Natural Slug Control on Trial

Like many gardeners, I want to grow flowers and vegetables as well as I can- without harming the environment. Slugs can be a problem, munching delicate seedlings overnight. So I’m trying biological controls this summer to see how effective they are.

My Nemaslug biological slug killer arrived with an ice pack to keep it cool. I’ll be able to re-use the ice pack. The polystyrene packaging will be recycled as a salad-growing container.

The package was kept in the bottom of the fridge until I had time to deal with it. Nematodes are microscopic living creatures that will survive for a limited amount of time if kept cool.

Nematodes are mixed in water and applied to moist soil. We had a period of drought, which made it difficult to use the product within its “use by” date. But finally we had rain, and I was able to get going.

The nematodes were mixed in a bucket containing 10 litres of water. This creates a stock solution. Next I added .5 litres of the stock to a 5 litre watering can of water. I paced out the vegetable plot and it took me about 20 minutes to water the whole area. The pack covered about 120sq yds. I had to go out and buy a coarse watering can rose as I didn’t have one in the potting shed. The stock solution has to be used in one session. It can’t be halved and saved for another day. So sufficient time is needed to read the instructions, measure everything out and distribute it.

Nematodes hunt down and attack slugs, releasing a bacteria that kills them. The nematodes then reproduce inside the dead slug and release a new generation to continue the work.

Here’s Grace sitting on the beds that were treated with nematodes. She’s “guarding” the broad beans against mouse attack.

Biological controls won’t harm plants, pets or any other creature. They are specific to the targeted pest.

I want to protect my potatoes, brassicas, salad and courgettes. I’m also growing sweetpeas and sunflowers. Apart from potatoes, all my plants are started off in the greenhouse and only planted out when they are a reasonable size to cope with being nibbled. Soft new growth is more attractive to slugs than tougher, older leaves.

Nematodes can only be used between March and October, when temperatures are between 5-30C. I applied my nematodes in the evening. And luckily after six weeks of drought, we had rain overnight. The nematodes need moist conditions to move through the soil to search for slugs.

On my plot , I try to garden as naturally as possible. I have an acre of woodland and wilderness where slugs are allowed to thrive and become food for birds and mammals. If I’m going to grow good food crops and cut flowers, I have to think of a way of controlling pests. Nematodes seem one way to do this without using chemicals. I’ll report back over the summer on the effectiveness of these treatments.

NOTE: I didn’t pay for this nematode pack. As always, my honest opinion is all that’s being sought. The pack sent to try out would cost between £25 and £28; however, there are various bulk buy options and special offers available. So the price is a guide line only. Less costly packs are available for smaller areas.


Have you tried nematodes? How did you fare with them in your garden? Do you think it made a difference? Please let me know, and kindly share this blog on any social media platform you use.

36 thoughts on “Natural Slug Control on Trial

  1. Nematodes really should be more commonly used than they are; and they really should be promoted more. It was something we talked about in the 1980s, and they really have not gotten much farther along.

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  2. I am trying them this year Karen – a coarse rose is definitely needed and what I had wasn’t coarse enough which slowed the process down. I will repeat the process in amonth or so’s time but might look into a spray attachment – otherwise a coarse rose which is of course the cheaper although not easier option

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  3. Thanks Karen – I think I’ll give this method a go as I’ve just planted out a large number of delphiniums I grew from seed last year and I’m worried they’re going to get eaten – obsessive inspection is the current method!

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    • Hello Phao. I would also try the wool pellets from Vitax, they are excellent. And the white granules from ecofective. Although they don’t look as good in the garden. I’m very pleased with the results so far. No nibbles on the emerging dahlia shoots or the sweet peas. Normally they are ravaged by now. Good luck with your delphiniums.

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  4. I have used them on raised veg and hosta beds. I think they help yo reduce the slug population in those specific areas. I combined it with organic slug pellets in the early spring before the temperature was right for the nematodes.

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    • Thank you Amelia. I’m weighing up the benefits against the cost. New potatoes are expensive here, and they are so much better fresh from the garden. Sunflowers are enjoyed by bees all summer,and then birds eat the seed in the winter. I’m only trying to control slugs on the veg plot. They are eaten by hedgehogs in the rest of the garden.

      Liked by 1 person

  5. Karen, please first read the two emails, before sending the gloves, which I have sent you please, it is very important, thank you very much. He had never used Nematodes in the garden, but he had heard a lot about them. Thank you very much for the clear instructions you have written as to how to use them and when to do it. It is a very interesting blog. And the link is great. Your garden and the court beds are divine. Grace is beautiful and taking care of everything half asleep! I love the forest with the pond. I trust that the Nematodes finish with the slugs in the areas where you have watered. You will tell us. Karen you are a great friend and I really appreciate your family and you. Love, health, strength and happiness for your whole family and for you. Take care and rest. Greetings very affectionate.

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  6. Good luck Karen! I haven’t tried nematodes for slugs before, but I did use them once for vine weevils in my first garden. Not sure they helped very much! I have found copper tape works well against slugs and snails around pots as long as they are on ‘feet’. And I have heard chilli powder or cinnamon are also avoided by the slimy pests – yet to try that out though!

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    • Thank you Cathy. I’m going to try the copper tape too. Have had some success with the wool pellets. And ecofective have brought out a slug deterrent made of white gritty stuff. But it looks awful in the garden. Would be better if it was soil coloured. If I find any slugs or snails I put them in our dry ditch and hope the birds eat them.

      Liked by 1 person

  7. I tried them once and they made no difference. they may work better in a specific targeted way like the way you are planning. I now rely on starting things in pots and using copper bands round very precious plants. It sort of works. Good luck with the nematodes!

    Liked by 3 people

    • Thank you. I’ll try the copper bands. I’ve started early this year. I’m going to treat them again in mid summer and again in early autumn. Trying to reduce the population on the veg plot area.

      Liked by 1 person

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