HPS Versus LED in Indoor Cannabis Cultivation

Current recently took part in a study that used the Arize Element L1000 fixtures in an indoor environment to gauge the effects of our PKR spectra on cannabis growth when combined in a checkerboard pattern with HPS. The dependent variables of the experiment were the dry and wet weights of the plants, and the independent variable was the type of lighting.

The Methodology

Two rooms were used for this study: Room A and Room B. There were 213 plants in each room, all identically placed.

Room A had Arize Element L1000, PKR spectra, installed in a checkerboard pattern with 1000W HPS fixtures. Room B was lit exclusively by 48 1000W HPS fixtures, for a total wattage of 48,000W. Room A clocked in roughly 21% lower at 38,000W.

In Trial #1, the harvest data that was collected and compared against one another included:

• Plant wet weight (grams) by room, strain and per plant level
• Plant dry batch weight (grams) by room, strain and per plant level
• Average dry weight per plant was calculated using the dry batch weight per strain and the number of plants per batch
• Wet weight and dry weight in grams per watt produced
• Percentages of THC and terpenes
• Microbial failures

In Trial #2, harvest data collected included:

• Individual plant weight in grams
• Total dry yield in grams for each strain
• Weight and dry weight in grams per watt produced
• Percentages of THC and terpenes

See the Results

In Trial #1, Room A (Current’s LED/HPS hybrid) significantly outperformed Room B (HPS only) in every observation category. It produced 25,450g more in total wet weight and an average 119g increase in wet weight per plant compared to Room B.

Room A produced 1,633g more in total dry weight and an average 8g increase in dry weight per plant compared to Room B. Additionally, Room A produced 2.4 g/watt more in wet weight and 0.38 g/watt more in dry weight than Room B.

Room A produced an average 3.5% increase in THC levels compared to Room B. There were no significant differences in microbial contamination (TVAB, TYM, BTGN, and Coliforms) observed between samples tested from each room.

In Trial #2, comparisons were limited by the differences in cannabis strains. However, like the results of Trial #1, the plants in Room A surpassed Room B in most of the categories. In terms of THC and Terpene profiles, Room A plants tested higher.

Additionally, Room A had higher wet and dry weights.

Current continues to investigate the impact of LED lighting on cannabis plant characteristics, quality and compound production. Our grow lights are also frequently used in research settings to study the effects lighting can have on vine plants, greens and other crops.

Follow us on Instagram (@gecurrent_daintree) for more from our horticulture team.