Why is My Driveway Green? How to Remove Algae & Moss

Updated February 2026 • 7 min read

If you've noticed your driveway, patio or path turning an unsightly shade of green, you're not alone. It's one of the most common problems homeowners face in the UK, especially here in Somerset where our damp climate creates perfect growing conditions. Let's explore why this happens and how to fix it.

What Causes Green Driveways?

That green coating on your driveway is usually one of three things:

1. Algae

Algae is the most common culprit. It's a simple plant-like organism that thrives in damp, shaded conditions. Algae creates that slippery green film you often see on driveways, especially in areas that don't get much sun. It can appear within weeks during wet weather and spreads rapidly.

2. Moss

Moss is a small, soft plant that grows in clumps or mats. Unlike algae, moss has a thicker, more textured appearance. It particularly loves growing in the joints between block paving and in cracks in concrete. Moss holds moisture against the surface, which can cause long-term damage.

3. Lichen

Lichen is a combination of algae and fungus living together. It appears as crusty, circular patches that can be green, grey, yellow or even orange. Lichen is tougher to remove than algae and can take years to develop.

Why Does My Driveway Get Green?

Several factors make your driveway prone to green growth:

• Shade – Trees, buildings or fences that block sunlight create perfect conditions for algae and moss
• Moisture – Poor drainage, overhanging gutters or areas that stay damp encourage growth
• Porous surfaces – Block paving, concrete and natural stone absorb moisture where organisms can thrive
• UK climate – Our mild, wet winters and humid summers are ideal for green growth
• Nearby trees – Falling leaves trap moisture and provide nutrients for algae and moss
• North-facing aspect – Surfaces that face north receive less direct sunlight

How to Remove Green From Your Driveway

Option 1: DIY Chemical Treatment

You can buy algae and moss killer from garden centres. These products typically contain benzalkonium chloride or similar biocides.

Pros:

• Relatively inexpensive (£15-£30 for concentrate)
• Easy to apply with a watering can or sprayer
• Kills spores to prevent regrowth

Cons:

• Takes 2-4 weeks to work fully
• Dead algae still needs removing (turns black/brown)
• Can harm plants if it runs off into borders
• Surface still looks dirty until pressure washed

Option 2: DIY Pressure Washing

Hiring a pressure washer and doing it yourself is a popular option.

Pros:

• Immediate visual results
• Hire costs around £50-£80 for a weekend

Cons:

• Risk of damaging the surface if pressure is too high
• Can dislodge sand from block paving joints
• Doesn't kill spores – growth returns faster
• Time-consuming and physically demanding
• Patchy results without proper technique

Option 3: Professional Pressure Washing (Recommended)

Professional cleaning combines the right pressure, proper technique and biocidal treatment.

What professionals do differently:

• Use surface cleaners for even, streak-free results
• Adjust pressure for different surface types
• Apply biocide treatments to kill spores at the root
• Re-sand block paving joints after cleaning
• Can apply sealant to prevent future growth

How to Prevent Green Driveways

Once your driveway is clean, here's how to keep it that way longer:

1. Improve drainage – Fix any areas where water pools or sits
2. Trim overhanging trees – More sunlight means less algae
3. Clear leaves regularly – Don't let debris accumulate
4. Fix gutters – Ensure water isn't dripping onto the driveway
5. Apply sealant – A quality sealant creates a barrier against moisture and growth
6. Annual maintenance – A yearly clean is easier and cheaper than a major restoration

Is Green Growth Dangerous?

Beyond looking unsightly, green driveways pose several problems:

• Slip hazard – Wet algae is extremely slippery, especially on slopes
• Surface damage – Moss roots can penetrate joints and cracks, causing structural damage over time
• Reduced property value – Kerb appeal matters when selling your home
• Harder to clean later – The longer you leave it, the more embedded it becomes

Summary

Green driveways are caused by algae, moss or lichen thriving in our damp UK climate. While DIY solutions exist, professional pressure washing with biocide treatment delivers the best, longest-lasting results. Regular maintenance and sealing can help keep your driveway looking clean for years.

If your driveway has turned green, don't worry – it's completely fixable. Contact Hulkzilla for a free quote and we'll have it looking like new.