Understanding Artillery Fungus and Why It Sticks to Your Siding

Artillery fungus is a common and frustrating problem for many homeowners. Those small black dots you see splattered on your siding are not just dirt or mold. They come from a fungus that shoots tiny spores, leaving marks that are tough to remove. If you’ve noticed these black spots, especially above flower beds or mulch areas, you’re likely dealing with artillery fungus. This post will explain what artillery fungus is, why it appears on your siding, why soft washing and pressure washing won’t get rid of it, and what you can do to protect your home.

Black artillery fungus spores on siding above mulch bed

What Is Artillery Fungus?

Artillery fungus is a type of fungus that grows in mulch and moist soil. It gets its name from the way it spreads spores: it literally shoots tiny black spores into the air, which then land on nearby surfaces like your house siding, windows, and even cars. These spores look like small black dots or splatters and can be mistaken for dirt or mold.

The fungus thrives in damp, shaded areas where mulch is present. It is especially common in areas with wood mulch, which provides the perfect environment for the fungus to grow and reproduce. Once the spores land on your siding, they stick firmly and create those stubborn black marks.

Why Does Artillery Fungus Appear on Siding?

The main source of artillery fungus is your mulch. If you have flower beds or landscaping with wood mulch near your home, you are more likely to see these black dots on the siding above those areas. The fungus grows in the mulch and shoots spores upward, which then land on the siding.

Several factors contribute to the presence of artillery fungus on your siding:

• Proximity to mulch: The closer your siding is to mulch beds, the higher the chance of spores landing on it.

• Moisture: Artillery fungus thrives in moist environments. Frequent watering or rain keeps the mulch damp, encouraging fungal growth.

• Shade: Shaded areas tend to stay moist longer, providing a better environment for the fungus.

• Type of mulch: Wood mulch is more likely to harbor artillery fungus than rubber or stone mulch.

  
  

Because the spores are shot with force, they can reach siding several feet above the mulch bed, explaining why you often see black dots higher up on your home’s exterior.

Why Soft Washing and Pressure Washing Won’t Remove Artillery Fungus

Many homeowners try to clean artillery fungus with soft washing or pressure washing, but these methods usually don’t work. Here’s why:

• Soft washing uses low-pressure water combined with cleaning solutions to remove dirt, algae, and some mold. However, artillery fungus spores are very stubborn and often embedded in tiny crevices on the siding. Soft washing may remove surface dirt but won’t fully eliminate the spores.

• Pressure washing uses high-pressure water to blast away grime. While it can remove loose dirt and some stains, it often fails to remove artillery fungus spores completely. The spores are sticky and can survive the water blast, leaving black dots behind.

  
  

In some cases, pressure washing can even damage siding or force spores deeper into cracks, making the problem worse. Because of this, relying on pressure washing alone is not an effective solution for artillery fungus.

What Can You Do About Artillery Fungus?

If you spot artillery fungus on your siding, it’s a sign that your home needs a thorough cleaning and some preventive steps. Here are practical tips to manage and reduce artillery fungus:

1. Replace or Change Your Mulch

Since mulch is the source of artillery fungus, changing it can reduce the problem:

• Switch to inorganic mulch like rubber, gravel, or stone, which does not support fungal growth.

• If you prefer wood mulch, choose types less prone to fungus, such as cedar or cypress.

• Keep mulch beds dry by avoiding overwatering and improving drainage.

  
  

2. Maintain Distance Between Mulch and Siding

Create a buffer zone between mulch beds and your siding:

• Leave a few inches of bare soil or gravel between mulch and the house.

• Consider installing edging to keep mulch away from siding surfaces.

  
  

3. Use Fungicide Treatments

Some fungicides can help control artillery fungus in mulch beds:

• Apply fungicide sprays designed for wood mulch to reduce fungal growth.

• Follow product instructions carefully and reapply as needed during wet seasons.

  
  

4. Schedule a Professional House Wash

If you have artillery fungus, you are likely overdue for a house wash. A professional cleaning service can:

• Use specialized cleaning agents that target fungal spores.

• Apply treatments that prevent spores from sticking back to siding.

• Clean your home safely without damaging siding materials.

  
  

Professional house washing is more effective than DIY pressure washing because it combines the right chemicals and techniques to remove artillery fungus.

How to Prevent Artillery Fungus from Returning

Once you have removed artillery fungus, preventing it from coming back is key. Here are some ongoing maintenance tips:

• Keep mulch dry: Avoid excessive watering near mulch beds.

• Improve sunlight exposure: Trim trees or bushes to reduce shade on mulch.

• Regular cleaning: Schedule house washing every 1-2 years to keep siding clean.

• Mulch management: Refresh mulch regularly and remove old, decaying mulch.

  
  

By following these steps, you can reduce the chances of artillery fungus spores landing and sticking to your siding.

Why Artillery Fungus Signals You Need a House Wash

Seeing artillery fungus on your siding is more than just an aesthetic issue. It indicates that your home’s exterior needs attention. Over time, fungal spores and other contaminants can damage siding materials, leading to costly repairs.

A professional house wash not only removes artillery fungus but also:

• Removes dirt, pollen, and algae buildup.

• Protects siding from long-term damage.

• Improves curb appeal and home value.

  
  

Ignoring artillery fungus means letting spores accumulate, which can make cleaning harder and increase the risk of siding deterioration.