Growing Cannabis with LED Lights - Pros and Cons

Lighting is a necessary part of any indoor grow operation but is often expensive and a pain to maintain. Many growers have started switching to LED lights because of their low energy usage. But are LED lights worth it? This article goes over some of the pros and cons of using LEDs.

LED lighting has been around for quite some time now, but has only really become popular in recent years. The technology has developed much further, allowing for huge improvements in many indoor grow rooms. Whereas before LEDs were inefficient and not worth their cost, now they have the power and efficiency to provide exactly what is needed for a cannabis garden to produce a top quality harvest.

What Are LED Grow Lights?

LED (light emitting diode) lights work with a microchip to send electrical current to different diodes in a series. When the current passes through the diode it illuminates and creates what we see as visible light. In LED grow technology, the diodes are emitting specific visible colours that are essential for healthy plant growth.

The spectrum emitted by an LED grow light is not always the same and varies depending on what the LED is designed for. For cannabis cultivation we only really need two different colours, blue for vegetation, and red for flowering.

There are some types of LED light that have a full colour spectrum which can be used for the whole life cycle of a cannabis plant. Although it is not essential to give a plant the full spectrum, adding more colours can improve the plant's understanding of its own environment because the LEDs emit a closer representation of sunlight.

Are LED Lights Better Than HID lamps?

HID (high intensity discharge) are the most commonly used types of grow light and they serve their purpose well. However, there are some drawbacks to using them, especially now we have newer technology developing at the forefront of the industry.

The main problem with HID lights is their high energy usage. Although HID lights are usually more efficient in the amount of lumens they provide per watt, there are other aspects to consider which make the overall efficiency better in an LED light.

LEDs do not use ballasts, which are needed in HID lighting to convert the electrical current into usable energy. This means they lose efficiency over time and eventually need to be replaced. LEDs do not need this extra equipment to do their job and can be plugged straight into the mains.

LEDs do not last forever but they have more than double the life span of HIDs. The filament in an HID lamp is very delicate and loses its intensity quite rapidly after use. HID bulbs are also broken easily if it not handled with care. Plus, HID lamps contain harmful elements like gases and mercury, making LED lights a much safer option overall.

Another factor that makes LEDs better is less wasted light. This is mainly because they can be placed closer to plants but also due to light being directed in a much more efficient manner. LED lights are already directed so they do not need a reflector like HIDs do.

HIDs run at very high temperatures and need cooling equipment to ventilate the hot air they produce.

In terms of yield and quality, LEDs are now as good if not better than HIDs. It all depends on the set up and how a garden is managed. LED grow lights have given growers the possibility to further fine tune the accuracy of their growing environment, so plants can now receive the exact light they need, exactly when they need it.

Tip: Having the extra warmth from HIDs can be useful if you are growing in colder climates.

Pros of Growing Cannabis with LED Lights

If you are planning to grow with LEDs, it is important to understand the pros and cons so you know if it is worth it for you. Unless you have a high budget, LED lights may not the best solution because the cheaper ones are often not on par with what they should be.

• They do not produce too much heat - Less equipment needed to maintain grow room conditions.

• Energy efficient - LEDs are almost 50% more efficient than HIDs.

• Direct light - Concentrated light dispersion so plants use photons more effectively.

• Environmentally friendly - Does not need replacing as often.

• Last longer - A good quality LED grow light lasts at least 50000 hours!

• Safe - Less heat/harmful materials, no breakable filament, and protected in housing.

Cons of Growing Cannabis with LED Lights

Although LEDs sound great there are a few drawbacks to consider before going ahead and buying them.

• LEDs are difficult to replace - if one LED breaks you may have to send the whole light back to the manufacturer.

• Expensive - we recommended choosing high quality to get the best results. Cheap LED grow lights are not worth it, often leaving you with small plants and low yields.

• Light can be too intense for plants - it is possible to burn your plants with light. Leaves can become discoloured or brown, curl and dry.

Blue Cheese First Grow

LED Light Grow Tips

Cannabis plants need around 30 - 50w per square foot of grow space. The amount of light plants need depends on which stage of growth they are at. This can be adjusted either through using dimmable LED lights or by simply moving lights closer to plants over time.

Seedlings - Seedlings should be introduced to the light gradually, especially if it is a high output LED light. An intense light can be a shock for a young seedling, so it is a good idea to start with your light about 50 - 60cm away from the tops of your plants and lower it 2 - 3cm per day. Set the light to vegging mode (blue) if it has one so the light can be closer to the plants.

Vegetation - If you notice plants stretching too much, think about lowering the light or increasing the intensity. This usually happens because plants are not receiving enough light. LED lights should be on for 18 - 24 hours per day and follow the same schedule as regular grow lights.

Flowering - Full spectrum LED exposure is recommended for the flowering phase. It is possible to only use red spectra LEDs but plants grow better with all colours available. Lights should be at their most intense by this stage so either move lights closer to plants or turn up the intensity to full. The closest distance lights can be from plants depends on the strength of the light.

LEDs should not be placed too close to the tops of your plants. Check the manufacturer information as LED lights vary in intensity. You may use the following table as a simple guide, but bear in mind that these are rough estimates that depend a lot on the quality of LED light you purchase. 

Conclusion

If you have been doubtful about LED lights then hopefully this article will have cleared things up for you. It is true that until recently, LEDs were not up to the same standard as HID lights in terms of their efficiency and productivity.

Finally LEDs have reached a level that makes them an affordable, viable option for home growers. There is so much to be learnt about LEDs, so share your thoughts with us in the comments section below!

External References

LED Lighting Affects The Composition And Biological Activity Of Cannabis Sativa Secondary Metabolites. Industrial Crops and Products. - Namdar, Dvory & Charuvi, Dana & Ajjampura, Vinayaka & Mazuz, Moran & Ion, Aurel & Kamara, Itzhak & Koltai, Hinanit. (2019) 

Basics of LEDs for Plant Cultivation. - Fujiwara, Kazuhiro. (2016)

This article was updated September 2020.