March 8th, 2022 by Sarah Miles

What you need to know about black lichen

The black, ink spatter-like spots on your patio, drive, or paths are not dirt but a living organism that cannot simply be cleaned away. Here’s what you need to know about this persistent blight on your outdoor hard surfaces.

It’s been growing for a lot longer than you think

Black lichen, which is the correct name for the black spots, starts life as microspores from trees and plants which get carried on the wind and settle on hard surfaces. They are not usually visible to the human eye for up to four years before the spots appear. By which time, they have become established.

It’s sapping minerals from your stonework

Lichen is parasitic because it feeds on the minerals found in stone and concrete. It will feed in an area and once it has exhausted the supply there, it spreads out seeking more.

There is more going on than you can see

Lichen feeds by sending tendrils called hyphae down into the stone. These grow at a rate of around 2mm per year. This doesn’t sound like a lot but remembers it grows for a number of years before you even see it and it’s enough to form a really strong grip on the stone.

It also forms a crust on the surface

As well as burrowing deep into the stone, it also forms a hard crust over the visible surface. This makes it resistant to general household cleaning products and abrasive tools such as brushes.

You can’t scrub it away, but you could damage the stone

These two defence mechanisms – the tendrils and the hard crust – make it impossible to clean away with standard methods but if you try, you can easily end up damaging the stone itself which is counter-productive.

It can be removed though

The good news is that it can be removed. The great news is that it requires very little effort and zero manual labour. It’s just about using the right product. This job requires an issue-specific product with an active ingredient, which in this case is Sodium Hypochlorite. Specialist black spot remover is formulated to break the organisms’ bond with the stone, allowing it to be rinsed away.

Apply, leave, rinse

Getting rid of black spot is this simple:

1. Apply: apply neat to the surface using a sprayer or watering can
2. Leave: just walk away and leave it to work for 2-4 hours, or even overnight. Keep animals and children away during this time
3. Rinse: once it has performed its magic, simply rinse with clean water, taking the black spots with it. Once dry it’s safe to use again

It cleans general dirt too

Drives, patios, and paths will also attract other environmental materials – dirt, mould, algae etc. The good news is that a black spot remover will also clean these contaminants away too so a simple treatment deals with everything and your hard surfaces will look like new again.  

Ultima Plus XP Ultimate Black Spot Eliminator 5L

Price: £29.95

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