Nov 23 2020 . 4 min read

Nov 2020: Home Grow 101

Nov 2020: Home Grow 101

A battle of the lights: HPS versus LED

A battle of the lights: HPS versus LED

By A.J., vegasbestbud

In past columns I have profiled home growers and the various methods they utilize in their grows. This month I wanted to deviate and share with you an experiment I have been conducting with the flowering process. Earlier this year I conducted a very interesting lighting experiment that pitted 600W High Pressure Sodium (HPS) against 480W Full Spectrum (UV & IR) LED (light-emitting diode).

I want to begin by briefly explaining the difference between MH, HPS and LED light fixtures. The conventional way of growing has always been to use a Metal Halide (MH) bulb for the vegetative stage. MH puts out a color temperature of approximately 6000K, which is great for growth. Then in the flowering stage growers switch to a High Pressure Sodium (HPS) bulb, which has a color temperature of approximately 2100K, great for flowering.

MH and HPS bulbs give off a lot of heat, which require air conditioning to stay cool. The LED I purchased has a color temperature of 4000K and it is dimmable from 0 - 100%. This LED runs much cooler, which will save on electricity and air conditioning. This light fixture is good from seed or clone in vegetation all the way through to the end of flowering.

Regarding life expectancy, MH and HPS bulbs are good for less than 10,000 hours of use or about one year and cost between $75 - $100 each. Most LEDs have a life expectancy of 50,000 hours of use. I spent $475 on my LED and bought a generic version of the HLG 550 V2 w/IR & UV. This fixture usually retails for about $900.

A quick note with regard to my growing history before I detail my experiment. Over the last 10 years I have been flowering cannabis plants with only a 600W cool tube in a

5’ x 5’ tent and two 600W cool tubes in a 5’ x 10’ tent.

In this lighting experiment I used clones from two different strains, Tart Pops and Strawberry Guava. I put two of each strain under each light. Everything except for the light source was the same. Both were in 4’ x 4’ tents, 5-gallon pots of coco and were fed house and garden nutrients.

Some immediate observations were that the plants in the HPS tent had stretched significantly more than their LED sisters whereas those plants were stronger and stockier.

As the weeks went by and the flowers matured, I began to notice the huge difference in smells (terpenes) and trichome production coming from the LED tent. Both strains in the LED tent were more colorful. When I touch the flowers in the HPS tent, they are much “drier” to the touch and not as sticky or stinky as the LED plants. The full spectrum LED brings out a lot more of what the plant has to offer.

After drying and curing the flowers, I personally will never use HPS again. The LED flowers are so much better in quality. Terpenes are significantly stronger to the nose than those from the HPS tent. Also, the taste was much more intense.

This side-by-side experiment has proven to me that small yields from LED lights are just a myth. Every plant in my LED tent yielded significantly more dried weight than the HPS plants. I won’t say this is true with all LED lights since they are not all the same.

As I write this article, my flower tent #1 is in week #8 of flowering. This is my second crop under LED lighting and it is just as good or better than the first one. If you are still using MH and HPS to grow your cannabis, you are missing out on flavors and smells you haven’t experienced yet.


If you have any questions about LED fixtures, growing, or garden setup, please drop AJ a message at Rookies123@aol.com or DM him at iG @vegasbestbud. AJ has an extensive collection of new and old cannabis genetics and consults on home gardens in the Las Vegas/Henderson area. He also gives free consultations and special discounts to veterans and medical patients.