drawing of a slug that nematodes parasite on and kill within a week

Using Nematodes for Slug Control in Organic Gardens

 If you’re anything like me, you love gardening and growing your own organic plants and vegetables. But you also know the frustration of finding your plants nibbled by slugs, or completely decimated. These slimy creatures are the bane of my garden, and I’ve tried many ways to get rid of them. Some of them worked and some of them didn’t. That’s why I was delighted the first time I tried using nematodes for slug control. In organic gardens, because a garden is essentially unnatural due to our inputs, sometimes the pest populations can become unnaturally large too so a natural and effective way to control them when they get out of hand  without harming anything else is important.

Table of Contents

What Are Nematodes and How Do They Work?

Nematodes are tiny worms that live in the soil and feed on slugs. They are harmless to humans, animals, and plants, but deadly to slugs. Here’s how they do their magic:

  • Attack: The nematodes find the slugs by following their slime trails. They enter the slugs through their mantle.
  • Kill: Once inside, the nematodes release bacteria that stop the slugs from eating and make them die within a few days.
  • Multiply: The nematodes then breed inside the dead slugs, producing more nematodes that emerge to hunt for more slugs.
  • Deters: A number of slug species, including the most common like Chestnut slugs, Three Band slugs (a real greenhouse pest), Grey garden slugs, Black slugs and Blue-Black Garden slugs all avoid areas where P. hermaphrodita nematodes are present 
  • Eco-Friendly: The best part is that these nematodes only target slugs , leaving the rest of the garden wildlife alone. They are also organic and safe for children, pets, and plants.
  • Quick Acting: Infected slugs stop eating after three days and die within 7 days (normally underground).

How to Use Nematodes in Your Garden

 Using nematodes is easy peasy and effective. 

  • Timing: Apply nematodes when the soil temperature is above 5ºC, which is usually when the slugs start to become active and your plants start to grow. Don’t worry if there is a frost after you apply them, as nematodes are tough blighters and can survive it.
  • Method: Mix the nematodes with water and spray or water them over the soil around your plants. Make sure the soil is moist but not soggy. If you have heavy clay soil, loosen it up a bit before applying nematodes.
  • Potatoes: If you grow potatoes, you know how slugs love to munch on them. To protect your spuds, apply nematodes about 6-7 weeks before you harvest them, as this is when the slugs are most likely to attack them.
  • Routine: To keep the slugs under control, use nematodes every six weeks during the growing season. This will ensure that your plants are safe from slug damage.
How to water nematodes onto a flowerbed

Why Nematodes Are Good for Your Garden

Nematodes and organic gardens go together like slugs and hostas!

  • Selective: Nematodes only kill slugs, not other beneficial insects or animals. This means that your garden will have a healthy and balanced ecosystem.
  • Long-lasting: One application of nematodes will last for at least six weeks, giving your plants enough time to grow and establish themselves.
  • Weather-proof: Nematodes work well in wet weather, which is when slugs are most active and most damaging. You don’t have to worry about rain washing away your nematodes or making them less effective. Organic: Nematodes are a natural and organic way to control slugs, without using any chemicals or pesticides. This is good for your health, your plants, and the planet.

Nematodes: The Ultimate Slug Solution

Nematodes are a wonderful way to deal with slugs in your garden. They are natural, effective, and safe, and they will help you grow healthy and beautiful plants. I’ve been using nematodes for a year now and I can honestly say that they have made a huge difference in my garden nursery. No more slugs, no more holes, no more frustration. Just lovely, organic plants that don't get munched too much!. If you haven’t tried nematodes yet, I urge you to give them a go. You won’t regret it. Nematodes are the ultimate slug solution.

FAQ Section: Navigating Nematode Applications for Organic Gardening

Question: What is a nematode?

A nematode is a tiny worm that lives in the soil and feeds on slugs. They are my best friends in the garden, as they help me get rid of those pesky slugs that eat my plants. They are very clever, as they find the slugs by following their slime trails and then enter their bodies and kill them from the inside.

Question: Why use nematodes?

Nematodes are a natural and organic way to control slugs, without using any chemicals or pesticides. They are safe for children, pets, and wildlife, and they don’t harm the plants or the soil. They are also very effective, as they can reduce the slug population by up to 80% in just a few weeks.

Question: How do I apply nematodes?

Applying nematodes is very easy. You just need to mix them with water and spray them over the soil around your plants. You can use a watering can with a coarse rose or a hose-end feeder. The instructions are on the packet, and they are very simple to follow.

Question: When can I apply nematodes?

You can apply nematodes when the soil temperature is above 5ºC (40ºF), which is usually when the slugs start to become active and your plants start to grow. I usually apply them in early spring, when I sow my seeds or plant my seedlings, and then again in late summer, when I harvest my crops.

Question: What will nematodes control?

Nematodes will control most types of slugs that you find in your garden, especially the small and medium ones that are up to 8 cm (about 3 inches) long. They are very good at dealing with the young slugs that hide in the soil and attack your seedlings.

Question: How long do nematodes work for?

Nematodes will work for at least six weeks after you apply them, which is enough time for your plants to grow and establish themselves. The nematodes will also multiply inside the dead slugs, producing more nematodes that will hunt for more slugs.

Question: Are there any special precautions?

The only thing you need to be careful about is not to apply nematodes near ponds or water features, as they might harm the aquatic snails that live there. You should keep a distance of about 15cm (6 inches) from the water’s edge when you spray the nematodes.

Question: Can nematodes be used on clay soils?

Nematodes can be used on any type of soil, as long as it is not too compacted, waterlogged, or heavy wet clay. If you have clay soil, you should loosen it up a bit and add some organic matter before you apply the nematodes. This will make the soil more aerated and allow the nematodes to move around more easily.

Question: Are any special conditions required?

The only thing you need to make sure is that the soil is moist when you apply the nematodes, especially in hot weather. This will help the nematodes to survive and reach the soil. You should also avoid applying them in the middle of the day, when the sun is too strong and might dry them out. The best time is in the morning or evening, when the temperature is cooler.

Question: What happens if the temperature falls after I have used nematodes?

Nematodes are quite tough and can survive a bit of frost. If the temperature drops after you have used them, they might slow down a bit, but they won’t stop working. They will still kill the slugs, just a bit more slowly.

Question: Are nematodes washed out of the soil during prolonged wet weather?

Nematodes are not affected by wet weather, in fact, they like it. They will continue to work well during rainy periods, as this is when the slugs are most active and most damaging. You don’t have to worry about the rain washing away your nematodes or making them less effective.

Question: Is it beneficial to apply nematodes in the autumn?

Yes, it is. Applying nematodes in the early autumn can help you reduce the number of slugs in the next spring, as you will prevent them from laying eggs in the soil. This will make your life easier when you start your gardening in the new season.

Question: Can I water nematodes onto plants directly?

It is better to apply nematodes to the soil, as this is where they live and where they find the slugs. If you have a lot of plants that cover the soil, you can water the nematodes onto the foliage, but you should then water them again to make sure they reach the soil. Otherwise, they might dry out and die on the leaves.

Question: Can I eat produce that has been treated with nematodes?

Of course, you can. Nematodes are harmless to humans, animals, and plants, and they don’t leave any residues on your produce. You can eat your fruits and vegetables as you normally would, just wash them before you do.

Question: Can nematodes kill snails?

Nope. The commercially available treatment that uses P. hermaphrodita nematodes does not affect their survival or feeding, and they do not avoid the area in the same way slugs do. Thing is I've never gone to check my plants at night and found them covered by snails so no biggie.

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