No stretch under LED

[yesum]

I am growing Panama Red(pure sativa) under LED 1st gen HGL, 2 62 watt units, 1 gal pots soil, 2x2' area. These have about 30% blue and white LEDs which is likely part of this problem. If I was doing sog or scrog this would be ok growth, but I want normal growth with the plants finished at 2 feet tall.

At 5 weeks veg there is one plant at 8 or 9 inches tall and thicker than the rest. The other 6 plants are 4 to 6 inches tall. I counted nodes and saw 6 on the shortest.

I moved the light over 2 feet off the tops of plants(it was at 1 foot) to help them stretch, but no sign so far after a few days. I also just switched to 18 hours on 6 off from 24 on, to maybe help stretch them.

I want these to be at least 8 inches tall at start of flower and a few are not close. I will be vegging 2 months for some of these to get to 8 inches, if they even do.

I am considering changing veg light next grow to 3000k pll and keep those well off the plant to get some height in veg. I already have a single pll that hangs vertically in center of grow for flowering, but is off during veg. Any ideas welcome.

 

[Sleepy]

2 x 62 watts is just barely enough to get them to stretch at all...

what are your temps like?

maybe increase temps and add some wattage until they are the height you want?

they will not stretch at all under LED.

 

[sm0k4]

LED is notorious for stunting new plants since people think they need to be 4 inches away from start to finish. Not the case. Young plants can't handle the energy being thrown at them in such strong concentrations. They will stunt or become bleached. Sounds like that isn't your problem though since you had it a foot away. Maybe a foot was too far and those LEDs aren't as strong, who knows. There has to be something else going on becuase I don't see the light causing your plants to not grow. Any nute issues or lockout that might have stunted them?

The veg stage is where LED beats any other light source. They must really make use of all the wavelengths that are now more intense with the LED array.

Also, not all LEDs are equal and ALL results will vary depending on how well the light is built and growing style. LED is too new so we don't have the exact formula of nutes and everything that we have now with HID. Its a whole new ballgame and there are different nute uptakes with LED because there is different light available to the plant that we don't normally have with HID. Mainly more reliable far red and far blue spectrums.

Other than that plants do seem to take up some extra nutes and require less frequent waterings.

To help with temps in winter, I have my intakes on the top of the back wall and my exhaust fan/scrubber on the bottom part of the opposite wall. This takes incoming air and moves it across my light, then down and out the exhaust. It gives my plants the light's radiant heat from the LEDs. Steady 78-80 degrees F in my cab for 30 hours straight during testing. I just threw my beans that popped into planters and am going to give LED a test go in my micro cab. I have ~30-35 Watts per square foot.

 

[yesum]

My temps average 78 so no prob there. I have them in ffof with added lime,bone and blood meal and perlite. I think 126 watts is fine for 2x2 area, I currently just have 1 63 watt unit running and have it over 2 feet off plants.

 

[VerdantGreen]

try bunching the plants closer together so the top leaves get most of the light and the ones underneath are shaded - then the plants should think they are in competition for light and stretch a bit. not sure why you want then taller though - a node is a node.

 

[GET MO]

I notice a lack of stretch vegging under led as well.
Makes me want to grow some pure sativas under um and see what it do.

 

[Shua1991]

A small 200w has would help alot in beefing up the plants, supplementing the leds.