Published: March 17, 2025 · Last updated: March 19, 2026

Why Your Pavers Turn Black (and How to Fix It)

You spent good money on a beautiful paver patio, driveway, or walkway. It looked stunning when it was first installed: clean lines, rich color, a surface you were proud to show off. But somewhere along the way, things changed. The pavers started darkening. First in the corners and shaded areas, then spreading across the entire surface. Now your once-gorgeous hardscape looks dirty, neglected, and nothing like what you paid for.

If you live in Point Pleasant or anywhere along the Jersey Shore, this is an incredibly common problem. The good news is that it is fixable. Here is what is actually happening to your pavers and what you can do about it.

The Main Culprits: Algae, Mold, and Mildew

The black discoloration on your pavers is almost always biological. It is living organisms that have colonized the surface of the stone, concrete, or brick. The three most common offenders are algae, mold, and mildew, and in many cases, you are dealing with all three at once.

Algae is the most widespread cause. It starts as a thin, barely visible film and gradually darkens as the colony grows. Black algae, in particular, produces a pigment that gives pavers that characteristic dark, almost charcoal-like appearance. Green algae is more common in consistently wet areas, while black algae thrives in spots that alternate between wet and dry conditions, which describes most outdoor surfaces at the Jersey Shore.

Mold and mildew are fungi that feed on organic matter. They thrive in the same conditions as algae: moisture, warmth, and shade. Even a thin layer of dust, pollen, or decomposing leaves provides enough nutrients for mold to establish itself on paver surfaces. Once it takes hold, it spreads through microscopic root-like structures called hyphae that penetrate into the pores of the paver material.

Why the Jersey Shore Makes It Worse

Living near the ocean creates a perfect environment for biological growth on hardscapes. The humidity along the Jersey Shore is consistently higher than areas just a few miles inland. Morning dew is heavier, ocean mist carries moisture deep into neighborhoods, and the salt air creates a film on surfaces that actually retains moisture longer.

Point Pleasant and surrounding shore towns also experience significant temperature swings between seasons. Hot, humid summers accelerate biological growth, while mild, wet winters prevent surfaces from ever fully drying out. This year-round moisture cycle means that algae and mold never really go dormant. They slow down in cold weather but pick right back up as soon as temperatures rise.

If your pavers are in a shaded area, the problem is compounded. Trees, fences, and the shadows cast by your home itself block the sunlight that would otherwise help keep surfaces dry and inhospitable to growth. North-facing patios are particularly vulnerable, as they receive the least direct sunlight throughout the year.

Other Contributing Factors

Beyond biological growth, several other factors can contribute to pavers turning dark. Leaf stains are a common issue, especially in the fall. When wet leaves sit on pavers for extended periods, they release tannins that soak into the porous surface and leave behind dark, rust-colored stains that can look black when they accumulate.

Efflorescence is another possibility. This is a white, powdery deposit that forms when water moves through concrete or brick and carries mineral salts to the surface. While efflorescence itself is white, the cycle of moisture movement it represents also creates conditions favorable for biological growth, leading to a combination of mineral deposits and dark organic staining.

Oil and automotive fluid stains can also darken pavers, particularly on driveways. These petroleum-based stains attract dirt and create dark spots that are different from biological growth but often get lumped together in the homeowner’s mind as the same problem. They require different treatment approaches.

The DIY Approach and Its Limitations

Many homeowners try to tackle black pavers on their own, and there are some things you can do. A solution of white vinegar and water, applied with a scrub brush, can remove light surface algae. Oxygen bleach products (not chlorine bleach, which can discolor pavers) can handle moderate biological growth. And a consumer-grade pressure washer from the hardware store can blast off surface-level grime.

The problem with DIY approaches is that they typically address only the surface. The algae and mold you can see are just the tip of the iceberg. Their root systems extend below the surface of the paver, and if you only remove what is visible, regrowth happens quickly, often within just a few weeks. You end up in an exhausting cycle of cleaning and re-cleaning that never fully solves the problem.

Consumer pressure washers also carry risks. Too much pressure can erode the surface of concrete pavers, removing the top layer and exposing the aggregate underneath. This creates a rougher texture that actually makes it easier for algae to grip and grow back. Too much pressure can also blast out the joint sand between pavers, destabilizing the entire surface and requiring expensive re-sanding.

There is also the issue of time. A DIY paver cleaning project on a typical Point Pleasant patio can take an entire weekend of hard, back-breaking work. And without the right equipment and cleaning solutions, the results are rarely as good or as long-lasting as a professional job.

Professional Pressure Washing: The Real Solution

Professional pressure washing for pavers is different from the DIY approach in several important ways. First, professionals use commercial-grade equipment that delivers precise, consistent pressure. They know exactly how much force each type of paver material can handle without being damaged, and they adjust their technique accordingly.

Second, professional cleaning involves pre-treating the surface with specialized solutions that penetrate below the surface to kill biological growth at the root level. These are not the generic cleaners you find at the hardware store. They are professional-grade surfactants and biocides formulated specifically for hardscape cleaning. They break the bond between the organism and the paver surface, allowing everything to be rinsed away cleanly.

The combination of proper pre-treatment and controlled pressure washing produces results that are visibly superior to DIY methods. Pavers come out looking remarkably close to their original color, with uniform appearance across the entire surface. The difference is often so dramatic that homeowners think their pavers have been replaced rather than cleaned.

A professional cleaning also lasts significantly longer than a DIY effort. Because the biological growth is killed at the root rather than just removed from the surface, it takes much longer for new colonies to establish themselves. Most homeowners find that a professional cleaning keeps their pavers looking good for a full year or more, depending on conditions.

Sealing: The Key to Long-Term Protection

If you want to maximize the time between cleanings and keep your pavers looking their best for as long as possible, sealing is the answer. A quality paver sealant creates a protective barrier on the surface that makes it much harder for algae, mold, and mildew to take hold. It also helps prevent staining from leaves, oil, and other contaminants.

Sealing should always be done after a thorough cleaning. Applying sealant over dirty pavers just locks in the grime and biological growth, creating an even worse problem. The process is: clean first, let the pavers dry completely, then apply the sealant. For best results, this is a job for professionals who can ensure proper surface preparation and even sealant application.

There are two main types of paver sealant: film-forming and penetrating. Film-forming sealants create a visible sheen on the surface, which many homeowners like because it enhances the color of the pavers and gives them a “wet look.” Penetrating sealants soak into the paver material and provide protection without changing the appearance. Both are effective at preventing biological growth, so the choice comes down to aesthetic preference.

At the Jersey Shore, where moisture exposure is constant, a sealed paver surface can stay clean two to three times longer than an unsealed one. The upfront investment in sealing pays for itself by reducing the frequency of cleaning needed to keep your hardscape looking great.

Prevention Tips for Jersey Shore Homeowners

Beyond professional cleaning and sealing, there are steps you can take to slow down the blackening process. Keep your pavers as clear of debris as possible. Sweep leaves promptly in the fall rather than letting them sit and decompose on the surface. Trim back vegetation that creates excessive shade, if practical. Ensure that your downspouts direct water away from paver surfaces rather than onto them.

Good drainage is critical. If water pools on your pavers after rain and takes hours to evaporate, that standing water is fueling biological growth. Addressing drainage issues, whether through regrading, adding drains, or adjusting the slope of the paver surface, can significantly reduce the problem.

And schedule regular professional cleanings. An annual pressure wash, ideally in the spring, keeps biological growth from ever reaching the point where your pavers look black and neglected. It is much easier and more cost-effective to maintain a clean surface than to restore one that has been neglected for years.