E-mail -- LED vs HPS-2

Dr. Myers
What is the effectiveness of LED grow lights (such as the new Tri-Band type sold by HTGS) in comparison to HPS lights? Are there any reputable studies available for review showing these comparisons?
Thanks you in advance,

Hello,
Your question is a hot topic right now and one I can aswer from personal experience. I will be posting pictures of plants growing under LED in the next weeks.  Until recently, I never recommended LED lights b/c there was no proof they even grew plants.  When I started to do some research every study I read that was a scientific study (not done online by a grow store) said LED’s could grow plants, but they NEVER did so better than an HID. Most were not even close (50% less yield with LED). NASA has some studies online and I have read a few published articles from the USA and Japan. LED research is big in Japan I gather.
The new Tri-Bands from HTGsupply.com are indeed comparable to an HPS. The light frequencies of their LED’s are best for plants. I say this b/c all LED's use red and blue but not the exact color (wavelength) that is best for plants. Many grow stores make cheap red/blue LED’s to save money which means they are biologically not so great for plants. The trick/gimmick is that the colors your eyes see (red/blue) are not exactly the specific one’s that a plant uses ‘sees’.

LED as supplemental light: Last semester I used one 120 W. Tri Band LED in conjunction with a HPS and the plants under the LED looked real nice, and did not have the stretched stems that the plants next to them had (all HPS light). The LED allowed me to add several square feet to the area where I grew sun loving plants in my grow area. If you use an LED with other supplemental light sources (Sunlight, HID and/or Fluorescents) I know you will be happy.


LED’s Grow plants through whole life cycle: I have used the 120 watt triband and grown plants (basil, lettuce, Coleus and of course others) in a grow tent. I grew these plants from seed to flower with out any supplemental light and without a problem. While I did have success, the 120 w Tri-Band was not as effective as the 208 watt (4 bulb) T-5 HO that I did the comparison too.(Obviously, with that much difference in electricity usage the T-5 damn well better beat the LED)


I think though when you look at grow area square footage the wattages compares at about ½, meaning that a LED that is 120 watt is comparable to a 250 watt HPS… this is I admit in my humble opinion.  I have not measured lumens or photons per meter squared. I know HTGSupply.com did comparisons with light output etc. but I don’t use their data. This semester I am just eye balling plant growth so that I can at least give my opinion, in the past a few E-mails I have had to respond I don’t know about LED’s. I do know the Tri-Band from HTGsupply.com work great. I did a test with pictures if you want to see (LINKto LED test). Therefore I recommend, to replace a 400 w HPS two 120 w tribands and 3 tribands to replace a 600 w hps. This will cost you more but you’d still be way ahead in heat and wattage used per hour. Depending on where you grow and how long you will grow this may pay for itself in electrical usage in time.


If you are buying a light now, I always recommend an HPS as I know that you will be happy with the results. Exceptions are 1) if you are concerned with heat and 2) you are concerned with energy usage and 3) you are concerened about having to replace bulbs every year or two (which you should do with HID)  An LED does not put out nearly as much heat, or use as much electricity, so it will be your best bet in some situations.

Good Growing,

Dr. E.R.Myers