Mildew on Stucco Homes in Lakeland: Why It Happens and How to Fix It

If you own a stucco home in Lakeland, Winter Haven, or anywhere in Polk County, you’ve almost certainly seen the streaks. Vertical grey-green stains running down the wall from the soffit. Dark patches on the shaded north side. Sometimes a pinkish algae bloom in particularly humid corners. It looks like dirt. It isn’t.

What you’re seeing is mildew and algae — and pressure washing alone, even hard pressure washing, won’t fix it. This guide explains why stucco in Florida is so vulnerable, what makes the staining come back faster than other siding types, and the right way to clean it.

Why stucco grows mildew so fast in Florida

Stucco is a porous, mineral-based surface. The texture that gives stucco its character — the small pits, ridges, and irregularities — is also the texture that holds moisture against the wall after every rain. Combine that with:

• High humidity in central Florida (Lakeland’s average summer humidity sits around 75-90%)
• Mature tree cover that shades north-facing walls for most of the day, preventing the wall from drying
• Sprinkler overspray that hits walls regularly with mineral-laden water
• Oak pollen that settles into the stucco pores in spring and feeds the next generation of organic growth

The result is a surface that stays damp longer than smooth siding does, and that damp surface is perfect for two organisms:

Mildew (a surface mold) grows in the pores, producing the grey-green discoloration. It’s the dominant Lakeland staining issue.

Algae (often Trentepohlia, a different species than the black roof algae) sometimes blooms in particularly humid corners, producing the rust-orange or pinkish staining you see on north-facing walls near landscaping.

Both feed on the trace organic matter in pollen, dust, and rainwater. Neither is dirt. Both grow in the actual stucco surface, not just on top of it.

Why pressure washing alone doesn’t fix it

This is the part most homeowners get wrong, and it’s not their fault — every YouTube tutorial shows someone blasting stucco with a wand and the dirt visibly coming off. The problem is that the visible dirt comes off, but the mildew embedded in the stucco pores doesn’t. Within 6 to 12 months (often faster on north-facing walls), the staining is back, often worse than before.

There’s a second problem: high pressure damages stucco. The surface is mineral and brittle. Hitting it with 3,000+ PSI at close range can chip the texture, force water deep into the wall, and even open up cracks at expansion joints. In a Florida hurricane-zone home, water in the wall is a serious problem — it leads to substrate rot, indoor mold, and stucco delamination. Pressure-washing stucco the wrong way creates expensive damage that the homeowner doesn’t see until months later.

What actually works: soft-wash with a mildewcide

The right approach to stucco mildew is a soft-wash treatment. The method:

1. Pre-wet the surface and surrounding landscaping to prevent the chemistry from over-concentrating.
2. Apply a sodium hypochlorite-based cleaning agent (the same family of chemistry that works on roof algae) at low pressure — closer to garden-hose pressure than pressure-wash pressure.
3. Dwell for 5 to 15 minutes (long enough for the chemistry to penetrate the pores and kill the mildew at the root).
4. Rinse thoroughly with low-pressure clean water, working top-down.

The visible result is dramatic — stucco that looked grey-green or grey-pink comes back to its original tone, and unlike pressure-washing-only, the mildew doesn’t come back in 6 months because it was killed at the root, not just rinsed off the surface.

A typical Lakeland stucco home (single-story, 2,000 sq ft of wall) takes 2 to 3 hours and includes the soft-wash, window frame and soffit cleaning, and a final rinse of the landscaping. Two-story stucco homes run 3 to 4 hours.

What it costs in Lakeland

Soft-wash cleaning of a stucco home in Polk County runs:

• Single-story stucco home (under 2,000 sq ft): $200 to $375
• Two-story stucco home: $350 to $600
• Combo with roof cleaning and driveway: $700 to $1,200 for the full property

See the full 2026 cost guide for pressure washing in Lakeland for context on combo pricing.

How often a Lakeland stucco home needs cleaning

For most properties in Polk County, once a year is the right cadence. The variables:

• North-facing walls in heavy tree cover: may need an 8-to-10-month cycle
• Lakefront stucco homes (extra humidity): may also benefit from a faster cycle
• South-facing walls in direct sun: typically can stretch to 14 to 18 months
• Sprinkler-impacted walls (sprinklers hitting siding regularly): the mineral deposits add a complication — adjust sprinkler heads if you can, and clean annually regardless

Properties in Cleveland Heights, Lake Hollingsworth, and Lake Morton Historic District often have heavy oak cover and run on the faster end of the cadence. Newer subdivisions in South Lakeland and Highland City are usually annual.

What you can do yourself between professional washes

Two low-effort maintenance moves:

1. Adjust irrigation. Make sure sprinklers aren’t hitting the side of the house. Wet stucco is mildew-friendly stucco. A 15-minute irrigation audit can extend the wash cycle by 6 months.

2. Pressure-rinse (not pressure-wash) shaded corners with a garden hose every 2 to 3 months. A quick water-only rinse clears the pollen and dust that feed the next generation of mildew. This isn’t a substitute for the annual soft-wash, but it stretches the gap.

What not to do:

• Don’t use a consumer pressure washer at high PSI on stucco. The damage compounds over time.
• Don’t use bleach-only without the right surfactant. The dwell time and even coverage matter more than the chlorine concentration.
• Don’t rinse the wall with the sprinklers (a common DIY suggestion). It spreads the organic growth across more of the wall instead of removing it.

When to call a professional

If you see any of the following, it’s time for a soft-wash:

• Visible grey-green or rust-orange streaks on any wall
• Dark vertical staining below the soffit line
• A patchy “ghosting” pattern where the stucco color looks uneven
• A pink or salmon-colored algae bloom (more common in Winter Haven and Auburndale near the lakes)

We work across Lakeland, Auburndale, Bartow, Winter Haven, and all of Polk County routinely on stucco homes. Most jobs schedule within 3 to 7 days; listing-prep and time-sensitive work usually 24 to 48 hours.

For a same-day quote, text photos of the affected walls to (863) 887-6769. Fixed-price quote, no in-person visit needed.