Tips for Growing Cannabis Indoors During the Summer

Summer brings its own set of challenges for indoor cannabis growers. While outdoor conditions may seem favorable, the increased heat and humidity can negatively impact your indoor grow. If you already have a setup in place, these supplemental tips will help you maintain ideal conditions and avoid common summer pitfalls.

1. Control High Temperatures

Hot summer days can cause indoor temperatures to spike beyond what cannabis plants can handle. To manage the heat:

• Use an air conditioning unit or portable AC to keep temperatures between 70-85°F (21-29°C).

• Install intake and exhaust fans to bring in cooler air and expel hot, stale air.

• Run grow lights during nighttime hours when temperatures are naturally lower.

2. Manage Excess Humidity

High summer humidity can increase the risk of mold, mildew, and bud rot. Keep humidity in check by:

• Running a dehumidifier, especially during the flowering stage when moisture levels should stay below 50%.

• Monitoring humidity with a hygrometer and adjusting ventilation accordingly.

• Avoiding overwatering, which can contribute to high indoor moisture.

3. Optimize Lighting for Summer Conditions

Your lighting strategy may need a few adjustments to counteract summer heat:

• Switch to LED lights, which emit less heat compared to HPS or MH lights.

• Raise lights slightly higher to avoid burning the plants.

• Use light reflectors or Mylar to enhance efficiency without increasing wattage.

4. Adjust Watering Routines

Plants may drink more during hot weather, but be careful not to flood them. For effective hydration:

• Check soil moisture frequently and water when the top inch is dry.

• Water early in the day or after lights go off to minimize evaporation.

• Consider using drip irrigation or self-watering systems to deliver consistent moisture without overdoing it.

5. Strengthen Plants Against Heat Stress

Cannabis can suffer from heat stress in extreme conditions. Help your plants cope by:

• Adding kelp or seaweed extracts, which contain natural growth hormones and stress-relieving compounds.

• Supplementing with calcium and magnesium, essential for healthy cell function under stress.

• Applying foliar sprays early in the light cycle to boost resilience.

6. Maintain Proper Air Circulation and CO₂ Levels

Good airflow is especially important in summer. To ensure a steady supply of fresh air:

• Use oscillating fans and inline duct fans to keep air moving.

• Keep your grow room clean and uncluttered to promote even airflow.

• If sealed off, consider CO₂ supplementation to enhance plant growth and compensate for reduced ventilation.

7. Monitor for Pests and Diseases

Warm, humid conditions can attract pests and promote fungal growth. Stay on top of potential threats by:

• Inspecting plants daily for signs of mites, thrips, or mildew.

• Using natural deterrents like neem oil, predatory insects, or insecticidal soap.

• Rotating your preventive treatments to avoid pest resistance.

Final Thoughts

Indoor cannabis cultivation during summer requires close monitoring and proactive adjustments to heat, humidity, and airflow. With the right practices in place, you can maintain a stable environment and keep your plants healthy, vibrant, and productive. A little extra effort during the hotter months goes a long way toward ensuring a successful harvest.