbes to balance them.

❌ Using synthetic fertilisers: Can harm soil microbes and lead to nutrient imbalances, making biologically active fertilisers a superior choice.

❌ Ignoring different plant needs: Not all plants require the same type of fertiliser, but all benefit from a thriving microbial community.

❌ Fertilising dry plants: Always water your plants before applying fertiliser to support both nutrient absorption and microbial activity.

 

Conclusion: feed and fertilise your indoor plants for optimal growth

Providing natural, biologically alive fertiliser for your indoor plants is key to maintaining their health and vibrancy. Indoor plants are often starved of the much needed biology that occurs in soils so, whether you choose liquid fertilisers like Food2Soil All-Purpose Biofertiliser, slow-release granules, or organic compost, feeding your houseplants with the right nutrients and beneficial microbes will give your plants an amazing boost, ensuring lush foliage, strong roots, and beautiful flowers.

Remember to tailor your fertilising routine to the specific needs of different plants and enjoy the rewards of a thriving, biologically rich indoor garden. Happy planting! 🌿