More about Nematodes - your questions answered

We get loads of questions about nematodes, how they work and their safety, here we address the most common ones.

What are nematodes and where do they come from?

Nematodes are microscopic eelworms and they are naturally occuring in the soil.  They are target specific, meaning that each species only has one pray.  The ones we sell are mass produced on artificial diets.  They are produced in the UK, on the south coast.

Don't nematodes affect plants and humans?

Lots of people ask why the nematodes we sell are not harmful to plants, humans or wildlife.  There are many many species of nematode in the natural world but they are all target specific.  We sell nematodes for specific garden pests and they do not affect anything else.  By applying nematodes to you are garden you are boosting a population that is already there without upsetting the delicate ecosystem.

Are nematodes safe for dogs?

Yes, you can allow dogs, other pets, children to play on treated areas immediately as our nematodes are 100% biological and safe.  Read more about dogs and slugs here...

Are nematodes ok to use on edible crops and in organic gardening?

Yes, nematodes are 100% biological and there both safe for edibles and endorsed for use in organic gardening by The Soil Association.

Can you see nematodes?

Nematodes are tiny, microscopic colourless worms so they can't be seen with the naked eye.

How do nematodes work?

Nematodes work by infecting the host with a lethal bacteria.  They enter via the digestive or respiratory system of the pest and stop that from working.  This stops the pest from feeding within 48 hours and eventually kills the pest within a few days.  They reproduce inside the pest and release further generations into the soil.  You can find out more about how they work here...

Do nematodes kill snails?

The species of nematode that kills slugs works on the sugs underground so does not have the ability to kill snails.  Slugs and snails are seen to avoid areas treated with Nemaslug nematodes so they can be used as a natural deterrent to keep snails numbers down in your garden.

Why are nematodes more effective against slugs than pellets, traps or barriers?

There are up to 95% more slugs in your garden then you ever see as the vast majority live underground.  Only nematodes will reach this part of the population and stop then decimating the roots of your plants or making their way to the surface to do that damage above ground.

When should I treat with nematodes?

When to use nematodes depends on a few factors; which pest you are dealing with, the soil temperature where you are and your diary!  Nematodes for slugs and vine weevil can be used when the soil temperature reaches 5°C.  Nematodes for other pests can be used from 10°C.

What time should I apply nematodes?

As it's important that the soil, or plant if using as a foliar spray, must not dry out after nematodes application it's often best to apply late in the day and out of direct sunlight.  Once you have opened the package and mixed up the solution you only have a few hours to carry out the application.  The nematodes will drown if left too long.

You also don't want to apply nematodes then go away for a few days as you will need to make sure to keep the area damp.  To save you some time, and water, it's a good idea to look at the weather forecast and plan to do your application when rain is due.

Which nematode species do I need?

Luckily our nematodes are named according to the pest that you are dealing with but here's a quick rundown;

Slugs - Nemaslug containing the species Phasmarhabditis Hermaphrodita, available in 40 and 100 square metre packs.

Vine Weevil - Nemasys Biological Vine Weevil Killer containing the species Steinernema Kraussei, available in 12 and 100 square metre packs.

Leatherjackets - Nemasys Biological Leatherjacket Killer containing the species Steinernema Feltiae, available in 100 and 500 square metre packs.

Chafer Grubs - Nemasys Biological Chafer Grub Killer containing the species Heterorhabditis Bacteriophora, available in 100 and 500 square metre packs.

Fungus Gnat (Sciarid Fly), Thrips, Codling Moth, Caterpillars, Scale, Carrot and Onion Root Fly plus others - Nemasys Fruit and Veg Protection, containing 50% Steinernema Feltiae and 50% Steinernema Carpocapsae, available in 60 square metre packs. 

Can I apply two types of nematode at once?

Yes, as you can see above, nematodes are pest specific and do not interact with one another.  Do not mix the packs together, apply them separately and concentrate each application on the area the pest is.  For example vine weevils tend to be around the roots of plants.

How to apply nematodes (soil drench)

All our nematodes come with detailed instructions that should be followed to the letter so we will not go into specifics here but in preparation for receiving nematodes here's a few things you should do/make sure you have;

  • Ensure the soil or compost is well irrigated and not compacted
  • Ensure the soil is above the minimum required temperature
  • Clean the equipment you are going to use to apply the nematodes
  • Have available a watering can with a course rose or a hose end feeder for large area applications

How to apply nematodes to leaves and foliage

Some pests that live above ground can be killed off with nematodes.  Again, the instructions for doing this are in the pack.

What happens to nematodes after they have killed the pest?

Nematodes reproduce inside the pest and release further generations into the soil.  If there's not more of their prey around then they will die back to their natural levels.


If you have any other questions about nematodes and their application please get in touch via