New Grower First auto grow - question on led

[Bexter]

Am growing 3 nirvana northern lights autos, and they're one week old. Am using a 135w LED in a grow tent of 0.7 square metres - how close should the light be to the plants?

Very grateful for any advice.

 

[RollerofDoobs]

I'm using a blackstar 240w LED. I started my seedlings at 10''-12'' (about 25-30cm). Once they got their 3rd set of true leaves I raised it to 14"-16" (about 35-40cm). Depending on node spacing I may raise it a bit more, but I imagine no more than 18" (46cm) max.

 

[Bexter]

Cheers Roller. Any truth that if the LED is too close to the plants it'll bleach 'em?

 

[RollerofDoobs]

Sorry for the late response, been a little busy this weekend mate. I have only been using my blackstar for about 3 weeks now, no probs yet tho. I have heard of LED's bleach plants when they are too close, but as far as the Blackstar 240w's go, I know for sure seedlings can handle it at 10 inches with no problems. I believe new evidence is suggesting bleaching is cause by a cal/mag defficiency. I did hit my seedlings with a some MagiCal, but that wasnt untill day 12. Muddy, T-shirt, or Smashed might come through here and drop a little more knowledge on you. I think smashedbyhashish has had some first hand experience with LED bleaching.

 

[Taylorcarter]

@RollerofDoobs thanks

 

[Muddy]

The bleaching problems were mainly with the 2011 models from GrowLEDHydro. I'm running one of their 2010 models in one area, and two Blackstar 240s in another and haven't run into any issues. But do have some cal/mag on hand as plants grown under LEDs do seem to need more.

 

[Bexter]

Sorry for late reply myself and thanks to both for advice.

My 3 NLs are on day 14, so given them their first nutes, all Biobizz - Grow and Fishmix (1/4 strength), although have been giving them Root Juice for about a week too. They're looking quite good, although the older leaves were getting a bit pale, so decided to hit the nutes.

2 of them had quite spindly stems so decided to lower the LED. I just hope that a 135w (3 w) is gonna be enough to get them through - I've gotta small grow tent 40 x 40 x 120 cm (0.7 sqr metres). May upgrade to a 240w next year, if I need to.

 

[agito]

yon dont want to go more than a total 2ml per litre on grow and fish mix there both veg based fert with a high n ratio

 

[Bexter]

Cheers agito. Yeah saw that myself about both being high in n ratio.

:coffe:

 

[Hermitian]

Am growing 3 nirvana northern lights autos, and they're one week old. Am using a 135w LED in a grow tent of 0.7 square metres - how close should the light be to the plants?

For an LED system projecting on 0.7 square meters, you'll need a total of 290 W to 440 W at a height of 0.5 meter, or a total of 200W to 300W at a height of 1/4 meter. For more details, see the first post here: http://www.autoflower.org/f5/lumens-watts-why-should-you-care-3615.html