How Freezing Temperatures Affect Algae and Mildew on Your Home

Homeowners often assume that cold winter weather takes care of algae and mildew on their home’s exterior. After all, if plants die in freezing temperatures, shouldn’t algae and mildew disappear too?

Unfortunately, that’s not how it works.

At Proline Pressure Washing, LLC, we frequently get calls in early spring from homeowners who are surprised by how quickly green, black, and brown staining returns. The reason is simple: freezing temperatures slow algae and mildew down, but they do not eliminate them.

What Happens to Algae and Mildew Below Freezing

When temperatures drop below 32°F, most organic growth on your home enters a dormant state.

• Algae and mildew stop actively growing

• Discoloration may fade slightly

• The organisms remain firmly attached to the surface

Rather than dying, these contaminants essentially go into hibernation. Their structure stays intact on siding, roofing, concrete, and masonry, waiting for favorable conditions to return.

Why Algae Survives Winter

Roof and siding algae are especially resilient. Many species have protective outer layers that allow them to withstand freezing temperatures. On roofing materials, algae can live inside microscopic pores and beneath shingle granules where they are shielded from the cold.

As soon as temperatures climb above the mid‑40s and moisture returns, algae resumes growth — often spreading faster than before.

Why Mildew Always Comes Back

Mildew spreads through airborne spores, and these spores are incredibly tough. Freezing weather does not kill them. Instead, spores remain dormant on exterior surfaces and in the air.

When spring brings warmth, humidity, and pollen, mildew finds the perfect environment to rapidly recolonize your home’s exterior.

The Spring Surge Homeowners Notice

Winter weather can actually make spring growth worse.

• Expansion and contraction of siding and roofing creates tiny cracks

• These cracks trap moisture

• Spring pollen provides an abundant food source

This combination causes algae and mildew to reappear quickly, making it seem like your home became dirty overnight.

Why Pressure Washing Alone Isn’t Enough

Simply washing the surface may improve appearance temporarily, but it does not address the root of the problem. Without proper treatment, algae and mildew will return.

Professional soft washing uses carefully controlled cleaning solutions that:

• Kill organic growth at the source

• Penetrate porous surfaces

• Remove staining safely without damaging siding or roofing

This approach provides results that last far longer than water alone.

Is Winter a Good Time to Clean?

Yes — and many homeowners don’t realize this.

During cooler months:

• Growth is less active

• Treatments are more effective

• Results often last longer into spring

A professional exterior cleaning before spring can significantly reduce how fast algae and mildew return.

The Bottom Line

Cold weather does not solve algae and mildew problems. It only pauses them.

If organic growth is not properly removed, it will return as soon as conditions improve — often faster and more aggressively.

If you want long‑lasting results and a cleaner exterior year‑round, professional cleaning is the solution.

Schedule Your Free Estimate

If you’re noticing stains on your roof, siding, driveway, or other exterior surfaces, Proline Pressure Washing, LLC is here to help.

• Visit our Home Page: https://www.prolinepressurewash.com/

• Contact us for a Free Estimate: https://www.prolinepressurewash.com/contact

We proudly serve homeowners and businesses throughout Metro Atlanta with professional pressure washing and soft wash services designed to protect your property and keep it looking its best.