Rainy season brings freshness to the environment, but it also creates perfect conditions for unwanted plants, algae, moss, and grasses to grow on your outer walls. These green invaders don’t just ruin your home’s appearance — they also cause long-term structural damage if ignored. This blog will help you understand how to remove grasses and algae from your outer home walls, why they appear during monsoon, and how to prevent their regrowth effectively.
Why Do Grasses and Algae Grow on Outer Walls?
During the rainy season, constant moisture, damp surfaces, and shaded areas promote the growth of algae, moss, and grasses. Cracks in plaster, water seepage, and poor drainage allow tiny plant seeds and spores to settle and grow. Sunlight rarely reaches such areas, and the combination of dirt and water offers the perfect base for plant life to take root.
Common Signs of Grasses and Algae on Walls
- Greenish, slimy patches (algae)
- Tiny grass blades poking out of cracks
- Mossy textures, especially in corners or on tiled surfaces
- Paint discolouration or blistering
- Wet and damp feel on wall surfaces
Why You Should Remove Grasses and Algae Immediately?
- Weakens Structure: The roots of small grasses can deepen wall cracks, letting in more moisture, which in turn weakens bricks and plaster.
- Spoils Wall Paint: Damp walls cause paint to peel off, bubble, or fade over time.
- Promotes Mould Growth: Where there is algae, mould usually follows — this can affect your family’s health.
- Poor Curb Appeal: Green streaks and weeds growing on outer walls can make even a well-maintained home look neglected.
Home Remedies to Remove unwanted plants and grasses from walls
These natural solutions are safe, affordable, and eco-friendly:
1. Vinegar Spray
Mix 1 part white vinegar with 3 parts water in a spray bottle.
Spray directly on algae patches and wait 30–40 minutes.
Scrub with a brush and rinse.
2. Salt and Boiling Water
Pour boiling saltwater on small grass growths to kill the roots.
Be cautious: avoid run-off to nearby garden areas.
3. Baking Soda Paste
Make a thick paste of baking soda and water.
Apply to affected areas and leave for an hour before scrubbing.
4. Lemon Juice
Naturally acidic, lemon juice can dissolve light algae build-up.
Best for small or early-stage patches.
5. Clove or Tea Tree Oil
Add a few drops to water and spray on mossy or fungal areas.
Let sit before wiping or rinsing.
Chemical Products from the Market to remove unwanted plants and grasses from walls
For tougher or recurring problems, chemical-based solutions offer fast and lasting results.
1. Sodium Hypochlorite (Liquid Bleach)
Common in most household bleaches.
Mix 1 part bleach with 10 parts water and spray on walls.
Kills algae spores and disinfects the surface.
2. Algae and Fungal Removers
Brands like Dr. Fixit Bioclean, Berger Bio-Wash, and Asian Paints Bio-Shield are specifically made to clean exterior walls.
Apply with a brush or roller and allow contact time as per instructions.
3. Pressure Washer Cleaners
Solutions like Karcher Algae Remover or Bosch Wall Wash can be added to pressure washers for deeper cleaning.
4. Waterproofing Sealants with Anti-Algal Agents
After cleaning, applying products like Dr. Fixit Raincoat or Pidilite Dampguard can prevent future growth.
Safety Tip: Always wear gloves, eye protection, and a mask while using chemical-based products.
Step-by-Step: How to Remove Grasses and Algae from Walls
1. Initial Cleaning
Start with a dry scrub using a wire brush to loosen algae or remove grasses. Focus on wall joints, tile edges, and wall base areas.
2. Manual Grass Removal
- Use a putty knife or scraper to dig out grasses growing in cracks.
- For deeper growth, insert a small screwdriver to remove the roots.
- Avoid pulling with your hands as the roots may remain and regrow.
3. Use a Natural Cleaning Solution
Make a DIY cleaner using:
- Vinegar (1 part) + Water (3 parts): Spray generously on the algae or moss.
- Let it sit for 30–40 minutes, then scrub with a hard-bristled brush.
- Rinse the wall thoroughly with clean water.
4. Chemical Treatment (For Severe Growth)
Use a commercial anti-algae or anti-fungal wall cleaner, which contains biocides that kill spores and prevent regrowth. Make sure the surface is rinsed well after application.
Tip: Use gloves and protective eyewear while using strong cleaners.
5. Pressure Washing
If the wall surface is tiled or concrete-based, you can use a pressure washer to remove algae stains and plant residue. Avoid pressure washing painted surfaces as it can strip paint.
Prevention: Stop Grasses and Algae Before They Start
1. Seal All Cracks
Use exterior wall putty or silicone sealant to fill all gaps and cracks — especially where grasses were growing earlier.
2. Use Anti-Fungal Exterior Paint
High-quality exterior paints now come with anti-algal properties. Repainting with such paints can prevent regrowth for years.
3. Improve Drainage
Ensure proper slope around your house to prevent water stagnation. Rainwater should flow away from the walls, not towards them.
4. Trim Vegetation Nearby
Plants and shrubs growing too close to your wall can trap moisture and shade the wall, encouraging algae. Keep them trimmed.
5. Apply Water Repellent
Apply a silicone-based wall water repellent to block moisture from entering the surface and feeding algae or grasses.
Eco-Friendly Grass and Algae Removal Ideas
- Boiling Water: Pour over small grass tufts to kill the roots instantly.
- Baking Soda Paste: Apply on algae and let it sit overnight before rinsing.
- Lemon Juice: Natural acid that works well on early-stage algae.
Long-Term Maintenance Tips
- Check walls monthly during rainy season.
- Clean damp patches as soon as you notice them.
- Repaint every 4–5 years with anti-fungal paint.
- Ensure ventilation indoors to reduce internal dampness that affects outer walls.
Conclusion
The rainy season may be unavoidable, but the problems it brings — like grasses and algae on home walls — can be controlled with timely care. By understanding the causes, applying the right cleaning techniques, and following regular preventive maintenance, your home walls can stay clean, dry, and beautiful throughout the year. Don’t let nature take over your structure — take control with smart upkeep.
FAQs
Q1: Why do grasses grow on concrete or plastered walls?
Grasses can grow in cracks where soil or dust has settled. If a seed finds moisture, it can germinate even on concrete walls.
Q2: Are all algae harmful to walls?
While algae are not structurally harmful in small amounts, over time they retain moisture, attract insects, and promote deeper problems like mould and damp.
Q3: What is the best time to remove grasses and algae?
Start as early as the monsoon begins. Don’t wait for the growth to become severe. Early action prevents deeper root penetration and paint damage.
Q4: Can I repaint over algae-infected walls?
No. You must first clean and disinfect the wall surface before applying primer and paint. Painting over algae leads to paint peeling and staining.
Q5: Will pressure washing damage my walls?
Not if done correctly. Use moderate pressure on hard surfaces like stone or tiles. Avoid using high pressure on painted or plastered surfaces.