Our Product
We make a moss, mould and algae killer for hard surfaces. It works well and we stand behind it. But this article is about helping you find what’s right for your situation, even if that’s not us.
Search for “best moss killer UK” and you’ll find dozens of articles recommending products. Most are affiliate link farms dressed up as reviews. The recommendations change based on which products pay the highest commission.
This guide is different. We actually sell a moss killer, so we have no affiliate relationships with competitors. Instead, we’ll explain what actually works, why most products contain the same active ingredients, and help you choose based on your specific situation.
The Truth Most Articles Won’t Tell You
Here’s what the moss killer industry doesn’t want you to know: most products for hard surfaces contain the same active ingredient. It’s called benzalkonium chloride, a quaternary ammonium compound that kills moss, algae, and lichen on contact.
Wet and Forget, Patio Magic, SmartSeal, Jarder Spray and Leave, and dozens of other brands all use variations of this ingredient. The main differences are concentration, dilution ratios, and price.
This isn’t a criticism. Benzalkonium chloride works well. But understanding this helps you make smarter choices instead of paying premium prices for fancy marketing.
The exception is lawn moss killers, which typically use iron sulphate instead. More on that shortly.
Matching Products to Your Situation
The “best” moss killer depends entirely on what you’re treating and your circumstances. Here’s how to choose:
For patios, driveways, paths, and walls: Any benzalkonium chloride product will work. Choose based on price, concentration, and convenience. The spray-and-leave products are easiest. Concentrates offer better value for larger areas.
For lawns: Iron sulphate is the traditional choice. It kills moss and feeds grass simultaneously. But it permanently stains hard surfaces, so keep it away from patios and paths.
For gardens with pets, children, or ponds: Natural products like MossOff use oils and starches instead of chemicals. They’re slower but completely safe once dry.
For large areas on a budget: Concentrated products or professional-grade benzalkonium chloride (sold as BAC 50) offer the best value per square metre.
For convenience: Ready-to-use spray bottles cost more per application but require no mixing.
Products Worth Considering
Rather than declaring one product “the best,” here are solid options for different needs:
Patio Magic is widely available at B&Q, Wickes, and supermarkets. Around £20 for 5 litres of concentrate. Works in 2-4 days on most growth. A reliable choice that’s easy to find.
Wet and Forget is popular and well-reviewed, though typically more expensive than similar products. Works gradually over days to weeks. Good coverage and genuinely effective.
SmartSeal is favoured by professionals for stubborn growth on roofs and heavy moss. Slightly more aggressive formulation that works faster on tough cases.
Pro-Kleen Iron Sulphate is excellent for lawn moss. Very affordable and doubles as a lawn tonic. But keep it strictly on grass as it causes permanent orange staining on hard surfaces.
MossOff is the best natural option for pet owners concerned about chemicals. Made from oils and starches. Takes longer but leaves no residue and won’t harm animals or plants.
Our product sits in the mid-range for hard surface treatments. We formulated it to work quickly without damaging surfaces, and we provide clear guidance on how to use it properly.
The Iron Sulphate Warning
This deserves its own section because so many people get caught out.
Iron sulphate is brilliant for lawns. It kills moss, feeds grass, and improves lawn colour. Greenkeepers have used it for decades.
But iron oxidises (rusts) when it dries. If iron sulphate touches your patio, driveway, render, or any hard surface, it leaves bright orange stains that are almost impossible to remove. These stains can persist for years.
Even careful application often results in some staining around lawn edges from spray drift or runoff. If your lawn borders a patio, consider using a different product near the edges, or accept that some staining may occur.
Never use iron sulphate on hard surfaces. For patios, concrete, block paving, and walls, use benzalkonium chloride products instead.
If You Have Pets or Children
Most moss killers are safe once dry. The key word is “once dry.” During application and while the product is wet, keep pets and children off the treated area.
Benzalkonium chloride products typically need a few hours to dry. Iron sulphate can take longer, especially in damp conditions. Natural products like MossOff are safe immediately after drying.
If you have pets that graze the lawn (rabbits, guinea pigs, chickens), be more cautious. Keep them off treated areas for at least two weeks, or use a natural product designed for grazing animals.
For gardens with ponds, be aware that most moss killers are toxic to aquatic life. Avoid application near water and don’t let runoff enter ponds or water features.
What Nobody Tells You About Results
Here’s what the marketing rarely mentions:
Dead moss doesn’t disappear. Moss killers kill moss. They don’t dissolve it or make it vanish. Once dead, the moss still sits there until you remove it manually or let weather gradually break it down. Pressure washing or brushing is usually needed to clear dead growth.
No product prevents regrowth forever. Expect 6-12 months before moss returns, depending on conditions. Shaded, damp areas regrow faster. Preventative reapplication in spring and autumn extends protection.
Speed varies with conditions. Products work faster in warm, dry weather. Cold or wet conditions slow everything down. That “kills in 24 hours” claim assumes ideal conditions.
Stubborn black lichen takes longer. Green algae dies quickly. Thick moss takes a week or two. Black lichen can take months to fully break down, even after treatment. Patience is required.
Prevention Beats Cure
The best long-term strategy is making conditions less favourable for moss:
Improve light levels by trimming overhanging vegetation. More sunlight means faster drying after rain.
Address drainage issues. Standing water and permanently damp surfaces are moss magnets.
Keep surfaces clean. Regular sweeping removes organic matter that moss feeds on.
Apply preventative treatment. A light application twice a year stops moss establishing before it becomes visible.
Understanding why moss keeps returning helps you address root causes rather than repeatedly treating symptoms.
Getting the Best Results
Whichever product you choose, these principles improve results:
Apply to dry surfaces. Most products need the surface dry during application. Check the weather forecast and avoid treating before rain.
Treat before you clean. Apply moss killer first, wait for it to work, then remove the dead moss. Removing live moss first just spreads spores around.
Be thorough. Missed patches regrow quickly. Ensure complete coverage of affected areas.
Give it time. Don’t scrub or pressure wash immediately after treatment. Let the product work for at least a week before removing dead growth.
Consider the surface. Soft stone, old brick, and delicate surfaces may need gentler treatment. Test on an inconspicuous area first.
Our moss, mould and algae removal guide covers the complete treatment process for different surfaces.
The Bottom Line
There’s no single “best” moss killer. The right choice depends on what you’re treating, whether you have pets or children, your budget, and how much effort you want to invest.
For most people treating hard surfaces, any reputable benzalkonium chloride product will work. Choose based on availability and price rather than marketing claims.
For lawns, iron sulphate remains the professional choice, but requires care around hard surfaces.
For maximum safety, natural products offer peace of mind at the cost of slower results.
Whatever you choose, remember that treatment is only part of the solution. Understanding how moss killers work and addressing the conditions that favour moss growth will give you better long-term results than any product alone.
Our product works well on hard surfaces and we’re confident enough to let you compare it fairly against alternatives. If it’s right for your situation, great. If something else suits you better, we hope this guide helped you find it. See our Moss, Mould & Algae Killer
