What are these black patches on my artificial grass?

What are these black patches on my artificial grass?

“What are these black patches on my artificial grass?”

“What are these black patches that look like mud or dirt on my artificial grass? I can’t get rid of them.” 


what are these black patches on my artificial grassIt’s a growth of algae and mould. Abi (the grass cleaning expert) from Top Dog Turf says don’t panic! It’s easy to treat with the right product.

Over the last few years in the UK, we have been subject to warm but very wet autumns and winters and this is providing the perfect growing conditions for mould and algae on artificial grass. 

At first glance, algae on artificial grass look like black patches or soil has been washed up to the surface, but in reality, it’s the beginnings of what can be a serious algae problem. 

Where artificial grass doesn’t drain quickly or there are overhanging trees, it’s possible for the ground to become more waterlogged after heavy rain. This allows algal spores to start to grow between the grass blades. Often by the time you see black patches on your artificial grass, you already have substantial algal growth at the base of the blades.

The algae grow at the bottom of the blades first, spreading sideways and blocking the drainage holes, meaning that it’s more difficult for water to drain from the surface and exacerbating the problem. Creating the perfect conditions for mould and algae to grow faster.

If you don’t address the problem of algae growth in your artificial grass it’s going to keep getting worse.

Black patches on artificial grassMoss growth is slightly different from algae growth. 

The best way to prevent moss or algae growth is to sweep, brush or rake your artificial grass weekly and to not allow litter to build up, so leaf litter and debris, to build upon the grass, especially where you have overhanging trees and branches and in areas where there’s not much sunlight reaching the grass.

If you are suffering from black patches on your artificial grass…

Don’t panic! This year, Top Dog Turf have launched Algae Traz a great new product to remove the black algae patches from your artificial grass with one quick and easy treatment!

Algae Traz is very easy to use.  Just spray & walk away! 

Brush or rake the leaves and debris off the lawn first.

Mix 50 ml of Algae Traz per 1 litre of water and spray it onto your lawn with a backpack sprayer, hand sprayer or a watering can with a fine rose end. 

No rinsing! 

Within 48 hours, the Algae Traz will start to kill the mould and the algae making it appear whiter and then over the next few weeks you’ll see that the algae disappear. 

The times of year that you need to treat the algae are the autumn, so September, October, and in the early spring, March or April, when the spores are growing.

Ideally, if you have artificial grass that is prone to algae growth, you would need to treat it twice a year, both autumn and spring to prevent the algae clogging the drainage holes and making your spring and summer dog wee deodorising difficult. 

Artificial Grass with AlgaeRemember! Never use harsh chemicals like bleach or acid-based cleaners on your synthetic turf, as this will damage the backing of the grass and make it more absorbent to dog urine. Bleach can run off the grass into the surrounding areas in the planting, which is always best avoided.

Algae Traz has been created by the grass experts at Top Dog Turf and is a quick and effective solution that will not damage your artificial grass or the surrounding areas. 

Just spray and walk away, no need for rinsing and watch the algae die off easily.

It’s safe for pets. We do recommend that you keep pets off the grass for several hours until the Algae Traz is dry. 

If they do get it on their paws, it’s no problem. Just rinse off and pat their feet dry just as a precaution. Although it shouldn’t cause any problems.

How to use Algae Traz to remove black patches of algae from your artificial grass. 

Top Dog Turf Mix 50 ml of Algae Traz per 1 litre of water into a garden sprayer or watering can. 

Top Dog Turf Brush or rake the grass upright, removing any loose debris, leaves or obvious moss using a medium-hard bristle brush or the brilliant Top Dog Turf Grass Groomer Rake.

Top Dog Turf Saturate your artificial grass with the diluted Algae Traz and then leave for several hours to dry. During that time, the Algae Traz will start killing off the algae and soaking into the grass to kill the algae at a deeper level. 

Top Dog Turf Make a cup of tea and sit down. That’s it. No need to rinse

The Algae Traz will sit on your grass and carry on working for several weeks or months to remove the mould and algae from your lawn. Leaving it looking lovely.



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  • David Glossop
    Posted at 13:13h, 10 November Reply

    Is it safe for pets to use after

    • topdogturfsupport
      Posted at 16:37h, 10 November Reply

      Hi David,
      We suggest that as you don’t rinse the Algae Traz off the grass, that you allow it to dry before you let your dogs back on it.
      At the correct maximum dilution of 50ml into each 1 litre of water it is safe, but we’d always err on the side of caution where paws are concerned!

      Emma 🙂

  • Kaubfa M
    Posted at 18:35h, 30 July Reply

    Your tips on preventing and treating algae with Algae Traz are helpful and practical. It’s crucial for artificial grass owners to avoid using harsh chemicals that could damage the grass and affect its durability. A consistent maintenance routine, along with the right products like Algae Traz, will ensure a beautiful and algae-free artificial lawn for years to come.

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