Improving Lighting - LED/HPS


Well-Known Member
Strain - Feminized Northern Lights, Feminized C99
# of Plants - 6 (3 of each strain)
Grow Type - Soiless
Grow Stage - Vegetative
Bucket Size - 3 Gallon
Lights - Veg: 104W 4100K Fluoro, Flower: 1x 300W LED, 150W HPS
Nutrients - General Hydroponics Flora Series
Medium - Soiless Mix (Homemade: ProMix, Pearlite, mushroom compost, with nutrient additives)
PPM - 770 at feeding (tap water is 340)
PH - 5.8 - 6.3
RH - 45% to 50%
Room Temperature -75 - 80F, constantly controlled
Solution Temperature -Room Temp
Room Square Footage - 4' x 8'
Pests - None Known

Hey all, I have a few questions on lighting. This is my first grow, and I'm growing a total of 6 plants. I powered through my veg issues, and I've been flowering for 1-2 weeks, depending on the plant. I moved 4 plants under my 300W LED (draws 185W) for the last 2-3 weeks of veg, and then flipped to flowering two weeks ago. The canopy was about 2.5' x 2.5', until I added two more plants and the 150W HPS. The LED was advertised to cover 2.5' x 2.5' during flowering. I noticed A LOT of stretch from the Northern Lights girls (they are the 3 tallest/largest ones). Some internodes were 4" long! Most of this happened during flowering, however, as all my nodes had a 1-2" spacing in veg. I've heard of some stretch, but is this normal?

I also understand my LED may be a little weak for these plants. I have another 150W HPS that I haven't added, but the one in there now is overheating my room as it is (plants are 80-85°F under HPS, 75-80°F under LED). What are your recommendations? Could I bring the HPS and LED to the same level, to increase coverage (and decrease intensity), and arrange the taller plants on the outside with shorter on the inside?

Instead would it be better to supplement some CFL's, purchase another LED (same type), or should I be OK as is, and rotate the plants every now and again? Remember, heat is an issue, and I'll probably have to remove the HPS soon.

The pictures make the LED lighting look very dark, but there is decent penetration (IMO), but still not as good as the HPS.



Re: Improving Lighting (LED/HPS)

The "Stretch" is normal for the first 3 weeks of flower. To control the stretch you can bring the lights down as close as possible without hurting plants, the LED should be closer, that will help with the stretch. 300w LED 16" from canopy if you see leaves or bud sites turn bleached white move the light up an inch until you stop seeing white bleached areas.

Next grow keep the temp only a couple of degree's different from lights on/off & lights as close as possible through veg into flower, as they stretch the first 3 weeks or so, you will be able to keep the internodal spacing close by raising the lights a little when you need. Also look into defoliating, LST, Super Cropping, to help control stretch, it helps with lateral branching.
Re: Improving Lighting (LED/HPS)

Plants stretch during the first 3 weeks of flower and they usually double in height, maybe even triple, after that I think they stop growing vertically. If you got the money I'd just get another LED, it will remove your heat issues for the most part and saves you money in the long run. Popping in a few CFL's never hurts either.
Thanks for the help guys! I knew that plants stretched in flowering, doubling or tripling in height, but I didn't know it was from the stem stretching! I assumed the plant continued growing throughout flowering, gaining height that way. I will lower the LED then, as I had maintained 24" during vegetation, and went for 18-20" in flowering.

As for the lighting issue, I went ahead and got another LED light. I'll swap it out for the HPS, and gain a little flowering room too!
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