Some things you just have to see to believe. A concrete patio covered in algae and mildew is one of them — not because the buildup is surprising, but because of what happens when it’s gone.
This is the story of a recent job we did here in the Central Valley. A patio that had been slowly taken over by green and black growth, and what it looked like when we were done.
How Does a Concrete Patio Get This Bad?
It happens gradually, which is part of why it catches homeowners off guard. Concrete is porous, which means it doesn’t just collect surface dirt — it absorbs moisture. And anywhere moisture sits, algae and mildew follow.
Patios are especially vulnerable. They’re low to the ground, often shaded by fences, overhangs, or trees, and don’t get the kind of airflow that dries things out quickly. In the Central Valley, the combination of winter moisture and warm temperatures creates ideal conditions for organic growth to take hold and spread.
What starts as a faint green tint in one corner can work its way across an entire patio surface over a season or two. By the time most homeowners notice it, it’s been building for a while.
And beyond the way it looks, algae and mildew on concrete can actually make the surface slippery — especially when wet. A patio that’s become a hazard underfoot is a problem that goes beyond curb appeal.
Why a Garden Hose or DIY Pressure Washer Won’t Cut It
This is where a lot of homeowners get stuck. They rent a pressure washer, spend an afternoon on the patio, and end up with results that are underwhelming at best — streaky, uneven, and back to looking the same way within a few months.
The issue is that pressure alone doesn’t kill algae or mildew. It can blast the surface growth off, but the root structure stays behind in the pores of the concrete. Without treating that, the growth comes back faster than it appeared the first time because it already has a foothold.
Professional concrete cleaning uses the right combination of cleaning solution and pressure to treat the surface, break down the organic growth at the root, and rinse it away cleanly. The result isn’t just cleaner-looking concrete — it’s concrete that stays cleaner longer because the source of the problem has actually been addressed.
The Job
When we arrived, the patio was covered in heavy algae and mildew buildup. The kind that makes the whole outdoor space feel dark and neglected, even on a bright day. The concrete underneath was in good shape — it just hadn’t been seen in a while.
We treated the surface, let the cleaning solution do its work, and pressure washed the patio clean. The transformation was the kind that makes the job satisfying — concrete that went from green and grimy to bright and clean, looking the way it did when it was new.
The homeowner didn’t need a new patio. They just needed the right clean.
What to Do If Your Patio Looks Like This
If your concrete patio has algae, mildew, or green staining, it’s very likely cleanable. Most concrete that looks worn down or neglected looks completely different after a professional cleaning — and the process is faster than most people expect.
A few signs it’s time to schedule a concrete cleaning:
- Green or black growth across the surface
- Slippery spots when the patio is wet
- Concrete that looks dark or stained even after rain
- Growth returning quickly after a DIY clean
- The patio just doesn’t look the way it used to
The longer organic growth sits on concrete, the more embedded it becomes. Staying ahead of it with routine cleaning is always easier than playing catch-up.
Keep It Clean Year-Round
If you want to make sure your patio never gets to that point again, our recurring service plans have you covered. The Premium Bundle includes concrete cleaning as part of a full exterior maintenance schedule — house washing, window cleaning, gutter cleaning, and concrete cleaning, available twice a year or quarterly.
It’s the easiest way to make sure your outdoor spaces stay looking their best without having to think about it.
Ready to See What Your Patio Could Look Like?
If your concrete patio, driveway, or walkway has seen better days, we’d love to show you what a professional clean can do.
Contact Delta Softwash today to schedule your concrete cleaning. We serve homeowners throughout the Central Valley including Stockton, Lodi, Elk Grove, Sacramento, Folsom, Manteca, Tracy, and surrounding communities.