January 9, 2020
Too Much (or Too Little) of a Good Thing: How to Avoid Light Stress in Cannabis
Many growers prefer LED lights for their indoor grows, and for good reason. LEDs are much more energy efficient. They last a long time. They can provide full-spectrum light. And one of the biggest selling points is their low heat profile – meaning LEDs can get much closer to the plant canopy than other lighting technologies like HPS or fluorescents. This is an important benefit for many growers who are vertically racking or want ultimate uniformity and intensity for their crops.
However, misusing or being too zealous with your LED lights – even though they’re much gentler than other lights – can result in serious plant stress. There are many types of stress, but stress as a result of improper lighting can look like:
- Bleached buds. You might assume that albino buds are the result of some rare genetics, but really it is the plant reacting to light that is too intense. Bleaching can result in lower cannabinoid and terpene profiles – lowering the plant’s desirability.
- Wilted leaves. The foliage surrounding buds might look yellow, wilted and curled. This usually happens when plants are too hot (and they’re not getting enough water), so you’ll want to make sure your indoor temperature is closely regulated and there is proper ventilation.
- Prolonged vegetative state. Did you know cannabis is considered a short-day plant? This means it needs equal amounts darkness and light to trigger blooming. Leaving your lights on for too long after they’ve reached maturity can result in a prolonged vegetative state – not a good sign when you’re looking for ample flower production.
- Stretching. Lights that are hung too far away might result in plants that are long and spindly. Because they need the light for survival, plants grown indoors might reach up toward the light source that’s too far away. Worse, they could wither and die if they’re not receiving enough.
In order to prevent light stress, growers should:
- Hang lights at a proper distance. Hanging distance is a critical aspect of designing your grow facility. Lights shouldn’t be too far away from the canopy (resulting in stretching or unhealthy plants), but they also shouldn’t be too close, which can result in bleaching or heat stress.
- Gradually build intensity. Thrusting plants from a lower intensity “spring” to a full-fledged summer equinox can shock them. It’s like being woken up with headlights. Instead, gradually amp up the intensity to ease them into the bloom phase. LEDs make this easy with programmable settings that dim and brighten as needed.
- Keep temperature within an ideal range. Temperature is incredibly important to regulate at your indoor facility. Cannabis plants in the vegetative stage prefer 70 – 80 degrees, while blooming plants prefer cooler temps, anywhere between 65 – 75 degrees.
- Have a consistent light schedule. Cannabis plants are very sensitive to even the most minor changes in light. For the best results, LEDs can be programmed with a specific light-dark schedule. This prevents any human error or wasted energy and encourages healthy flower development.
Have questions about how to properly use your LED lights and get the most bang for your buck? Our knowledgeable team at ProGrowTech can help – shoot us a message here.