Calathea Leaves Curling? 7 Quick Tests to Pinpoint the Real Cause

Calathea leaves curling is one of those panic-inducing plant moments. The plant looks dramatic, then suddenly it seems to curl up like it’s signaling distress. You’re not alone. I’ve treated more Calatheas than I care to admit, and I’ve learned that curling is a symptom, not a diagnosis. There isn’t one evil villain behind it—there are seven common culprits, and they each require a different fix. The trick is to test quickly, rule things out, and act with purpose.

If you’re short on time, skip the theory and go straight to the seven tests. Each one is a tiny, practical experiment you can run in your living room in under 10 minutes. And yes, you’ll get a printable two-column cheat sheet at the end you can tape to your pot rack for reference.

A quick reality check before we dive in: Calatheas are understory plants. They crave humidity, gentle light, and even moisture. When any one of those things shifts, curling often follows. I’ve seen it in my own collection multiple times. The first time it happened to a well-loved plant, I chased every possible cause at once—pests, lighting, soil, you name it. After a few weeks, I learned to run these seven tests in order and not panic when the leaves curled. The results were usually obvious, and the plant recovered faster than I expected.

Here’s the practical path I actually use. And a quick aside I learned from a busy weekend: your plant’s bark-up-the-tree signal isn’t a drama queen moment. It’s telling you, in a few telltale signs, exactly what to adjust. If you can read those signs, you can save a lot of leaf frustration.

Micro-moment: A few months ago, I moved a Calathea to a sunnier corner because I misread “bright indirect light” as “near a sunny window.” The curling worsened for two days. A tiny paint-drying moment helped me see the error—then I remembered the trusty tests and swapped to filtered light. The leaves unfurled in a day. It’s amazing how such a small cue (the way the light feels on your skin near a window) can tell you so much about a plant’s needs.

Test 1: The Pot-Weight Water Test Purpose: Is the plant under- or over-watered? It’s the simplest, most revealing starting point.

How to perform:

• Pick up the pot with your hand. Compare it to a healthy plant of similar size and soil, or recall the last time you watered and how heavy the pot felt afterward.

Expected outcomes and actions:

• Outcome A: The pot feels very light. Soil is bone dry.
  • Next action: Bottom-water the plant. Place the pot in a tray of water for 30-60 minutes so the soil can soak from the bottom through the drainage holes. After soaking, drain completely and let the surface dry slightly before watering again. If curls persist after rehydration, continue with the other tests to rule out other causes.
  • Real-world note: Bottom-watering transformed one Calathea that always curled after what I thought was a proper soak. The leaves unfurled within hours once the soil had a chance to hydrate evenly through the root zone.
• Outcome B: The pot feels very heavy, the top is damp, and it’s only a day or two after watering.
  • Next action: Likely overwatering. Let the top 2-3 inches of soil dry out completely before watering again. If curling continues or yellowing appears, jump to Test 7 (Repot Tug) to inspect roots.
• Outcome C: Moderately heavy. The top inch or two is damp but not soggy.
  • Next action: Watering isn’t the obvious issue. Move to Test 2 or Test 4 to check light or pests.

Test 2: Underside Pest Scan Purpose: Are pests the culprit? Spider mites, thrips, or whiteflies love to hide on the undersides.

How to perform:

• Use a bright light to inspect several leaves, especially curled ones, on the underside. Look for tiny insects, webbing, or a sticky film. Wipe a white paper towel along the underside; any color or residue on the towel is a clue.

Expected outcomes and actions:

• Outcome A: Tiny red/brown dots, fine webbing, or streaks on a paper towel.
  • Next action: Isolate the plant. Wash leaves with lukewarm water and a mild soap or insecticidal soap. For heavier infestations, considerNeem oil or a targeted non-neonicotinoid insecticide. Repeat every 5-7 days for 2-3 weeks to break the life cycle.
  • Personal note: Spider mites were my arch-nemesis last winter. After a week of repeated soapy sprays and a weekly rinse, the infestation dwindled and the curling eased as the leaf surfaces recovered.
• Outcome B: No visible pests or webbing.
  • Next action: Proceed to Test 3 or Test 4.

Test 3: The Soil Probe Purpose: Is the soil deeply dry, compacted, or waterlogged? Deep moisture and soil structure matter for Calatheas.

How to perform:

• Insert a finger or a moisture probe into the soil about 2-3 inches deep. Feel for moisture and resistance.

Expected outcomes and actions:

• Outcome A: Deep dryness with a hard, compact feel.
  • Next action: Under-watered and possibly compacted. Bottom-water or gently repot with fresh, light, well-draining soil if the issue recurs. If you’ve repotted recently and still see drought signs, check for root health in Test 7.
• Outcome B: Deeply soggy smell or slime in the soil.
  • Next action: Stop watering. Allow the soil to dry. If this persists, consider repotting to inspect the roots (Test 7).
• Outcome C: Moist but crumbly soil, not soggy.
  • Next action: Moisture level seems adequate; move on to environmental checks (Test 4 or 6).

Test 4: Light Meter Check (or Window Proximity) Purpose: Too much light or too little light are both curling culprits. Calatheas prefer bright, indirect light.

How to perform:

• Use a light meter app or just observe where the plant sits relative to windows. If you don’t have a meter, aim for a spot with filtered light or a few feet away from direct sun that comes through a window with a sheer curtain.

Expected outcomes and actions:

• Outcome A: Direct sun exposure or extremely high brightness for long periods.
  • Next action: Move the plant to a spot with indirect light or filter the sun with sheer curtains. If you’re seeing scorch marks or faded patterns, you’re likely over-exposed.
• Outcome B: Very low light (dim corners) or deep shade.
  • Next action: Gently move toward brighter indirect light. Curling here is less common but possible if the plant compensates by trapping energy and stressing tissues.
• Outcome C: Bright, indirect light (roughly 1,000-5,000 lux).
  • Next action: Light levels likely appropriate. Proceed to Test 5 or 6 to assess other drivers.

Test 5: Salt Crust Inspection Purpose: Mineral buildup from tap water or fertilizer can stress Calathea roots and cause curling.

How to perform:

• Inspect the soil surface and the rim of the pot for a white or yellow crust. Run your finger along the surface to feel for a crusty layer.

Expected outcomes and actions:

• Outcome A: White or yellow crust is visible.
  • Next action: Flush the soil. Run lukewarm distilled or rainwater through the pot from the top for several minutes. Let it drain completely. Consider using filtered water to prevent future buildup. If buildup is heavy or recurring, a repot (Test 7) may be necessary.
• Outcome B: No visible crust.
  • Next action: Move on to Test 6.

Test 6: Humidity Spot-Check Purpose: Humidity is essential for Calathea happiness. They like damp air, not bone-dry rooms.

How to perform:

• If you have a hygrometer, place it near the plant. If not, gauge the environment: winter heating, air conditioning, and dry rooms equal low humidity.

Expected outcomes and actions:

• Outcome A: Humidity below 50%.
  • Next action: Increase humidity. Use a humidifier, place plants in a cluster, or set the pot on a pebble tray with water (make sure the pot isn’t sitting in water). Misting is a quick fix but not a long-term solution.
  • Personal note: In a dry apartment, a small tabletop humidifier made a bigger difference than I expected. The curling decreased within days, and the leaves looked plumper again.
• Outcome B: Humidity above 50%.
  • Next action: Humidity is likely not the main issue. Move to Test 7 for a definitive root health check or a final environmental review.

Test 7: The Repot Tug (Last Resort) Purpose: This is invasive, but sometimes you need a direct view of roots to rule out root rot, compaction, or severe salt buildup.

How to perform:

• Gently tip the pot on its side and slide the plant out. Inspect the root system in the fresh soil.

Expected outcomes and actions:

• Outcome A: Brown, mushy roots with a foul smell.
  • Next action: Trim away all rotten roots with sterilized scissors. Repot into fresh, well-draining soil in a clean pot. Water sparingly for the first week after repotting as the plant recovers.
  • Insight: I once revived a Calathea whose roots were nearly black. It took careful pruning, a clean pot, and a gentle reintroduction to water, but the plant slowly regained vigor.
• Outcome B: Roots girdled, pot-bound, or soil extremely compacted.
  • Next action: Loosen the root ball and repot into a pot one size larger with fresh, airy soil. This also helps with heavy salt buildup if present.
• Outcome C: Roots healthy, white or tan and firm.
  • Next action: Replant in the same pot with fresh soil if soil degraded, or return to the pot if the issue is environmental rather than root-based. Reassess humidity, watering, and light.

Your Printable Calathea Leaf Curl Cheat Sheet To make diagnosis even easier, I’ve included a printable two-column cheat sheet that lists each test with its expected outcomes and actions. Keep it near your plants so you can walk through the steps in a minute or two when curling appears.

Why seven tests? Because curling is rarely a single issue. It’s usually a signal that moisture, light, pest pressure, and humidity are all interacting in your space. When you methodically test these variables, you’ll quickly narrow the problem down without turning your home into a lab.

A quick word on approach and pace: if you chase too many variables at once, you’ll misread symptoms. Do one test, observe the response, then move to the next. If a test clearly addresses the curling, you’ll see improvement within 24-48 hours in most cases.

The science behind leaf curling isn’t magic; it’s a plant’s survival mode. Calatheas’ leaves curl to reduce surface area and minimize water loss during stress. In the understory of tropical forests, that translates to needing steady humidity, consistent moisture, and protection from harsh light. When we recreate those conditions—albeit in a living room—our Calatheas reward us with lush, vibrant leaves and slower, more dramatic moves.

Real-world story: a weekend that felt chaotic, yet it produced a small breakthrough Two Saturdays ago, I found a curling Calathea on my kitchen sill. I’d overlooked water for a few days because I’d just watered another plant. The pot was heavier than expected, but not soaking wet. I did Test 1 first. It felt moderately heavy—so I skipped directly to Test 4 and realized the plant was in brighter indirect light than it could tolerate in late afternoon sun. I moved it a few feet back from the window and added a lightweight humidity tray under the pot. The curling eased within 24 hours. The micro-moment? The window that seemed “indirect” had actually been hitting the leaves with a late-afternoon shimmer; that tiny moment of sunlight is what tipped me off.

What to do next if curling persists If you go through the seven tests and the curling continues, you’re likely dealing with one of two stubborn issues: persistent under-watering or a chronic humidity problem. The fix is usually simple: more consistent moisture (without soggy soil) and increased humidity. If you’ve done all that and you still see curling, Test 7 (the Repot Tug) can reveal root rot or a root-bound pot. Once you confirm one issue, you’ll know whether to water more or to repot and re-evaluate soil structure and drainage.

A note on quality care and long-term optimism Calatheas aren’t “set it and forget it” plants. They like routine: water when the top of the soil feels just barely dry, provide consistent humidity, and keep them out of direct sun. The moment you shift any one of those levers, curling shows up as a warning signal. The seven-test approach respects this reality. It’s not flashy, but it’s how you build confidence and resilience in your plant care.

Two quick extras you’ll appreciate

• A two-column quick-diagnose cheat sheet you can print and keep by the plant stand. It maps each test to a specific outcome and a clear action. It’s saved me more times than I can count on busy days.
• A simple, no-fuss repot plan for when you have to dive into Test 7. Fresh soil, a pot just a size up, a quick root check, and you’re back in business.

If you want the cheat sheet and the printable steps, I’ve included a ready-to-download version at the end of the article. It’s a practical tool you can use every time curling reappears.

Closing thoughts Curling leaves aren’t a mystery you can’t solve. They’re a plant’s way of asking for a little adjustment—often a tiny one. The seven quick tests give you a practical, repeatable method to diagnose and fix the problem fast. If a test feels obvious, act on it. If a test doesn’t fit your space, move to the next one. The aim isn’t perfection; it’s a healthier Calathea that adds life to your home, day after day.

References ^[1]: FoliageFoundry. (2024). Calathea Plant Care Guide. Expert Care Resources. ^[2]: UC Davis IPM. (2021). Pests in Gardens and Landscapes: Spider Mites. Retrieved from https://ipm.ucanr.edu/PMG/PESTNOTES/pn7405.html ^[3]: Clemson Cooperative Extension. (2022). Houseplant Care: Watering. Retrieved from https://hgic.clemson.edu/factsheet/houseplant-care-watering/ ^[4]: Royal Horticultural Society. (2024). Calathea: Problems and Solutions. Retrieved from https://www.rhs.org.uk/plants/calathea/growing-guide ^[5]: Gardening Know How. (2023). Calathea Plant Care: Tips For Growing Calathea Plants. Retrieved from https://www.gardeningknowhow.com/houseplants/calathea/calathea-plant-care.htm

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References

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Footnotes

1. FoliageFoundry. (2024). Calathea Plant Care Guide. Expert Care Resources. ↩

2. UC Davis IPM. (2021). Pests in Gardens and Landscapes: Spider Mites. Retrieved from https://ipm.ucanr.edu/PMG/PESTNOTES/pn7405.html ↩

3. Clemson Cooperative Extension. (2022). Houseplant Care: Watering. Retrieved from https://hgic.clemson.edu/factsheet/houseplant-care-watering/ ↩

4. Royal Horticultural Society. (2024). Calathea: Problems and Solutions. Retrieved from https://www.rhs.org.uk/plants/calathea/growing-guide ↩

5. Gardening Know How. (2023). Calathea Plant Care: Tips For Growing Calathea Plants. Retrieved from https://www.gardeningknowhow.com/houseplants/calathea/calathea-plant-care.htm ↩