Long Life Fungus Gnat Nematodes 20sq.m (280g)

Long Life Fungus Gnat Nematodes 20m² are a slow release way to target fungus gnat larvae in compost and soil around houseplants, greenhouse plants and outdoor containers.

The granules contain beneficial nematodes inside a hydrogel pearl, so there is no mixing required before use. Once watered in, the pearls break down gradually and release nematodes into the growing media where fungus gnat larvae live. 

Suitable for indoor and outdoor use.

Long Life Fungus Gnat Nematodes for houseplants, pots and containers

Fungus gnats can become a problem where compost stays damp, especially around seedlings, houseplants and greenhouse crops. These long life nematodes are designed for use around plant stems on the soil surface, helping you treat the area where larvae develop. They contain 10 million nematodes and are a mix of Steinernema feltiae and Steinernema carpocapsae.

How Long Life Fungus Gnat Nematodes work in the compost

Each pearl contains thousands of beneficial nematodes held inside a hydrogel capsule. After watering, the pearls gradually break down and release the nematodes into the soil, providing a simple way to apply biological control without preparing a liquid mix.

How often to reapply Long Life Fungus Gnat Nematodes

Like all nematode treatments, reapplication is needed to maintain control. Reapply every few weeks or as needed, especially in warm, humid indoor environments where gnats tend to thrive. The benefit of the long life format is that you can buy in advance and store the product until you are ready to apply, giving you more flexibility over your treatment schedule.

How to apply Long Life Fungus Gnat Nematodes

Apply approximately 0.5 teaspoon, around 5g, per plant to the soil surface around the stems. Water thoroughly after application. Keep the soil moist for 3 to 4 weeks and do not allow it to dry out during this period.

When to use fungus gnat nematodes for best results

Apply in the evening or during overcast or rainy weather. The minimum soil temperature should be 5°C. This makes the treatment suitable for use across much of the growing season, depending on conditions. If applying indoors then time of application doesn't matter. Outdoors, they are best applied between April and August.

Suitable for indoor and outdoor plant areas

These fungus gnat nematodes can be used indoors and outdoors, making them suitable for houseplants, conservatories, greenhouses, patio pots, planters and other planted containers where fungus gnats breed in damp compost.

Pack size and coverage

This pack treats up to 20m², weighs approximately 280g, and treats around 50 plants. The pack can also be used in stages if required, helping you spread applications across smaller groups of plants.

(Current batch expires 03/08/2026)

No need for refrigeration.

They contain 10 million nematodes and are a mix of Steinernema feltiae and Steinernema carpocapsae.

Storage information

Store in the original breathable packaging in a cool place, away from direct sunlight and heat. Do not transfer the contents to an airtight container. The expiry date on the pack tells you how long the product can be stored before use.

Frequently asked questions

Why are they called "long life"?

The name refers to the extended shelf life of the product. Standard nematodes must be used soon after purchase, while long life nematodes can be stored and used flexibly any time before the expiry date. You do not have to use them all at once. This makes them ideal if you want to buy ahead of time or apply in stages. Once applied, they work in the same way as standard nematodes. Reapply every few weeks or as needed, especially in warm, humid indoor environments where gnats tend to thrive.

Do I still need to reapply?

Yes. Like all nematode treatments, reapply every few weeks or as needed, especially in warm, humid indoor environments where gnats tend to thrive. The long life format gives you more flexibility over when you apply, but each application works in the same way as a standard nematode treatment.

What are Long Life Fungus Gnat Nematodes used for?

They are used to target fungus gnat larvae in compost and soil around houseplants, potted plants and other planted areas where damp growing media attracts gnats.

Do these fungus gnat nematodes need mixing with water first?

No. These are slow release granules, so there is no mixing required. You apply them directly to the soil surface and then water them in.

How much should I use per plant?

Apply around 0.5 teaspoon, approximately 5g, per plant around the stems on the soil surface.

How long should the compost stay moist after application?

Keep the soil or compost moist for 3 to 4 weeks after application and do not allow it to dry out.

Can I use these indoors?

Yes, they are suitable for indoor and outdoor use, so they can be used on houseplants as well as greenhouse and patio plants.

What area does one pack cover?

One pack treats up to 20m² and approximately 50 plants, depending on how it is applied.