Cleaning Cedar, Redwood, and Pressure-Treated Decks: A Wood-by-Wood Guide

Not all deck wood is the same, and cleaning it like it is will damage your deck.

Cedar is soft and porous. Redwood is rich in natural tannins that react to certain cleaners. Pressure-treated pine has chemistry embedded in the wood that changes how it responds to bleach. Use the wrong product or the wrong pressure on any of them and you can end up with a fuzzy surface, blotchy color, or a deck that grays out again faster than it should.

This guide breaks down the right cleaning method for each of the three most common deck woods, so you can match your approach to what your deck is actually made of.

Quick Reference: Which Wood Do You Have?

Before choosing a cleaning methods, confirm what your deck is made of. A quick way to tell:

• Cedar is light tan to reddish brown, has a distinctive aromatic scent when scratched or cut, and feels lightweight and soft. Boards often show visible knots.
• Redwood is deeper reddish brown to burgundy, dense and heavy, with a straight tight grain and few knots. Older redwood weathers to a silvery gray.
• Pressure-treated pine is usually greenish tinted when new (from the copper-based preservatives), fades to gray or tan with age, is heavier than cedar, and often has a stamped grade mark on one end. It is the most common deck wood in the United States.

If you are unsure, look at the end grain or the underside of a board for a stamp or preservative color.

Cleaning a Cedar Deck

Cedar is the softest of the three woods on this list, which changes everything about how it should be cleaned.

What Makes Cedar Different

Cedar has a low density and a porous surface. It absorbs cleaner easily, but it also damages easily. High pressure, stiff brushes, or aggressive chemistry will fuzz the surface within minutes and leave the deck feeling rough for months.

Cedar is also naturally rot-resistant thanks to oils in the wood, but those same oils leach out over time, especially with harsh cleaners. Preserving them is part of preserving the deck.

The Right Cleaning Method for Cedar

1. Sweep the deck thoroughly and remove furniture.
2. Pre-wet surrounding plants and grass to dilute any runoff.
3. Apply a biodegradable wood cleaner with a pump sprayer in 100 to 150 square foot zones. Avoid any product with chlorine bleach, which strips cedar’s natural oils and accelerates graying.
4. Let the cleaner dwell 10 to 15 minutes. Mist with water every few minutes if it starts drying out. Cedar dries fast.
5. Scrub gently with the grain using a soft to medium bristle synthetic brush. Never use stiff bristles or steel wool on cedar.
6. Rinse with a garden hose or a pressure washer at 1,000 to 1,200 PSI maximum, held 12 inches from the boards, with a 40-degree nozzle. Cedar is soft enough that a garden hose is often the safer choice.
7. Apply a wood brightener to neutralize the cleaner and restore the wood’s pH.
8. Let the deck dry 48 to 72 hours before staining.

What to Avoid on Cedar

• Chlorine bleach based cleaners
• Pressure washing above 1,500 PSI
• Stiff bristle brushes
• Scrubbing against the grain
• Sanding as a shortcut for cleaning (creates permanent fuzzing)

Cleaning a Redwood Deck

Redwood is denser and more durable than cedar, but it has its own quirk: it is loaded with natural tannins that react to certain cleaners and to metal fasteners.

What Makes Redwood Different

Redwood tannins are what give the wood its deep reddish color, but they also cause two common problems:

• Tannin bleed creates dark streaks or blotches, especially around nails and screws or where water pools.
• Iron reactions turn the wood dark blue or black wherever ferrous metal fasteners have oxidized.

Both problems respond to the right cleaner and brightener sequence, but neither responds well to chlorine bleach, which locks tannins into the wood permanently.

The Right Cleaning Method for Redwood

1. Sweep the deck and remove furniture.
2. Pre-wet plants and grass around the deck.
3. Apply a biodegradable wood cleaner without chlorine bleach. Redwood is more forgiving than cedar with dwell times and slightly firmer scrubbing, but the “no bleach” rule is absolute.
4. Let the cleaner dwell 15 to 20 minutes, misting to keep the surface wet.
5. Scrub with the grain using a medium bristle brush. Work full board lengths at a time to avoid lap marks in the color.
6. Rinse with a garden hose or pressure washer at 1,200 to 1,500 PSI, 12 inches from the boards, 25-degree nozzle.
7. Always apply a wood brightener on redwood. This step is even more important than on other woods because oxalic acid lifts the iron and tannin stains that redwood is prone to.
8. Let the deck dry 48 hours before staining.

What to Avoid on Redwood

• Chlorine bleach (locks tannins in permanently, causes long-term darkening)
• Skipping the brightener step (redwood shows tannin and iron stains more than any other common deck wood)
• Cleaners containing sodium hypochlorite even at low concentrations
• Aggressive scrubbing across the grain

Cleaning a Pressure-Treated Deck

Pressure-treated wood is the most common deck material in the United States, and it is also the most misunderstood when it comes to cleaning. The chemistry embedded in the wood changes how it should be handled.

What Makes Pressure-Treated Wood Different

Modern pressure-treated lumber is infused with copper-based preservatives (ACQ, MCA, or CA-B in most cases). Those preservatives make the wood rot resistant, but they react with certain cleaners in ways that cedar and redwood do not.

Specifically:

• Chlorine bleach reacts with the copper preservatives, leaving the wood with an unnatural whitewashed look and reducing the effectiveness of the treatment over time.
• Pressure-treated pine is often denser than cedar but still relatively soft, so pressure washing needs care.
• New pressure-treated wood often has a green or brown tint that needs to fade and be cleaned before any stain will bond.

The Right Cleaning Method for Pressure-Treated Wood

1. Confirm the deck has weathered enough to stain. New pressure-treated lumber often needs 3 to 6 months (sometimes longer) to release enough of its moisture and surface chemistry before it can accept stain. Cleaning is fine at any point, but staining is not.
2. Sweep the deck and remove furniture.
3. Pre-wet plants and grass to protect from runoff.
4. Apply an oxygenated or biodegradable liquid cleaner without chlorine bleach. Sodium percarbonate based products work well on pressure-treated pine because they lift dirt and graying without damaging the preservative chemistry.
5. Let the cleaner dwell 10 to 15 minutes, misting to keep wet.
6. Scrub with the grain using a medium to stiff synthetic bristle brush. Pressure-treated pine tolerates slightly more scrubbing pressure than cedar.
7. Rinse with a pressure washer at 1,200 to 1,500 PSI, 12 inches from the boards, 25-degree nozzle. Or use a garden hose if you prefer to be conservative.
8. Apply a wood brightener to neutralize the cleaner.
9. Let the deck dry 48 hours before staining.

What to Avoid on Pressure-Treated Wood

• Chlorine bleach (reacts with copper preservatives)
• Staining brand new pressure-treated wood before it has weathered
• Pressure washing above 1,500 PSI (the wood is softer than it looks)
• Assuming pressure-treated means “does not need cleaning” (the surface fibers still gray and hold mildew like any other wood)

The One Rule That Applies to All Three Woods

Regardless of species, three things matter for every deck cleaning job:

1. Skip the chlorine bleach. It damages cedar oils, locks in redwood tannins, and reacts with pressure-treated preservatives. There is no wood species where chlorine bleach is the right choice.
2. Always brighten after cleaning. Every cleaner raises the wood’s pH, and every wood species benefits from having that pH neutralized before staining.
3. Let the wood dry fully. Cedar, redwood, and pressure-treated pine all need 48 to 72 hours of dry weather before stain will bond properly.

A biodegradable liquid cleaner like Hemp Shield Wood Deck Cleaner is formulated to work safely across all three wood types. It handles the fiber-dissolving work on weathered cedar, the tannin lifting on redwood, and the graying on pressure-treated pine without any of the chemistry that damages any of them.

Quick Comparison Table

For readers who want the summary at a glance:

The Bottom Line

Cedar wants gentleness. Redwood wants tannin management. Pressure-treated wood wants preservative-safe chemistry. All three want the same core process: a biodegradable cleaner, a proper brightener, careful pressure, and full drying before stain goes on.

Match your method to your wood, avoid chlorine bleach across the board, and any of these three deck types will clean up beautifully and hold a stain for years.

Frequently Asked Questions (FAQs)

Q.1 Can I use the same deck cleaner on cedar, redwood, and pressure-treated wood?

Yes, a quality biodegradable liquid or oxygenated wood cleaner without chlorine bleach works safely on all three wood types. What changes between species is the technique, not the product. Cedar needs gentler scrubbing and lower pressure, redwood needs longer dwell time and always requires a brightener afterward, and pressure-treated wood needs a bleach-free formula that will not react with copper preservatives. One well-chosen cleaner can handle all three decks in the same yard.

Q.2 Is bleach safe to use on a pressure-treated deck?

No. Chlorine bleach reacts with the copper-based preservatives in modern pressure-treated lumber, leaving the wood with an unnatural whitewashed appearance and reducing the effectiveness of the preservative treatment over time. It also damages surrounding plants and corrodes metal fasteners. Use a biodegradable oxygenated or liquid wood cleaner without chlorine bleach for pressure-treated decks.

Q.3 How do I clean a cedar deck without damaging the wood?

Clean a cedar deck by using a biodegradable cleaner without chlorine bleach, scrubbing gently with the grain using a soft to medium synthetic brush, and rinsing with a garden hose or a pressure washer set at 1,200 PSI or less. Cedar is softer and more porous than most other deck woods, so aggressive pressure washing or stiff bristles will fuzz the surface and leave it rough. Always apply a wood brightener after cleaning to neutralize the pH before staining.

Q.4 Why is my redwood deck turning dark after cleaning?

Redwood turning dark after cleaning usually points to unreacted tannins or iron staining from metal fasteners. Both problems are fixed with an oxalic acid based wood brightener applied after the cleaner. If chlorine bleach was used during cleaning, the darkening may be permanent because bleach locks tannins into the wood. Reclean the deck with a biodegradable non-bleach cleaner, apply a brightener, and the natural color should return.

Q.5 How long does new pressure-treated wood need to weather before staining?

New pressure-treated wood typically needs 3 to 6 months of weathering, sometimes longer, before it can accept stain properly. The freshly treated wood contains excess moisture and surface chemistry that prevents stain from bonding. A simple test: sprinkle water on the surface. If the water beads up, the wood is not ready. If the water absorbs within 10 minutes, the wood is dry enough to clean, brighten, and stain. Cleaning is safe at any point, even on brand new pressure-treated wood.