How do I remove black spot from my patio?

If your patio has developed black marks which you are struggling to remove, the probability is that your patio is suffering from Black Spot.

If you have these tell-tale marks on your paving, you’ve got black spot

See it here on a recent customer’s sandstone patio:

 

And here on a granite patio last year:

Read this blog to understand what Black Spot is , and the best way to remove it:

What is Black Spot?

Black Spot is lichen which thrives on stone surfaces in the damp and shady conditions that are so common in the UK. The characteristics of the lichen are that as it matures, it sends out tendrils (hyphae) into the pores of the stone seeking nutrients from the minerals in the stone and the detritus that collects on the patio. These gradually spread through the surface of the affected stone.

Therefore it is a bigger problem on stones that have larger pores as part of its structure.

Black Spot does not generally occur on Indian limestone because the structure of the stone is very close grained and there is no opportunity for detritus to collect on the surface. Typical Indian Limestones that would be in this group are Kota Brown, Kota Blue, Black Limestone & Tundra Limestone.

Sandstone has a much more open texture with larger pores and is therefore much more likely to be affected by Black Spot.

However, there is a hierarchy within the Indian Sandstones, whereby some colours are more affected than others.

For instance, the better quality Raj Green is one of the densest, close textured sandstones available, and therefore, because of its structure, will not be affected.

However, as you move through the colour range of the Indian Sandstones from dark to light, the occurrence of Black Spot becomes more prevalent:

Black Sandstone   Slightly Affected

Kandla Grey

Modak

Mellow Yellow

Fossil Mint            Highly Affected

Fossil Mint, one of the most popular Indian Sandstones, has the lightest colour, & the largest pores, so it is the stone surface that is going to have the worst incidence of Black Spot, particularly if the stone is laid in damp, shady conditions with lots of surrounding plant growth.

Will pressure washing remove black spot from my patio?

During the first 2 years after a stone surface has been laid, any Black Spot growth will appear to be simply a surface problem that can be successfully removed by power washing, however this is not removing or killing the spreading hyphae that are within the stone surface.

Over an extended period the hyphae, now well established within the stone surface creates an anchor for the black spot to colonise the stone surface which will become increasingly blackened, and more difficult to clean away.

If pressure washing is not effective, what other options are there for removing black spot from my patio?

The use of a high temperature, low pressure steam cleaner (such as Doff) will kill the black spot but won’t always remove the more stubborn black marks on the stone unfortunately (dead but not removed!)

What is the most effective way of removing Black Spot from my patio?

A far more effective way of killing and removing black spot, is to use a product like Rob Parkers Best Patio Cleaner, which has been developed by scientists after researching the best way to kill the lichen to prevent new growth, and also remove the existing marks.

Rob Parkers Best is a biocide which will get into the growth & kill the Black Spot permanently, but also has a bleaching agent which will bleach the blackness out of the visible Black Spot.

To work properly it is necessary to ensure that the Rob Parkers Best Patio Cleaner remains on the affected stone for at least an hour, and that during the treatment period the stone surface remains wet.

After treatment the biocide will have killed all the Black Spot spores, preventing new growth from occurring in the future, plus most of the remaining dead black spot deposits will not be visible as the chlorine content will have bleached them.

Sometimes, particularly stubborn deposits will remain on the stone after treatment.

Rest assured, that over time, now that there is no live lichen in the stone, these (bleached) dead deposits will loosen, and the next time the patio is power washed, any remaining lichen deposits will be removed and the stone surface will become as clean and brilliant as it was when first laid.

Buy Rob Parkers Best Patio Cleaner here today>>

15 thoughts on “How do I remove black spot from my patio?

  • 27th February 2019 at 7:09 am
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    Is your black spot patio cleaner safe to use near plants? Thankyou.

    Reply
    • 5th March 2019 at 11:52 am
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      Hi,

      Thank you for your email. We do not recommend that Rob Parkers Best Patio Cleaner comes into contact with plants.
      Thank you

      Reply
      • 10th April 2020 at 9:59 am
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        Hi, I have black spot on a sandstone courtyard and am looking for the right product to deal with it. The drainage is into establish planting and I want to try to protect the plants. Will your product effect the plants?

        Reply
        • 14th April 2020 at 3:23 pm
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          Hi

          We would not recommend that this product is allowed to drain into the planted area, as it may cause damage to the plants

          Reply
  • 10th April 2020 at 10:50 am
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    What is the active ingredient please ?

    Reply
  • 26th April 2020 at 3:14 pm
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    Is black spot remover safe to use with pets once dry?

    Reply
    • 28th April 2020 at 4:48 pm
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      Hi
      whilst you are treating the affected area with Patio Cleaner, the surface must remain wet to activate. During this treatment keep pets away from the area. When rinsed away the patio will be clean and the area will be safe for pets to use. The product should not be allowed to dry and remain on the stone.

      Reply
  • 16th June 2020 at 8:33 am
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    Is this treatment safe to use if you have dogs

    Reply
    • 18th June 2020 at 10:58 am
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      Please keep pets away from the area whilst it is being treated.

      Reply
  • 5th July 2020 at 8:06 am
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    where can I buy the black spot remover? I am in dublin

    Reply
    • 29th July 2020 at 3:16 pm
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      Hi, we are sorry but as yet we don’t ship to Eire. We need a distributor!

      Reply
  • 28th July 2020 at 6:14 am
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    Hi, thank you for such a brilliant post. I have been reading some blogs that gives me more knowledge about how do I remove black spot from my patio; I must say this is one of the best among them. You have done a great research for I feel, thanks for sharing.

    Reply
  • 19th September 2020 at 10:22 pm
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    Hi there.
    When you say keep wet do I just watch over the patio area for the hours treatment and top up with a quick spray of the hose? I don’t want to dilute your product etc.

    Reply
    • 24th September 2020 at 10:24 am
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      Try to avoid evaporation of product by covering the treated area with thin plastic. If drying out does occur retreatment will be required for best effectiveness.

      Reply

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