How to Grow Cannabis with LEDs

How to Grow Cannabis with LEDs

LEDs offer a very energy-efficient way of growing cannabis.

LEDs are one of the more practical innovations in indoor growing to hit the market in recent years. Not only do they consume less power (like… WAY less power), they reduce the risk of lightburn, save money on nutrients, and can be optimized to suit different phases of the growth cycle. But LEDs also come with a unique set of challenges and considerations. In fact, if you go into it blind, it can be easier to mess up with LEDs than with conventional lighting! So read up before you glow-up your grow-op – here’s a look at how to utilise LEDs with confidence.

#1 – Use Full-Spectrum LEDS

This is the first and most pressing consideration when you’re purchasing LEDs – getting the right lighting spectrum to keep your plants growing strong. Ideally you’ll want a lighting fixture that can easily switch between blue and white (for vegetating plants) and red (for flowering plants) spectrum lights.

#2 – Monitor Temperature Closely

LEDs don’t produce anywhere near the same amount of heat as conventional lighting like High Intensity Discharge (HID) or High Pressure Sodium (HPS). This means that your grow room and plants will stay much cooler, and you may have to invest in a more robust heater/temperature control mechanism. If you’re making the switch from conventional lighting to LEDs, make sure you monitor your plants closely for signs of stress.

#3 – Mind the Moisture

Less heat means less evaporation from the upper foliage, which in turn means less water is required to keep your plants hydrated. So avoid the pitfall of overwatering and hold off until you see early signs of dehydration, especially in the situation that you’re switching from HID or HPS lighting to LEDs. Remember, it’s always better to underwater than to overwater – the former can be easily corrected, while the latter can yield root rot that’s fatal to your garden. If in doubt, touch your finger to the topsoil. If it’s still moist, hold off on watering.

#4 – Keep em’ Close

LED light doesn’t travel as far as conventional lighting, and it can’t penetrate foliage to the same degree. This means that LED lights need to be kept much closer to the plants, and that more space should be left between plants to allow light to penetrate. Some growers use horizontal LED lighting along walls to supply the lower foliage with adequate lighting. But with that being said, don’t get them too too close – although less than HID and HPS, LED lighting is still prone to damaging leaves and flowers with light burn at very close proximities.

#5 – Lower Your Nutrient Load

Less water means fewer nutrients are flushed from the soil, and that means those nutrients will take longer to be fully absorbed. As we discussed in our greenhouse growing blog, too many nutrients is actually more harmful than malnourishment for cannabis plants, which means you’ll have to seriously lower your nutrient load and adapt to a new feeding schedule. Every case is different, but in general you’ll probably have to use 20-40% fewer nutrients, and might have to wait longer in between feedings. Experiment and find what works with your grow. (Added bonus – this saves you lots of money!)

#6 – Rotation, Rotation, Rotation

Because LEDs provide patchier lighting and don’t reach lower foliage anywhere near as much, it can be helpful to rotate your pots regularly to ensure that the lighting is even and that plants aren’t leaning too much. Some growers do this weekly, others biweekly or monthly – it’s all up to you and how your plants respond.

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