@Krunchbubble is a San Franscisco-based medical cannabis grower with over twenty-three years of growing experience. Like many growers, @Krunchbubble was faced with determining the best strategy for optimizing yield and quality while reducing operational costs. Many cannabis growers rely on high-pressure sodium (HPS) lamps because of their ability to deliver adequate photosynthetically active radiation (PAR). Although HPS lamps can deliver high amounts of red light, they also produce large amounts of heat. HPS lights are about 25% efficient, meaning that about 25% of their electrical energy gets converted into light energy and the remainder into heat. This waste thermal energy is appreciated by some growers because they use it to heat their grow facility. However, this method of heating a grow facility is very inefficient and results in a high long-term costs. More recently, cannabis growers are starting to see the benefits of incorporating blue light into their growing spectrum. The spectrum from an HPS lamp is deficient in blue light, which is essential for optimal plant growth1. Furthermore, usually the significant thermal output from HPS lamps requires significant cooling to prevent the lamps from scorching plant tissues! @Krunchbubble approached URSA Lighting to discover the potential of LED technology for optimizing the yield and potency of their plants. In particular, @Krunchbubble wanted to know whether URSA’s LED lights could outperform standard high pressure sodium (HPS) light used in their facility.
“This technology comparison, between HPS and LED lights, demonstrates that LED lights are a viable alternative to the traditional HPS lamp. LEDs are a solution to enhancing the profitability and sustainability of the cannabis industry”
Ursa Lighting addressed this challenge by swapping out each of the old HPS lights for Helios 320 W luminaires. Typically, growers notice a number of benefits from switching from HPS to LED lighting. For example, LEDs emit narrow-spectrum light that can target specific photosynthetic pigments and maximize photosynthetic efficiency. Furthermore, LED lights are up to 90% efficient (depending on the spectrum), which makes them relatively cool compared to traditional HPS lamps. This allows LED luminaires to operate near plant tissues without causing heat stress. Since LEDs can be illuminated and run close to the plant canopy, greater PAR levels can be delivered to the plant’s leaves. The heat reductions gained when switching from HPS to LED have the added benefit of reducing HVAC and other operational costs.
|Old Lights||1000 W high pressure sodium|
|New Luminaires||Helios 320 W duet spectrum; Helios 185 W duet spectrum|
|Strain||Blue Dream, Chocolate Hashberry, Romulan Grapefruit|
|Plot Area||10’ x 10’ grow tent (100 square ft.)|
|Veg||4 weeks, 24 hr day length|
|Flower||10 weeks, 12 hr day length|
By switching from HPS lamps to the Helios 320 W LED luminaires, @Krunchbubble’s yields increased by 9%. In fact, each plot produced more than 3 lbs! In addition to yield increases, potency (THC content) increased by 3%. THC is produced in trichomes (small hairs) on the surface of the cannabis flower, and light quality can increase both trichome number and size. With more and larger trichomes, a plant can produce higher amounts of THC. Additionally, the Helios 320W lights decreased stem internode length and reduced plant stretching. Reduced stretching is associated with increased stem strength as well as increased yields2,3. Light quality and quantity greatly influences the elongation of plant stems, flower stalks, and branching.
In addition to increasing yields, @Krunchbubble had decreased energy consumption using LED luminaires compared to HPS lamps. At @Krunchbubble’s facility, the energy consumption metrics indicated a savings of 13% compared to the traditional HPS lamps. This technology comparison between HPS and LED lights at the @Krunchbubble facility underscores the positive impact of LED lighting on cannabis growth and development. It also demonstrates that LED lights are a viable alternative to the traditional HPS lamp and is a solution to the goal of enhancing the profitability and sustainability of the cannabis industry.
- Gómez, C. et al. Comparison of intracanopy light-emitting diode towers and overhead high-pressure sodium lamps (…) Hort Technology 23, 93–98 (2013).
- Zheng, M. et al. Manipulation of lignin metabolism by plant densities and its relationship with lodging resistance in wheat. Sci. Rep. 7 (2017).
- Islam, M. A. et al. Grain Yield, Forage Yield, and Nutritive Value of Dual-Purpose Small Grains in the Central High Plains of the USA. Crop Manag. 12 (2013).