Soil Ninja Worm Castings | Natural Plant Fertiliser 2.5L

Soil Ninja Worm Castings are a natural, nutrient-rich soil improver and fertiliser for houseplants. Produced by earthworms as they break down organic matter, worm castings (also known as vermicompost) provide a gentle source of plant nutrients while helping to improve the structure, moisture retention and biological activity of your potting mix.

Whether you're repotting a Monstera, making your own houseplant compost or giving an established plant a little extra nourishment, worm castings are one of the simplest ways to enrich your soil naturally. Just mix them into your compost or add a little to the surface of an existing pot and water in.

What are worm castings?

Worm castings are the finely processed organic material produced by earthworms as they digest decomposing plant matter. The resulting dark, crumbly material contains naturally occurring plant nutrients, organic matter and beneficial microorganisms that contribute to healthy, biologically active soil.

Unlike many concentrated liquid fertilisers, worm castings release their nutrients gradually as organic matter continues to break down. They also help improve the soil's ability to retain moisture and nutrients, making them a valuable ingredient in both ready-made and homemade houseplant potting mixes.

Why use worm castings for houseplants?

• Natural plant nutrition: Provides a gentle supply of essential plant nutrients to support healthy growth.
• Supports healthy roots: Enriches the growing medium with organic matter and nutrients that support root development.
• Encourages beneficial microorganisms: Introduces naturally occurring microbial life that helps break down organic material and cycle nutrients through the soil.
• Improves moisture retention: Helps the potting mix hold moisture, particularly useful for plants that prefer consistently lightly moist compost.
• Improves soil structure: Adds organic matter to create a more balanced growing environment.
• Easy to use: Simply mix into compost when repotting or apply as a top dressing to established plants.
• Peat-free: A natural way to enrich your houseplant compost without adding peat.

Which plants benefit from worm castings?

Worm castings are suitable for a wide range of indoor plants, particularly tropical foliage plants that appreciate a nutrient-rich, organic growing medium.

• Monstera: Helps enrich the chunky, well-aerated compost preferred by these popular climbing plants.
• Philodendron and Pothos: A useful addition to potting mixes for healthy foliage and root development.
• Calathea and Maranta: Adds organic matter and improves moisture retention in compost for these humidity-loving plants.
• Alocasia: Provides an additional source of nutrients during active growth.
• Ferns: Particularly useful for enriching moisture-retentive potting mixes.
• Other foliage houseplants: Including peace lilies, Ficus and many other plants grown in conventional compost.

Worm castings can also be used sparingly in mixes for cacti and succulents, but take care not to compromise the sharp drainage these plants require.

How to use Soil Ninja Worm Castings

1. Mix into compost when repotting

Add approximately 10% worm castings by volume to your chosen potting mix as a useful starting point. For example, combine one part worm castings with nine parts suitable houseplant compost and mix thoroughly before potting your plant.

2. Top dress established houseplants

There's no need to repot just to give your plants a nutrient boost. Sprinkle a thin layer of worm castings over the compost surface, gently work it into the top layer if possible, and water as normal. Avoid piling the material directly against the plant's stems.

3. Refresh your potting mix

Worm castings can be incorporated into existing compost blends when repotting, helping replenish some of the nutrients and organic matter that plants gradually use up.

How often should you use worm castings?

For most houseplants, applying worm castings at the beginning of the growing season is a good starting point. Established plants can benefit from a further light top dressing during spring or summer, depending on their growth and nutritional requirements.

Worm castings are a gentle soil amendment rather than a precisely formulated fertiliser. Fast-growing or particularly hungry plants may still benefit from a suitable additional plant feed during active growth.

Are there living organisms in worm castings?

Yes! Soil Ninja Worm Castings are a living product, containing naturally occurring microorganisms and potentially small soil-dwelling creatures such as springtails or young earthworms. These are part of the natural decomposition process and are generally harmless to healthy plants.

The presence of these organisms is normal for a living soil amendment and doesn't mean the product is contaminated.

Product details

• Brand: Soil Ninja
• Product: Worm Castings
• Also known as: Vermicompost or earthworm castings
• Type: Natural fertiliser and organic soil improver
• Uses: Houseplant compost enrichment, repotting and top dressing
• Properties: Nutrient-rich, peat-free and biologically active
• Bag size: 2.5 litres

Please note: As a natural, living product, the appearance, texture and biological activity of worm castings can vary between batches.

Looking to make your own nutrient-rich houseplant compost? Explore our Soil Ninja collection for specialist potting mixes and individual soil components.