Bleached leaf from Blackstar LED (flower)

I get this a lot under 180w Blackstar flowering LED (not Hydro). It takes about 2 weeks to develop.. The veg lights are fine.

I don't think its Nutrient or pH problem, although it does look similar to Iron def. I've moved the lights further away but there's no heat, and the recommended distance is about 12"

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Any ideas other than bin the lights?

i had the same problem, turned out it was NPK deficiency from N overdose causing salt buildup & nute lockout.. when using LEDs you only need to water every 5-6 days.. dont judge it by putting your finger in the soil an inch or 2 but down about a 3rd of the pot.. i'm in a fairly cold climate so only have to water every 6-7 days.. It took me ages to figure it out but as soon as i let off the watering for a while, they soon recovered.. always make sure ph is 6.7 or 6.8.. p.s. when an LED beeches it makes the leaf go pure white.. not yellow 1st. Hope it all turns out well. I got a 240w blackstar flower 2012 from chrissies garden.

Thanks for that Equinox117, Im getting a better understanding of LEDs now.

I do try to keep the water down, but there is a temptation to over do it especially since they don't seem to need that much.

I'm getting the idea with soil grows its best to get feed sorted in the Veg stage & let them go.

Practice makes perfect... just wish it didn't take so long...

know exactly what u mean there.... i'm currently vegging under cfl & flowering under led... just switched a couple days ago... how far do u keep ur light from the plants?

Equinox117 said:

know exactly what u mean there.... i'm currently vegging under cfl & flowering under led... just switched a couple days ago... how far do u keep ur light from the plants?

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I have the Flower LED about 20 inches above the tops at the moment (the Veg LED about 9 inches). Plants on 12 hrs under both.. most of the original plants under the Flower LED have burned leaves, but I don't think its getting any worse... Maybe 20 inches inches may be a bit too far, but I wasn't sure whether that caused the bleaching or not.

The latest theory is that it is a deficiency so I'm going to feed cal/mag supplement to green them up a bit before I try the new ones under the Flower LED, by which time they will have had 4 weeks 12hrs under the Veg LED... A bit weird but it seems to work!

I have another plant under CFL that is very green, but then I changed the soil type & feeding with Seaweed.. That will go straight under the Flower LED in a couple of weeks...

Heres hoping...

nice dude, i hope 2 stay tuned... i've got my own strain on the go at the moment.. its called 'natural disaster'... it was an accidental cross of original amnesia & some bagseed that was pure sativa... cant wait i just lowered my led.. also flower model to 12 inches above my plants & no bleaching yet.. the watering is getting me a bit... i might try putting em in airing / boiler cupboard in night hours to dry em up a bit...

Cool, good luck with that... I think the plants are probably more vulnerable when they stretch after switch to 12hrs.. The speed they grow must put a strain on resources, compounded by the strong flower light. I've beentrying to get more complete feeding in veg, see what difference.

This is what happened to my LA Confidential from BS 240 veg/clone. I have not pinpointed it but its a combination of a few things for me because my pH was not calibrated correctly. For the first month all I used was canna rhizontic. This sends your ph of the roof. This stuff works great, but if you add 5ml to a gallon you will be at almost 8. The nute line im using will drop any water to 5.0-5.5. I was reading my george cervantes book and found this bit of information today. Chelates decompose rapidly in low levels of ultraviolet light. My nute line has a chelated calcium. I have a combination of things! I did a crazy flush today and have the lights about 16inches away. I have a new calibrated ph meter now. I added a 1/3 of the nutes with a pH of 6.2. I am going to give this a try and see what I come up with. All the plants are stunted now, but I want to turn it around and find a feeding that works. If things dont slow down or look any better I will try and add some Iron first.

I've had this happen with black star and spectra LED lights. I moved the lights up another 6 inches and the bleaching stopped, I left most of the bleached leaves on an was able to harvest with great results.

Having the same thing happen this time around but outside of the highest leaves bleaching again everything is looking great.

Im new at this but so far my harvest has been smaller with LED but I have never seen as many crystals on bud as what my LED lights produce. It looks like they were dipped in sugar crystals. HID=higher yeilding, LED= higher quality. I'm going to start doing a few head to heads and hybrid grows to find a way to get higher yields with higher quality.

johnnymcpotts said:

I've had this happen with black star and spectra LED lights. I moved the lights up another 6 inches and the bleaching stopped, I left most of the bleached leaves on an was able to harvest with great results.

Having the same thing happen this time around but outside of the highest leaves bleaching again everything is looking great.

Im new at this but so far my harvest has been smaller with LED but I have never seen as many crystals on bud as what my LED lights produce. It looks like they were dipped in sugar crystals. HID=higher yeilding, LED= higher quality. I'm going to start doing a few head to heads and hybrid grows to find a way to get higher yields with higher quality.

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Can I ask what your pH level was you were putting in? or do you check your soil pH?

I change up the ph a bit each time between 6.2-6.5

From what I understand nutes are absorbed at different rates based on ph. So I figure if I change it up a bit each time my girls should get a well rounded supply of nutes.

Im a new grower so I could be way off but I've had pretty good results so far

johnnymcpotts said:

I've had this happen with black star and spectra LED lights. I moved the lights up another 6 inches and the bleaching stopped, I left most of the bleached leaves on an was able to harvest with great results.

Having the same thing happen this time around but outside of the highest leaves bleaching again everything is looking great.

Im new at this but so far my harvest has been smaller with LED but I have never seen as many crystals on bud as what my LED lights produce. It looks like they were dipped in sugar crystals. HID=higher yeilding, LED= higher quality. I'm going to start doing a few head to heads and hybrid grows to find a way to get higher yields with higher quality.

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Think you might have a point there johnny



This is after 5 weeks in flower .. just wish it was a bit bigger.

I would like to know if you find anything out.

That looks like a nitrogen problem. Perhaps toxic build up or not enough nitrogen.