Why does my string of hearts have brown spots?

The 4 most likely causes

The cause of string of hearts brown spots usually 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 string of hearts, 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 string of hearts 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)
   String of hearts 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 water thoroughly, then let the pot dry almost completely — 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.

Why string of hearts in particular

String of hearts likes bright light — plenty of it keeps the vines compact and the leaves well-marbled — but the thin succulent leaves can still scorch under fierce, unfiltered sun, especially through hot glass or after a sudden move outdoors. Sunburn shows as dry, bleached or brown patches on the most exposed upper leaves that won't recover. Introduce strong light gradually. Brown patches that are soft rather than dry, by contrast, point back toward overwatering and rot travelling up the stems.

Normal turnover, or real trouble?

These vines want bright light and there's no normal brown mottling to wait out; the healthy leaf is cleanly marbled silver and green. A tiny dry nick where a strand caught on something is cosmetic and stays fixed. Concern belongs to dry, bleached or brown patches on the most sun-exposed upper leaves after a jump in light, and to soft brown patches, which read instead as rot creeping up the stems.

How to diagnose in 60 seconds

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

• Are the spots dry and crisp or wet and spreading? Crisp = sunburn, fluoride, or old damage; wet = active fungal or bacterial spot.
• Do the spots have a yellow halo? Halos are classic for bacterial and fungal leaf spot.
• Are they only on the sunny side of the plant? That points to sunburn.
• Are the leaf tips uniformly brown while the rest is healthy? Crispy tips on string of hearts usually mean low humidity or tap-water minerals.

The fix — step by step

Tell scorch from rot first. For bleached patches after strong sun, pull the plant back from the hot glass and step light up gradually rather than all at once; the marked leaves won't mend but new growth stays clean. For soft brown patches travelling along a stem, cut the strand cleanly well above any discoloured, translucent section and re-root the firm top, rather than waiting for the rot to reach the tuber.

This is the recovery sequence Growli walks users through for string of hearts 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 string of hearts 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 string of hearts 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 string of hearts 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.

• Spots are spreading by several per day across multiple leaves — active aggressive disease.
• The whole crown of the plant is blackening from a central point outward.
• Healthy-looking neighbouring plants are starting to show the same symptoms.

Prevention

For string of hearts, the single biggest preventative is matching its native rhythm: water thoroughly, then let the pot dry almost completely — every 2-3 weeks, very bright light with some gentle 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.

Common questions

Related guides

• What's wrong with my plant? — the diagnosis apps compared
• Is string of hearts toxic to cats and dogs? — pet-safe, per the ASPCA
• How often to water string of hearts — the watering brief
• When to repot string of hearts — pot size and timing
• Brown spots on plants — the full diagnostic guide across species
• What's wrong with my plant? — Growli's flagship diagnosis index
• String of hearts — yellow leaves
• String of hearts — curling leaves
• String of hearts — drooping
• Monstera — brown spots