Last Updated on October 20, 2026 by Umar Farooq
Lichen on pavers is a flat, crusty growth, often black, grey, yellow or orange, that is a partnership between an alga and a fungus, and the fungus is what holds on. It is stubborn because it is attached, not just sitting on top. Soft brushing and a hose are the first thing to try, diluted bleach is the usual second step, and abrasives and hard pressure are the ones to avoid. Expect to repeat the treatment and to fix whatever keeps the surface damp.
The Paving Expert, a UK paving guide, says the black or sometimes white spots on paving are almost always lichen. It is the clearest description I found, and I cross-checked it against two other guides. (The site is British, so some products it names are not sold in the US.)
Lichen, moss or algae?
The three behave differently, which changes the fix. According to Dynamic Stone Tools' guide:
| Growth | Looks like | How it holds on | Gentlest removal |
|---|---|---|---|
| Algae | Thin film, green or black | Sits on the surface; least physically damaging | Soft brush and wash |
| Moss | Soft cushion that holds water | Rootlike rhizoids in surface pores | Brush, then treat |
| Lichen | Flat crusty discs or leafy rosettes | Fungal structures penetrate shallowly into the stone | Biocidal wash first, brush after |
If it is soft and fluffy, see how to clean moss off pavers. If it is flat, crusty and will not wipe off, it is lichen.
Is lichen harmful to pavers?
The guides I opened do not call it structural. Kennards, an Australian hire company, says algae, moss and lichen make surfaces slippery, which is a hazard, especially in cool or wet periods. The Paving Expert says the fungus sends rootlets into the paving, which is why it is hard to remove. It also says some materials are more prone than others: sandstone is the most vulnerable because it is porous, limestone less so, granite and basalt more resistant, and low-cement wet-cast concrete products are more prone than cement-rich pressed pavers.
I could not find a study on how fast lichen damages concrete pavers, so I will not give you a number. The honest summary: it is mostly a looks-and-slip problem, and it points to a surface that stays damp.
The removal ladder, gentlest first
- Test first. Pick a hidden corner. The Paving Expert says to avoid abrasives such as wire brushes and grinders, which can permanently damage paving. Kennards suggests a plastic scraper for stubborn spots on flat pavers, and a wire-bristle brush for dry material. Those two disagree on wire. I would follow the first and stay with nylon or plastic.
- Soft brush and hose. Dynamic Stone Tools recommends a firm hose spray and a good brush for soft stone.
- Diluted bleach, on the whole surface. The Paving Expert says to start at 10:1 (water to bleach, as I read it) and move toward 1:1 only if necessary, never neat. Treat all of the paving, not just the lichen, to avoid clean patches. Wet the surface first, rinse afterwards, and do not let it dry on. Kennards gives one cup of bleach to four litres of water, which works out to roughly 1 part bleach to 16 (my arithmetic). Test it first, as it may discolor some stones. Bleach on pavers has our dilution table and plant protection tips.
- Repeat. The Paving Expert says stubborn growth may need three or more treatments with a day or two between them.
Let the treatment do the work
Dynamic Stone Tools says lichen needs a different sequence from moss. Apply a biocidal wash first, wait for the discs to brown and loosen, then brush gently. It lists scraping live colonies as a practice to avoid. Wet & Forget describes a one-customer result: a diluted spray left for several weeks, with no scrubbing. That page is promotional, so treat it as a product claim, not evidence. If you try a commercial product, follow its label.
On pavers with sealer, bleach can strip or degrade it, as covered in the bleach article.
Pressure washing: only on tough stone
Dynamic Stone Tools says a moderate fan pattern at a shallow angle can work on dense granite and quartzite pavers with sound joints. On soft, porous or weathered stone it can erode the surface and strip joint material. Their fingernail test is useful: press a nail into a hidden corner, and if grains scratch or dislodge easily, do not pressure wash. Our power washing pavers guide covers tip and distance.
Why it comes back, and how to slow it
Lichen needs moisture and stable conditions. Kennards recommends improving drainage so rainwater runs off or evaporates, avoiding shaded spots, and pruning overhanging plants so stones dry faster. The Paving Expert adds that regular biocidal washes can deter it, and that a sealant which stays intact can block lichen from the surface, while debris on top gives it a place to start. I would not seal only to stop lichen: sealing is something you do when there is a reason, not on a schedule, and the wrong sealer on the wrong paver creates its own problems. Our paver cleaning guide covers the broader routine.
Brush it, bleach it weakly and dry the spot out
For lichen on pavers: test a corner, use a soft brush and hose, move to a weak bleach mix on the whole surface, repeat as needed, and fix the shade or drainage that let it settle. Do not reach for the wire brush. The lichen has been there longer than your patience, and it will still be there if you scar the stone doing it fast.
FAQ
What is the black spotting on my pavers?
Often lichen. The Paving Expert says black or sometimes white spots on paving are almost always lichen, a partnership between an alga and a fungus.
How do I remove lichen from pavers?
Start with a soft brush and hose, then a diluted bleach solution on the whole surface, rinsing afterward. Stubborn growth can take three or more treatments, with a day or two between them.
Does vinegar kill lichen on pavers?
Kennards suggests undiluted 5 percent white vinegar scrubbed on with a soft brush, repeated if needed. Other sources lean on bleach or commercial biocides, and acid can harm some stones, so test first.
Can I pressure wash lichen off pavers?
Only on dense stone such as granite with sound joints, with a wide tip and low pressure. On soft or weathered stone it can erode the surface and strip joint sand.
How do I stop lichen coming back?
Reduce moisture and shade: improve drainage, prune overhanging plants and keep debris off the surface. Periodic biocidal washes can also help.
