How to Tell If Your Cannabis Plant Is Getting Too Much Heat or Light

While cannabis plants love light and warmth, too much of either, whether from the sun or grow lights, can cause stress. Whether you’re growing indoors or outdoors, recognizing the signs of heat or light stress early can help you keep your plants healthy and productive.

What Heat Stress Looks Like

• Leaf Curling: One of the most common signs of heat stress is upward curling leaves, sometimes called “tacoing.” The edges curl up to reduce surface area and protect from intense light.
• Leaf Burn or Bleaching: If your leaves are turning pale, yellow, or crispy at the edges, especially near the top of the plant, your plant might be suffering from light or heat burn. This can happen when outdoor plants are exposed to intense afternoon sun or when indoor plants are placed too close to high-intensity grow lights without proper ventilation.
• Wilting Midday (Then Recovering): If your plant looks droopy or lifeless in the hottest part of the day but perks back up in the evening, it’s likely responding to heat stress.
• Brown Tips or Edges: This could also indicate that your plant is struggling to pull up enough water to keep up with the heat.

Tips to Protect Your Plants

• Move Containers or Use Shade
  For outdoor container grows, move your pots to an area that gets morning sun and partial afternoon shade. If you’re growing indoors, raise your lights or adjust their intensity to reduce exposure. For in-ground outdoor grows, use a shade cloth or garden umbrella during peak sun hours (typically 1–5 PM).
• Water Deeply and Early
  For outdoor grows, water in the early morning to help plants absorb moisture before the heat intensifies. Indoors, monitor humidity and consider watering near the beginning of the light cycle to align with plant activity and reduce evaporation.
• Mulch the Soil
  Adding a layer of mulch or straw helps retain soil moisture and keeps the root zone cooler. It also reduces how often you’ll need to water during a hot spell.
• Improve Airflow
  Good airflow helps regulate temperature and reduce the risk of mold. Space your plants out, prune if needed, and let the breeze move freely between them.
• Avoid Major Stressors
  Don’t transplant, heavily prune, or feed strong nutrients during extreme heat. Wait for milder weather to reduce overall stress.

Stay Ahead of Summer Stress

Cannabis can be surprisingly resilient, but catching heat stress early is key. With just a few small adjustments, you can help your plants thrive through the hottest weeks of the season, and set them up for a strong finish.

Want more growing tips tailored to your garden? Explore Seednest’s full collection of grow resources and outdoor-friendly strains here.