The Cedar Revival: How to Clean Your Cedar Fence the Right Way

If you live in Southwest Washington, you know that a cedar fence isn't just a boundary—it’s a major investment in your home’s curb appeal. But between the misty mornings in Toutle and the rainy winters across Cowlitz and Clark counties, that beautiful golden cedar can quickly turn gray and become a breeding ground for the "Pacific Northwest Green"—otherwise known as algae, moss, and mildew.

While it’s tempting to grab a pressure washer and blast the grime away, that is the quickest way to ruin a cedar fence. Because cedar is a softwood, it requires a "chemistry-first" approach rather than a "force-first" one.

Here is the professional procedure for cleaning cedar fences to ensure they last for decades.

1. Why Chemistry Beats Pressure

Cedar's beauty comes from its long, straight fibers and natural oils. High-pressure water (anything over 1,500 PSI) acts like a tiny chisel, carving into the wood, shredding those fibers, and leaving behind a "fuzzy" or splintered texture. Once those fibers are blown open, the wood absorbs even more water, which can accelerate decay.

By using the correct cleaning agents—a process called Soft Washing—we let the cleansers do the heavy lifting. This preserves the wood's structural integrity while reaching deep into the grain to kill the organic spores that cause regrowth.

2. The Right Cleansers for the Job

To get rid of that stubborn green algae without damaging your yard or your fence, you need the right mix.

• Oxygen Bleach (Sodium Percarbonate): This is the "gold standard" for cedar. Unlike standard laundry bleach (chlorine), oxygen bleach is non-toxic to your lawn and plants. It breaks down into water and oxygen, lifting the gray oxidation and green algae without stripping the wood’s natural color.

• The "PNW Pro-Mix": For a standard annual clean, we recommend:

  • 3 Parts Warm Water

  • 1 Part Oxygen Bleach

  • A squirt of non-ammonia dish soap (this helps the cleaner "stick" to the vertical boards).

• Note on Chlorine Bleach: Avoid using high concentrations of chlorine bleach (Sodium Hypochlorite) on cedar. It can "blonde" the wood unnaturally and, more importantly, it can damage the lignin (the glue that holds wood fibers together), leading to premature decay.

3. The Professional Step-by-Step Procedure

Step 1: Prep & Hydrate

Before applying any cleaner, lightly mist the fence with a garden hose. You want the wood to be damp, not dripping. This "opens" the pores of the cedar and prevents the cleaning solution from soaking too deep too fast, which ensures the algae on the surface gets the full brunt of the cleanser.

Step 2: Apply the Solution

Using a pump sprayer (the kind you’d use for garden fertilizer), apply your oxygen bleach mix from the bottom up. Working from the bottom prevents "clean streaks" from running down dry boards, which can leave permanent marks.

Step 3: The "Dwell" Time

This is the most important step. Let the solution sit on the wood for 10 to 15 minutes. You’ll see it start to bubble—that’s the oxygen at work, physically lifting the algae and dirt out of the wood grain. Do not let it dry! If it starts to dry, mist it lightly with water to keep it active.

Step 4: Gentle Agitation

For stubborn green spots or heavy moss, use a soft-bristle brush (not wire!) to gently scrub the area. The cleanser should have done 90% of the work; the brush is just for the finishing touch.

Step 5: The Low-Pressure Rinse

Rinse the fence thoroughly from the top down using a standard garden hose with a spray nozzle. You’ll be amazed to see the original "golden" hue of the cedar return as the gray and green wash away.

4. The Importance of Post-Cleaning Care

Once your fence is clean, it is essentially "naked." The pores are open, and the wood is vulnerable to the sun.

• Dry Time: Wait at least 24 to 48 hours of dry weather before applying any stain or sealer.

• The Reward: A clean, dry fence will absorb stain much more evenly, providing a professional finish that will protect the wood from the next Washington winter.

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Need Help Restoring Your Perimeter?

Cleaning a fence is rewarding, but it’s also a lot of work—especially if you have a large property in Lewis, Clark or Cowlitz County. As a local expert in exterior home renovations, LaMoria Construction can handle the heavy lifting for you. We use professional-grade, eco-friendly cleansers to restore your cedar without the risk of pressure damage.

Contact us for a free quote.