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Plant diagnosis

Why does my aloe vera have brown spots?

Arabian-peninsula succulent that stores water in plump gel-filled leaves — sun-hungry, drought-adapted.

The 4 most likely causes

The cause of aloe vera brown spotsusually narrows to one of the items below, ranked by how often we see each in Growli's diagnostic chats. Work down the list — most readers find their answer in the top two.

  1. Fungal or bacterial leaf spot (Possible)
    Brown spots with yellow halos appearing on aloe vera, especially after water sat on the leaves overnight, are most often fungal or bacterial leaf spot. Remove affected leaves, water only at the soil line, improve airflow, and apply a copper fungicide if it spreads.
  2. Sunburn or intense direct sun (Possible)
    Bleached patches, papery brown spots, or crisped leaf surfaces on the south-facing side of aloe vera are sunburn. Acclimatise it more gradually after a move, or filter midday sun with a sheer curtain. Sunburn damage doesn't heal — wait for new growth.
  3. Overwatering or poor drainage (Likely)
    Aloe vera stores water in its leaves and stems, so the roots stay turgid even after long dry spells. When you water on a fixed weekly schedule the soil never fully dries, the roots suffocate, and the lower leaves go yellow and squishy. Aim for when the soil is completely dry, every 2-3 weeks.
  4. Pests sucking sap (Possible)
    Sap-sucking pests (aphids, spider mites, mealybugs, scale) all cause similar symptoms: yellow stippling, distorted new growth, sticky residue. Inspect leaf undersides and stem joints with strong light. Most are controlled with weekly insecticidal soap or a horticultural oil spray.

How to diagnose in 60 seconds

Run these quick checks before you change anything — the right fix depends on what you find.

The fix — step by step

This is the recovery sequence Growli walks users through for aloe vera with brown spots. Work through the steps in order; skipping ahead is the most common reason a plant fails to bounce back.

  1. Quarantine if you suspect disease. If spots look wet, are spreading, or have a yellow halo, move aloe vera away from your other plants until you have a diagnosis. Disinfect your tools between plants.
  2. Remove the worst-affected leaves. Snip off heavily spotted leaves at the base. Don't compost them — bag and bin to stop spore spread. Never remove more than 30% of foliage in one go.
  3. Switch to filtered or rain water. If you suspect tap-water damage, water with rainwater, distilled water, or tap water that has stood uncovered for 24 hours. Continue for 4-6 weeks before re-evaluating.
  4. Improve airflow and watering technique. Water at the soil line only — never on the leaves. Space aloe vera so leaves are not touching neighbouring plants. A small fan in stagnant rooms makes a surprising difference.
  5. Apply a treatment if needed. For active fungal spread, a copper-based fungicide applied weekly per the label is the standard remedy. For sunburn or fluoride damage, no treatment helps — just remove damaged leaves and wait for new growth.

When this can't be saved

Most cases of aloe vera brown spots are recoverable, but a few red flags point to a plant that has gone past the point of return. If you spot any of these, consider propagating a clean cutting and starting over.

Prevention

For aloe vera, the single biggest preventative is matching its native rhythm: when the soil is completely dry, every 2-3 weeks, a bright south-facing window with several hours of direct sun, and a free-draining pot with a working drainage hole. Water at the soil line, not the leaves, especially in the evening when leaves can't dry before nightfall. Switch to filtered or collected rainwater for sensitive species — it pays for itself in fewer crispy edges. Improve airflow around densely planted shelves with a small clip-on fan.

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