Sarasota patios grow algae and mildew more than they collect dirt. Here is the right order - sweep, pre-wet, let a cleaning solution dwell, then rinse with a surface cleaner - and how to avoid stripes, plant burn, and a slick sealer.
A concrete patio in Sarasota does not get dirty the way a patio up north does. It grows things. The short version: sweep it, pre-wet it, put down a cleaning solution and let it dwell for ten minutes, then rinse with a surface cleaner at moderate pressure rather than carving at it with a zero-degree tip. The soap does the work on organic growth; the pressure only rinses away what the soap has already killed. Get that order backwards and you will spend an afternoon etching stripes into your own slab.
Most of what darkens a Suncoast patio is biological, not dirt. The green film is algae. The black spotting and streaking is usually mildew and a hardy blue-green algae that colonizes anywhere staying damp long enough. Our climate is close to ideal for it: long humid stretches, afternoon storms through the wet season that wet the slab daily, and heavy shade from live oaks that keeps it from ever fully drying.
This matters because organic growth has roots into the surface pores. Blasting the top layer off makes the patio look clean for a few weeks and then it returns faster than before, because you have opened the pores and left the growth behind. A cleaning solution kills it; pressure alone just gives it a haircut.
Not every patio around here is the same material, and the wrong approach on the wrong surface is where the expensive mistakes happen.
If you cannot tell what you have, flick a little water on it. A surface that darkens immediately is porous and unsealed. One that beads is sealed or coated, and it needs the gentler track.
This is the step that separates a good weekend from an expensive one. A cleaning solution strong enough to kill algae is strong enough to burn the landscaping you have been coaxing along all summer. Water your beds down thoroughly before you start, so the foliage is already saturated and cannot take up much of anything else, and rinse them again when you are finished.
Pay attention to where your runoff goes. A lot of patios here drain toward a bed, a swale, or a seawall, and around here that often means it ends toward a canal or a bay. Rinse generously, spread the runoff out rather than concentrating it into one channel, and do not let a puddle of concentrated solution sit against the base of a plant.
Sweep every bit of loose material off first. Wet oak leaves and grass clippings turn into a paste that a surface cleaner will smear around instead of removing, and any grit left on the slab becomes ammunition under pressure.
Then wet the whole patio with plain water before applying anything. A dry slab drinks the solution straight into the pores, which wastes it and makes streaking more likely. A pre-wet slab holds the solution on the surface where the growth actually is.
Put the solution down with the pump sprayer and leave it alone for about ten minutes. Watch it rather than timing it blindly. You will see the black spotting fade and the green go pale, which is the visual cue that it has done its job.
Do not let it dry on the slab. On a bright afternoon in July that can happen fast, which is why the whole job is easier in the early morning, in the evening, or on an overcast day. If an area starts drying, mist it lightly to keep it wet. If the patio is large, work in sections you can actually keep wet rather than soaking the entire thing at once.
Badly colonized patios often want a second application rather than more pressure. A second dwell is free. A slab you have etched is permanent.
Most residential concrete cleans well in the range of roughly 2,000 to 3,000 PSI through a surface cleaner. What actually damages concrete is not the machine's rating so much as concentrating that force into a tiny area and holding it there, which is exactly what a narrow tip at close range does. We go into the failure modes in more detail in our guide on whether pressure washing damages concrete.
Shell aggregate, older slabs, and anything coated should be treated as a low-pressure job where the chemistry does nearly all of the work. That is the same logic behind soft washing versus pressure washing.
Zebra striping is the signature of a patio cleaned with a wand. It happens because a wand cleans in a narrow arc, and overlapping arcs never land evenly, so you get alternating bands of clean and less-clean that show up the moment the slab dries.
A surface cleaner solves it by holding two spinning jets at a fixed height inside a housing, cleaning a consistent path. Use it in slow, straight, overlapping passes, and overlap each pass by a few inches. Do not rush, and do not stop moving while the trigger is down.
For edges and corners the surface cleaner cannot reach, switch to the wand with a wide tip, keep it moving, and hold it further back than feels necessary. Feather these edge passes into the cleaned field rather than stopping at a hard line.
When the patio dries and something is still there, it is almost always not organic and needs a different product.
None of these come out with a hypochlorite mix, and more pressure only etches around them and makes the halo worse. They need a dedicated rust or oxalic-based remover. The same applies to grease and oil, which we cover separately in removing oil and rust stains.
Plenty of Sarasota patios run straight into a pool deck and a screen enclosure, and the transition is where people cause damage. The deck coating is often a textured cool-deck product that will not survive what the open slab shrugs off, and the enclosure has its own rules entirely. Keep the pressure off the screen mesh and the frame, and handle that portion the way we describe in cleaning a pool cage and lanai.
Keep solution out of the pool itself. Cover what you can, rinse toward a drain rather than the waterline, and check the chemistry afterward if any overspray reached the water.
Sealing a clean, fully dry slab slows down how fast growth gets back into the pores, and it makes the next cleaning easier. Two local cautions are worth stating plainly.
First, the slab must be genuinely dry, not dry-looking. Sealing over trapped moisture in our humidity is how you get a cloudy white haze, and removing that is a bigger job than the cleaning was. Give it a few dry days, which in the wet season may mean waiting for a real break in the pattern rather than a clear afternoon.
Second, a glossy sealer on a pool deck can be slick when wet. If the patio is a walking surface around water, choose a matte penetrating sealer or one with a texture additive rather than a film-forming gloss.
Most patios here want attention about once a year, with shaded and north-facing slabs closer to every eight or nine months because they stay damp longest. A patio under heavy oak cover, or one that sits in a low spot where water stands after a storm, will always be on the shorter end. We cover the full cadence for the rest of the house in our guide on how often to pressure wash a house.
A reasonable middle ground is to rinse the slab down with plain water a few times a year and do the full solution-and-dwell cleaning annually. Keeping it from ever getting badly colonized is far less work than recovering it once it has.
Doing this yourself is genuinely reasonable on a straightforward broom-finished slab. It is worth getting help when the patio is coated or shell aggregate and a mistake is permanent, when it wraps a pool and screen enclosure with three surfaces meeting at once, when there is real staining that needs specific chemistry rather than a stronger machine, or when the runoff has nowhere good to go and needs controlling.
If you would rather not spend the weekend on it, you can see what pressure washing in Sarasota involves and what to expect from a proper job.
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