Do fluorescent grow lights produce excessive heat?
Written by
Benjamin Miller
Reviewed by
Prof. Charles Hartman, Ph.D.Managing temperature continues to be a widespread issue for indoor growers using fluorescent grow lights. The amount of heat produced by these lighting systems is considerably lower than that produced by HID or LED systems. During use, surface temperatures typically do not exceed 95°F (35°C). This amount of heat will allow a fixture to be placed safely only inches from a plant. I've touched the bulbs of fluorescent grow lights while they were in use, of course, without burning my hand.
The minimal thermal output presents a gardening advantage that cannot be overstated. You can place the fixtures 2-3 inches above any tender seedlings without risking damage from the light. Leafy greens grow well inside without any signs of heat stress. The humidity in enclosed spaces stays constant. My indoor herbs do not exhibit any signs of tip burn, even at extended exposure times. This makes climate control much easier.
Plant Safety
- Zero leaf scorching at recommended distances
- No dehydration stress on young plants
- Eliminates need for heat shields
Energy Savings
- No cooling systems required
- Reduced electricity consumption
- Lower HVAC load in indoor spaces
Environmental Control
- Stable humidity maintenance
- Consistent temperature zones
- Prevents microclimate fluctuations
Utilizing the 30-second hand test will help you achieve perfect placement! Place your hand below the operating lights at the level of the canopy. If your hand is comfortable after 30 seconds, then your plants are comfortable. There is no guesswork involved in this simple approach. I teach this to all my gardening students. They don't suffer any heat damage using this method.
Fluorescent systems allow for no heat buildup, consistent performance; the use of electronic ballasts avoids any spikes in temperature for extended use; aluminum housings are designed for effective heat dissipation; tube styling was designed to optimize surface area for cooling; my fixtures stay on for up to 16 hours at a time and never exceed safe ranges. These consistent performance measurements enable continued plant growth cycles.
In terms of energy savings based on a reduced cooling demand, fluorescent lights also eliminate much of the expense associated with the ventilation systems required for safe HID use. The summer electricity bill is greatly reduced. Small, inexpensive fans typically supply sufficient air circulation. In fact, my energy costs decreased 30% with the switch from HID lighting. I have continued to save each year since then.
Read the full article: Fluorescent Grow Lights: Expert Guide
