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As The Perfect Garden readers already know, I get super excited about products that actually work, speedily putting fingers to keys to give you the heads up. We have been using professional pelargonic acid in the garden since 2016 and love it. Neudorff weedkiller and moss killer are a group of products that contain pelargonic acid and you can buy them without a license. Read on to find out what they will and won’t kill.

What is Pelargonic Acid?

Pelargonic acid is an organic compound that is found in nearly all animal and plant species and in many common foods we eat. The acid is found readily in the oils of the pelargonium and when used, breaks down rapidly in both land and water with little or no toxicity.

What’s in the Neudorff Weedkiller and Moss Killer

The Neudorff range of products contains pelargonic acid and this is the secret to its success as an extremely fast and effective weed and moss killer. Not only is it biodegradable but its glyphosate free too.

For the techy amongst you, each product, whether it’s the weedkiller Plus, Moss and Algae Killer or Cleanlawn Moss Control for Lawns all contain 186.7g/l of pelargonic acid. Each of the products is mixed at a different rate and the weedkiller concentrate contains a growth regulator that gives an added kick when knocking weeds on the head.

The weed killer is extremely fast acting, showing results within a few hours

You can see the speed at which the weedkiller works in the pictures below. Taken at a slightly different angle so that the sun was behind me.

Is Neudorff Weed Killer Organic?

Unfortunately, the answer is no. Although pelargonic acid is an organic compound, the weed killer also contains a growth regulator called maleic hydrazide which sounds horrid but is often used on fruit and vegetables like onions and potatoes to stop them from sprouting or to hold back the flowering of fruits.

Are Neudorff Products Safe for Pets and Children?

Yes. the areas are safe for children and pets once the product has dried. The ingredients do not hang around in the soil after treatment so can be planted or sown after just one day.

Ok Now for the Bad Stuff

Ok, it’s not all a bed for roses! There are a few bad points too.

Firstly Neudorff weedkillers only work on the green stuff. Pelargonic acid breaks down the cell walls but is not strong enough to penetrate bark or woody plants. Therefore, it’s very useful for spraying weeds under hedges, shrubs and roses where those beastly annuals like to grow.

If you spray perennial weeds like nettle, bindweed or ground elder with Neudorff, it is likely the leaves will die off but the root system will still be alive and could re-grow, this can include grasses too. If you do have deep perennial weeds, use Gallup weed killer or jump to our woody weed killer recommendation here.

I have written a post on killing weeds successfully Here if you need more help.

Does Neudorff Moss and Algae Killer Work?

Yes, it most definitely does. This is the most effective moss and algae killer spray I have come across. It has the added benefit of killing the weeds too. If you have a path or drive covered in weeds and moss then this product will do the job. In fact, so will the Neudorff WeedFree Concentrate, which is slightly more expensive as it contains the growth regulator to stop the shallow perennial weeds resprouting.


The Neudorff products are extremely fast-acting. The moss and algae killer will, without a doubt, kill moss and algae within a couple of days. The WeedFree weedkiller will kill the majority of weeds and in very short order. Showing visible results within an hour or two. However, it will not kill grass, deep rooted perennial or woody weeds. If you want to kill moss and weeds on a drive, path or patio then this product is well worth shelling out for.

As with all weedkillers, ensure you cover the leaves thoroughly with the spray.,