Venus Flytrap Browning Leaves & Dark Moss: Diagnosing Soil, Water, or Fungus

A Venus flytrap growing outdoors with 6+ hours of eastern sun suddenly develops browning leaves and a dark, slimy layer at the base. Is it fungus? Mineral buildup? Here’s how to narrow it down.

Step 1: Check Your Water

Tap water often contains dissolved minerals that accumulate in the soil, burning roots and causing leaf die‑back. Use only distilled, rain, or reverse‑osmosis water. If you’ve been using tap or spring water, repot immediately into fresh peat/perlite (1:1).

Step 2: Inspect the Soil

If the plant came from a big‑box store, the soil may contain fertilizer or inappropriate components. Repot into a clean 50/50 mix of sphagnum peat moss and perlite (from a bale, not a small bag).

Step 3: Assess the “Dark Moss”

True fungal attacks are sudden and lethal. A dark layer on the soil surface is often just algae or decomposed peat—not necessarily pathogenic. If the plant is still producing new growth, it’s likely not a fatal fungus.

Step 4: Provide Optimal Conditions

• Full, direct sun (not just bright indirect).
• Pot sitting in ~1 inch of pure water.
• No fertilization—ever.

If problems persist, send a photo showing the whole plant, pot, and growing area for a precise diagnosis.

Good growing!