Your Guide to Using Steinernema feltiae (SF) Nematodes for Healthy, Pest-Free Soil in Malta

At TerraSoil, we’re all about building living, healthy soils that help plants thrive naturally. One of our favourite allies in the fight against soil-dwelling pests is the Steinernema feltiae (SF) nematodes. they are tiny, microscopic worm's that pack a huge punch when it comes to keeping harmful larvae under control.

Whether you’re growing vegetables, flowers, or houseplants, SF nematodes are a safe, natural, and highly effective way to keep your soil healthy. Here’s everything you need to know.

Using SF nematodes for pest control

What Are SF Nematodes?

SF nematodes are microscopic, soil-dwelling worms that naturally hunt down and kill certain insect larvae. They’re found in soils worldwide, but in a concentrated form, they can be applied as a biological control.

Once applied, they actively search for pest larvae such as fungus gnats, root weevils, thrips pupae, and more. When they find a host, they enter it, release symbiotic bacteria, and quickly kill it from the inside – breaking the pest life cycle before adults can emerge.

Why Use SF Nematodes?

• Highly Effective Pest Control – Can reduce targeted pest larvae by 80–95% in the right conditions.

• Completely Safe – Harmless to people, pets, beneficial insects, and earthworms.

• Chemical-Free – No toxic residues, perfect for organic gardening.

• No Resistance Build-Up – Unlike chemical pesticides, pests can’t adapt to nematodes.

• Supports Soil Health – Protects roots, reduces stress on plants, and encourages a balanced soil ecosystem.

Best Time to Apply in Malta

SF nematodes are most active in soil temperatures between 12°C and 25°C. In Malta’s climate, this means:

• Outdoor best windows:

  • March–May (spring)

  • October–mid-December (autumn)

• Avoid:

  • Peak summer (June–August) when soil temperatures can exceed 25°C.

  • Coldest winter weeks if soil drops below 10°C.

Indoors? You can apply SF nematodes any time of year – even now in August – as long as soil is kept moist and shaded from direct sun.

When to Use Indoors

If you’re dealing with fungus gnats, thrips pupae, or root pests in potting mixes, SF nematodes can be applied right now in Malta. Indoors, you control:

• Temperature – Pots are unlikely to overheat if shaded and watered.

• Moisture – Essential for nematode movement.

• Light – No direct UV means nematodes survive longer.

This is especially effective in late summer to stop autumn pest explosions before they happen.

How to Apply SF Nematodes

1. Pre-Water the Soil – Keep it evenly moist before applying.

2. Mix According to Instructions – Use cool, clean water.

3. Apply Evenly – Using a watering can, hose-end sprayer, or irrigation system.

4. Avoid Direct Sunlight – Apply in the evening, morning, or indoors.

5. Maintain Moisture – Keep the soil damp for 7–10 days afterward for best results.

   
   

What to Expect

• First results: Within 7–14 days, pest populations will noticeably drop.

• Full control: Within 3–4 weeks under ideal conditions.

• Repeat applications: Every 6–8 weeks or as pest activity returns.

TerraSoil Tip 🌱

For best results, combine SF nematodes with good soil care – healthy compost, balanced nutrition, and regular watering. Healthy soils help nematodes thrive and give your plants the strongest defence against pests.

In Summary

Steinernema feltiae nematodes are a grower’s secret weapon – natural, safe, and incredibly effective at tackling soil-borne pests in Malta. Whether you’re treating outdoor beds in spring or autumn, or applying indoors right now, they’re a smart choice for keeping your plants healthy without chemicals.