🍂 Why Does My Cannabis Plant Have Brown Spots or Streaks?Updated 2 days ago

If you're spotting brown patches or streaks on your cannabis leaves or stems — especially ones that seem like they can be scratched off — your plant might be trying to tell you something important 🧐

Let’s break it down and help you figure out what’s going on — and how to fix it! 🔍

🔎 Common Causes of Brown Spots or Streaks

1. Calcium Deficiency

• Symptoms: Rusty or brown speckles, especially on newer leaves.

• Feels crusty or rough to the touch — and sometimes flakes when scratched.

• Fix: Add a calcium supplement like Cal-Mag. Make sure your pH is around 6.2–6.5 in soil or 5.8–6.2 in hydro to allow nutrient uptake ⚖️

2. Leaf Septoria (Fungal Infection)

• Symptoms: Yellowing leaves with brown, dry spots that spread. Spots may look sunken or flake off.

• Cause: High humidity, poor airflow, or wet leaves — especially outdoors or in greenhouses 🌧️

• Fix:

  • Remove infected leaves immediately 🧼

  • Improve airflow with fans or spacing 🌬️

  • Apply an organic fungicide like neem oil or copper-based spray (early on only)

3. Rust Fungus

• Symptoms: Orange-brown powdery streaks or blotches on leaves or stems. Looks and feels like you can wipe or scratch it off — that’s fungal spores.

• Fix: Same steps as Septoria — remove affected areas and treat early. Prevent high humidity and stagnant air.

4. Pests or Physical Damage

• Some pests, like thrips or spider mites, can leave behind bronze/brown scarring that might peel or flake.

• Check under leaves with a loupe for tiny bugs or webbing.

🛠️ How to Treat & Prevent Further Damage

• Trim away heavily damaged leaves to slow spread and improve airflow ✂️

• Dial in your environment:

  • Humidity: 40–60%

  • Temp: 70–80°F (21–27°C)

  • Strong but not stagnant airflow

• pH matters! Make sure your water and soil are in range so your plants can access nutrients.

• Avoid overwatering, which encourages fungus and root problems.

🧪 Pro Tip: Take Notes!

Keeping a grow journal helps you track patterns and catch issues early next time — like when a nutrient deficiency starts or when a fungus hits.

Still unsure if it’s a deficiency, pest, or fungus? Snap a photo and reach out to our team — we’re happy to take a look 👉 Contact us here

And don’t worry — with a little attention and cleanup, most cannabis plants bounce back beautifully 💚

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