Your Sandstone Cost Thousands. Don’t Ruin It With the Wrong Treatment.
Bleach stains it. Pressure washers pit it. Vinegar etches it. Our professional moss killer is specifically safe for natural stone – kills moss completely without risking your investment.
Indian sandstone is one of the most popular choices for patios and paths in the UK – and for good reason. Those warm, natural tones look stunning when the stone is clean. But there’s a problem: Indian sandstone is also a magnet for moss.
The porous nature that gives sandstone its beautiful character also makes it the perfect home for moss to take hold. And once it’s established, removing it without damaging your expensive patio becomes a real challenge.
Get it wrong and you could end up with etched, discoloured, or permanently damaged stone. Get it right and you’ll restore that beautiful natural finish you paid good money for.
Why Indian Sandstone Is So Prone to Moss
Understanding how moss spreads and reproduces helps explain why your sandstone patio seems to attract it more than other surfaces.
Indian sandstone is a sedimentary rock with a naturally porous structure. Under a microscope, the surface is covered in tiny holes and crevices – perfect anchor points for moss rhizoids to grip onto. Unlike smooth surfaces where moss can only sit on top, sandstone allows moss to embed itself deep into the stone structure.
This porosity also means sandstone retains moisture longer than non-porous materials. After rain, your sandstone patio stays damp for hours or even days, creating the consistently moist environment that moss thrives in.
Add in the typical British weather – plenty of rain, limited sunshine, and mild temperatures – and you’ve got perfect moss-growing conditions for most of the year.
What NOT to Do: Methods That Damage Sandstone
Before we cover what works, let’s talk about what doesn’t – because the wrong approach can cause permanent damage to your patio.
High-Pressure Washing
This is the most common mistake. Pressure washers feel satisfying to use and give instant results, but they’re terrible for Indian sandstone. The high-pressure water jet strips away the surface layer of the stone, leaving it pitted, rough, and more porous than before.
Worse still, that rougher surface actually attracts moss faster. You’ll notice regrowth within weeks, and each time you pressure wash, you’re removing more stone. Over a few years, you can significantly reduce the lifespan of your patio.
If you must use a pressure washer, keep it below 1200 PSI and maintain at least 30cm distance – but honestly, there are better methods.
Bleach and Chlorine Products
Bleach will kill moss, but it can also cause serious problems on natural stone. The chemicals can react with minerals in the sandstone, causing permanent discolouration – often an unpleasant orange or brown staining that’s impossible to remove.
Bleach also kills surrounding plants, damages soil health, and creates toxic runoff. It’s simply not worth the risk on expensive natural stone.
Wire Brushes and Aggressive Scrubbing
Scrubbing moss off with a wire brush might remove what’s on the surface, but it also scratches the stone and leaves visible marks. Those scratches create new anchor points for moss and trap dirt, making your patio look worse over time.
Vinegar and Acidic Solutions
While vinegar can kill surface moss, acidic solutions react with the calcium carbonate in sandstone. This causes etching – a dull, rough patch where the acid has dissolved the stone surface. On Indian sandstone, vinegar damage is often permanent.
The Right Way to Kill Moss on Indian Sandstone
Effective moss removal on Indian sandstone requires a two-stage approach: kill the moss first, then remove the dead material gently.
Step 1: Apply a Stone-Safe Moss Killer
The key is using a moss killer that’s specifically formulated to be safe on natural stone. These products penetrate the moss structure and kill it at the cellular level without reacting with the stone beneath.
Look for products that are pH-neutral or only mildly alkaline. Avoid anything acidic or heavily chlorinated. A professional-grade moss killer will state clearly whether it’s safe for natural stone – if it doesn’t mention stone safety, assume it isn’t.
Apply the moss killer according to the instructions, ensuring complete coverage of all affected areas. Timing matters – treat when moss is actively growing (spring or autumn) and when you have at least 24 hours of dry weather forecast.
Step 2: Wait for the Moss to Die
This is where patience comes in. Resist the urge to start scrubbing immediately. Give the product time to work – typically 7-14 days. You’ll see the moss change colour from green to yellow to brown as it dies.
Dead moss is far easier to remove than living moss because its grip on the stone weakens as it dries out.
Step 3: Remove Dead Moss Gently
Once the moss is completely dead, remove it using a stiff plastic brush (not wire) and water. Work in the direction of the stone grain and don’t apply excessive pressure. For stubborn patches, a second application of moss killer is safer than aggressive scrubbing.
A low-pressure rinse with a garden hose is fine – just avoid the jet setting or anything above 1000 PSI.
Preventing Moss from Coming Back
Killing moss is only half the battle. To keep your Indian sandstone looking good long-term, you need to address the conditions that encourage moss growth.
Improve drainage. If water pools on your patio, consider re-laying problem areas with better falls, or adding drainage channels. Standing water is moss’s best friend.
Reduce shade. Trim overhanging branches and shrubs to let more light reach the patio. Moss struggles in direct sunlight. Also check adjacent structures like rendered walls – moss can spread between surfaces.
Keep it clean. Sweep regularly to remove organic debris like leaves and dirt. This debris holds moisture and provides nutrients for moss.
Apply a sealant. A breathable stone sealant reduces porosity and makes the surface less hospitable to moss without trapping moisture inside the stone. Reapply every 2-3 years.
Treat preventatively. A light application of moss killer once or twice a year stops moss establishing before it becomes a visible problem.
Professional Treatment vs DIY
For small areas or light moss coverage, DIY treatment with the right products is perfectly achievable. However, if your patio has heavy moss coverage, existing damage, or you’re not confident about product selection, professional treatment might be worthwhile.
Professionals have access to commercial-grade products and equipment, and crucially, they have experience knowing how different stones respond to different treatments. A good professional will also spot potential drainage or structural issues that are contributing to your moss problem.
That said, prevention is always cheaper than cure. Regular maintenance with a quality moss killer keeps problems manageable and avoids the need for expensive professional restoration.
Frequently Asked Questions
Can I use a pressure washer on Indian sandstone at all?
Yes, but with extreme caution. Keep pressure below 1200 PSI, use a wide fan nozzle, maintain at least 30cm distance, and never concentrate on one spot. However, chemical treatment followed by gentle brushing is safer and often more effective.
How long does moss killer take to work on sandstone?
Most quality moss killers show visible results within 7-14 days. The moss will change from green to yellow/brown as it dies. Don’t try to remove it until it’s completely dead – rushing this stage can leave roots behind.
Will moss killer stain my Indian sandstone?
A proper stone-safe moss killer won’t stain. However, cheap or unsuitable products can cause discolouration. Always check the product is suitable for natural stone and test on an inconspicuous area first.
How often should I treat my sandstone patio for moss?
For prevention, treating once in spring and once in autumn is usually sufficient. If you’re dealing with an existing problem, you may need 2-3 treatments initially, then move to a maintenance schedule once the moss is under control.
Is moss on Indian sandstone just a cosmetic problem?
No – moss holds moisture against the stone surface, which can accelerate weathering and cause the stone to flake or crack over time, especially through freeze-thaw cycles in winter. It’s also a slip hazard when wet. Treating moss protects both the appearance and structural integrity of your patio.
Ready to restore your sandstone patio? View our professional moss killer – safe for natural stone and proven to deliver lasting results.
