The short answer: more often than you think, and more often than the same house would need almost anywhere else in the country.
Miami-Dade and Broward average over 60 inches of rain a year. Add year-round heat, humidity that never really breaks, and salt in the air near the coast, and you get close to ideal growing conditions for algae, mold, and mildew. They don't take a season off here. A driveway in Ohio might go three years between cleanings. The same driveway in Kendall starts going green in five months.
By Surface Type
Driveways & walkways - every 6 to 12 months. Concrete is porous, so organic growth gets a foothold fast. If your driveway is shaded, sits under a tree line, or stays damp after rain, plan on the shorter end. Full sun and good drainage buys you closer to a year.
Roofs - every 1 to 2 years, soft wash only. Those dark streaks aren't dirt. They're a living organism, and they spread. See our guide on roof streaks for what's actually growing up there and why pressure is the wrong tool.
House exterior - once a year, twice if you're near the water. Salt air accelerates buildup on stucco and painted surfaces. Anything within a few miles of the coast should be on a six-month rhythm.
Pool decks & patios - every 6 to 12 months. These get the worst combination in South Florida: foot traffic, splash-out from the pool, and shade from screen enclosures. Algae loves all three. Travertine and natural stone also stain more readily than concrete, so letting it go is more expensive to fix later.
Fences - every 12 months. Wood and vinyl both go green on the shaded side long before the sunny side shows anything. Check the north-facing panels.
How to Tell You're Overdue
You don't need a calendar. The surface tells you:
A green or gray tint across concrete that looks like discoloration rather than dirt. Black spots on a roof or fence that don't rinse off with a hose. Surfaces that stay slippery when wet - that's biological growth, and it's a genuine fall risk on pool decks and entry walkways. Dark streaking under gutters and soffits where water runs consistently.
If you're seeing any of those, you're past due rather than approaching it.
Waiting Costs More Than Cleaning
Organic growth isn't only cosmetic. It holds moisture against the surface it's living on. On a roof, that shortens the life of the material. On wood, it accelerates rot. On concrete and pavers, deep-set staining becomes progressively harder to lift - a driveway cleaned every eight months comes back to near-original color, while one left for four years often won't fully recover no matter what you do to it.
The other cost is the letter from your HOA. Most Miami-Dade associations expect visible cleanliness year-round, and enforcement is usually complaint-driven - meaning you find out you're behind when a neighbor reports you. Our HOA guide covers what associations typically require.
The Best Time of Year
Any time works in South Florida - there's no dormant season. That said, cleaning at the end of the rainy season, around October or November, gets the most out of a single visit. Growth from the wet months comes off, and you head into the drier stretch with clean surfaces that stay that way longer.
If you're only cleaning once a year, make it then.
Making It Automatic
Most people don't forget on purpose - they just don't notice the drift until it's obvious. That's the whole reason our recurring plans exist: we schedule it so you don't have to track it, and the property never gets far enough gone to need aggressive cleaning to recover.
Either way, put it on a schedule. In this climate, reactive cleaning is always more expensive than preventive.