Marijuana (Cannabis sativa) with Rolled Leaves: Diagnosis and Practical Solutions

Quick diagnosis

Likely Cannabis sativa L. showing mild stress signs: leaves rolled inward compatible with dehydration or environmental stress. No spots, necrosis, or visible presence of pests or diseases observed; color is uniformly green.

Most likely causes

• Insufficient or irregular watering that reduces leaf turgor.
• Dry air or low relative humidity (especially in winter in Tlaxcala).
• Cold or hot drafts causing transient stress.
• Substrate with inadequate drainage or compacted, preventing steady water uptake.

Immediate measures (what to do today)

Check substrate moisture

• Insert your finger 3–5 cm into the substrate. If it is dry at that depth, water.
• When watering, do so until water exits the drainage holes. Avoid small, repeated superficial waterings.

Humidity and environment adjustments

• If the air is very dry, moderately increase relative humidity (50–60%): place a tray with pebbles and water nearby or lightly mist the plants in the morning.
• Avoid keeping constant excess moisture that favors fungi.
• Protect the plant from direct heating or cold drafts.

Light and temperature

• Maintain bright indirect light; avoid abrupt changes in illumination.
• Recommended daytime temperatures: between 18 °C and 26 °C. Avoid nights that are too cold for the season in Tlaxcala.

Substrate and drainage

• Check that the mix is airy: for example, peat moss or coconut coir mixed with perlite.
• Ensure good drainage in the pot. If the substrate is very compact, superficially aerate the top layer without disturbing the roots.

Follow-up (7–14 days)

• Observe and note changes in rolling, vigor, and leaf color over one to two weeks.
• If leaves partially unroll and color remains green, continue with the new watering and humidity regimen.
• If yellowing, spots, necrosis or signs of pests appear (inspect or spray under leaves), document and consult for specific measures.

Observation checklist (7–14 days)

1. Are leaves less rolled?
2. Does green color retain intensity?
3. Is substrate moisture adequate at 3–5 cm?
4. Are there no spots or aphids/mites?
5. Is new growth normal?

Warning signs (act if they appear)

• Appearance of dark spots, necrosis or soft tissue.
• Generalized yellowing or premature leaf drop.
• Visible presence of insects (aphids, mites) or mold in the substrate.

Final recommendations

• Prioritize deep, less frequent watering rather than continuous superficial waterings.
• Maintain stable environmental conditions: moderate humidity and avoid drafts.
• Reassess the substrate if the problem persists: a more airy mix and good drainage usually correct absorption issues.
• Document changes and, if it worsens, take photos and consult for a more specific diagnosis.

With these measures the plant should recover turgor in days to weeks if the cause is water-related or environmental; the absence of spots or pests is a favorable sign.