Plume vs Mold

One of the most misunderstood topics among cigar enthusiasts—especially new smokers—is the difference between plume (also called "bloom") and mold. Both can appear as white or grayish spots on the surface of a cigar, but one is completely natural and even desirable, while the other can ruin the cigar if left unchecked.

Understanding how to distinguish plume from mold is essential for anyone storing cigars in a humidor or aging their collection long-term.

Side-by-side comparison of cigars with plume and mold

What Is Plume?

Plume is a fine, white, powdery substance that develops on the surface of a cigar as essential oils crystallize and rise to the wrapper over time. It is a sign that the cigar has been properly aged and stored in stable humidity conditions.

Key characteristics of plume:

  • Appears as a uniform, silky white or gray dusting
  • Wipes off easily with a dry cloth or brush
  • Doesn’t smell foul or musty
  • Typically forms evenly across multiple cigars in the same box

Plume is most common in cigars that have been aged for a year or more, especially in well-seasoned humidors. Some collectors even see it as a badge of quality, indicating a cigar that’s rich with natural oils.

What Is Mold?

Mold, on the other hand, is a fungal growth caused by excessive humidity (typically above 75% RH) and poor air circulation in a humidor. Unlike plume, mold is a serious problem that can spread quickly and compromise entire boxes of cigars.

Key characteristics of mold:

  • Appears as fuzzy or fuzzy-looking patches—white, green, blue, or even black
  • Has a musty, sour, or damp odor
  • Feels slightly wet or spongy to the touch
  • Doesn’t wipe off easily and may reappear
  • Often forms in irregular blotches or spots, sometimes only on a few cigars

If you spot mold on a cigar, remove it immediately and inspect the rest of your humidor. In most cases, mold makes the cigar unsmokable—especially if it has penetrated the foot or filler.

How to Tell the Difference

Feature Plume Mold
Color Light white or gray White, green, blue, or black
Texture Powdery, dry Fuzzy or wet
Spread Evenly across cigars Patchy, irregular
Smell No smell or sweet tobacco Musty, sour, damp
Removal Wipes off cleanly Stains or reappears
Safety Safe to smoke Unsafe and should be discarded

Prevention Tips

To avoid mold and promote natural plume:

  • Keep humidor RH between 65%–70%
  • Avoid overfilling your humidor—allow airflow
  • Use distilled water or propylene glycol in humidification systems
  • Rotate and inspect cigars regularly
  • Clean your humidor every 6–12 months

While plume is rare and not guaranteed, it typically forms only under stable, long-term aging conditions.

Summary

Plume vs mold is a distinction that every cigar lover should understand. Plume is harmless and may even enhance the cigar’s smoothness and flavor. Mold, however, is a warning sign of mismanaged humidity and should be taken seriously. When in doubt, inspect texture, smell, and consistency—your cigars (and your health) depend on it.