Why Your San Diego Driveway Turns Green in Summer (and How to Get Rid of It for Good)
You cleaned the driveway a few months ago, and the green film is already creeping back along the edges and in the shaded sections. It's frustrating, it's slippery, and it makes an otherwise sharp property look neglected. Here's what's actually going on — and why the usual approach doesn't keep it gone.
That green isn't dirt — it's alive
The green tint on concrete is algae, and it's a living colony, not surface grime. It thrives on three things San Diego serves up in abundance: moisture, shade, and time. Marine layer rolls in overnight and keeps concrete damp well into the morning. Anywhere the sun doesn't fully dry the surface — the north side of the house, under trees, along a fence line, the low spot that holds water — algae takes hold and spreads. Summer doesn't stop it; the humidity and morning fog of the coastal months actually feed it.
Why it's more than an eyesore
Algae on a driveway or walkway is genuinely slick when it's damp — a real slip hazard on entry paths, pool decks, and steps. Left long enough, the organic growth also works into the pores of the concrete and holds moisture there, which accelerates surface breakdown and staining. And on a premium property, a green-streaked driveway quietly undercuts everything else you maintain. It's usually the first thing a visitor's eye lands on.
Why it keeps coming back
Most people rent a pressure washer, blast the surface, and call it done. The driveway looks better for a few weeks — then the green returns. The reason is simple: a plain water blast removes what's on the surface but doesn't kill the algae rooted in the concrete's pores, so the colony regrows from what's left behind. You also risk etching or "striping" the slab with an inconsistent wand technique, which leaves permanent wand marks across the concrete.
How we actually get rid of it
The fix is a two-part approach: a cleaning solution that kills the algae at the root, followed by professional pressure washing at the correct pressure for the surface, using a surface cleaner that leaves an even, stripe-free finish. Killing the growth first is what makes the result last — you're not just moving the algae around, you're removing what it grows back from. On surfaces that can't take high pressure, like some stamped or older concrete, we drop to a soft-wash approach so the slab gets clean without getting damaged.
We handle driveways, walkways, patios, pool decks, and pavers across San Diego County — from the coastal homes in Del Mar and La Jolla to the larger lots inland in Poway and Rancho Santa Fe, where longer driveways and extensive hardscape collect the most buildup.
How often does it need doing?
Most San Diego driveways do well with a cleaning once a year to stay ahead of algae and oil buildup. Heavily shaded properties, or homes surrounded by trees, may want it more often. The best time is before the growth gets thick — a light annual clean is far cheaper and faster than reversing years of embedded staining.
Ready to get rid of the green for good?
If your driveway, patio, or walkway is going green anywhere in San Diego, we can take care of it — and do it in a way that actually stays gone. Get a free quote for pressure washing at toptierexteriorservice.com or call (619) 890-8888.
