Whether you're growing cannabis, hemp, or other crops in indoor grow rooms or greenhouses, maintaining the right temperature is crucial for optimal growth and production. Extreme temperatures—either too high or too low—can hinder photosynthesis, the process plants use to create food and fuel their growth. Ideally, air temperatures should range between 72° and 80°F. However, temperatures can go as high as 85°F when using CO₂ injection combined with supplemental lighting. For rooting clones, maintaining soil temperatures between 72° and 75°F is equally essential. The most precise way to manage these temperatures, especially in larger grow operations, is by using advanced environmental control systems. Below are five practical tips to help you achieve and maintain optimal temperature conditions:

Improve your environment with better and more accurate temperature control.

1. Ensure your HVAC system is properly sized. In indoor grow rooms, accurately sizing the HVAC system is essential to manage the heating and cooling demands that arise during plant cultivation. Maintaining precise air temperature, adequate air circulation, and effective dehumidification can be challenging, especially when maximizing plant density in each room. A properly sized system ensures optimal growing conditions and efficient operation.

2. Ensure adequate heating and cooling for your greenhouses. To maintain optimal conditions for greenhouse production, it’s essential to have sufficient heating capacity to handle winter temperatures effectively. Heating the area beneath the crops is more energy-efficient than heating the air above. Equally important is having reliable cooling capabilities for the summer months. Whether you rely on natural ventilation, fan-assisted ventilation, or a pad-and-fan system, make sure your setup can maintain the ideal growing temperatures, even during the hottest and sunniest days.

3. Install horizontal air flow (HAF) fans. Especially in indoor grow rooms, these fans are essential to help with air flow that helps distribute temperature more evenly throughout the crop and breaks up microclimates around all leaves for better gas exchanges, in addition to helping control powdery mildew. Try to avoid “dead air” zones (without airflow) within your rooms or greenhouse zones. Fans located too high above the crop do not provide enough air movement within the crop, but fans located too close to crops will adversely affect your ability to manage moisture levels.

4. Use shade curtains to protect your greenhouse during periods of intense sunlight and high temperatures. These curtains are designed to reduce light levels by 30% to 50%, effectively minimizing heat buildup. Keep them closed during the hottest and brightest times of the day for optimal results. If your greenhouse doesn’t have a retractable shade curtain, consider applying a whitewash coating to the roof as a temporary alternative. This coating mimics the shading effect and can be easily removed once cooler fall weather sets in.