4k is making my plants look like crap

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DaFreak

Well-Known Member
So I've noticed that whenever I have plants under 4000k LED lights that they start looking really bad within a week, yellowing and looking like classic cal-mag problems. I'm using Lucas and even a little cal-mag so that shouldn't be a problem. Same plants will bounce back and start to green up almost within days under t5s or 3500k LEDs. I've noticed this same problem with 2 different bulbs that both happen to be 4k, once with t5 replacement led tubes and with high quality COB lights at 4000k.

Has anybody else noticed this? I have so many lights hanging around that I just swapped the lights out instead of really dealing with the problem but since I did buy some expensive 4000k LEDs I really should figure it out, also trying to lower my wattage hence why I bought the LEDs to begin with.

My answer is to stop using cal-mag at all, and add Epsom instead. It's just so odd that Lucas makes them look beautiful under anything but 4k.
 
hotrodharley

hotrodharley

Well-Known Member
DaFreak said:
So I've noticed that whenever I have plants under 4000k LED lights that they start looking really bad within a week, yellowing and looking like classic cal-mag problems. I'm using Lucas and even a little cal-mag so that shouldn't be a problem. Same plants will bounce back and start to green up almost within days under t5s or 3500k LEDs. I've noticed this same problem with 2 different bulbs that both happen to be 4k, once with t5 replacement led tubes and with high quality COB lights at 4000k.

Has anybody else noticed this? I have so many lights hanging around that I just swapped the lights out instead of really dealing with the problem but since I did buy some expensive 4000k LEDs I really should figure it out, also trying to lower my wattage hence why I bought the LEDs to begin with.

My answer is to stop using cal-mag at all, and add Epsom instead. It's just so odd that Lucas makes them look beautiful under anything but 4k.
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Personally I’d be cautious on cal mag using Lucas if you’re using the Micros and Bloom from a 3-part system. I’ve used Jungle Juice several years and found there’s usually enough of both until about weeks 4-5 in flower. Excess calcium inhibits uptake of other nutrients. I know this isn’t spectrum related but that’s been my experience.
 
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DaFreak

Well-Known Member
It's just a splash with veg Lucas. Normally I never used it but when I started with LEDs I was told that there was a mg problem and threw it in for insurance and it didn't seem to hurt, I haven't taken it out yet as they look awesome under my other temp cobs with it. But this is specifically a spectrum problem, seen it happen 3 times now.
 
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DaFreak

Well-Known Member
What are you feeding under the 4k? I've seen it happen 3 or 4 times with different 4k lights and then bounce right back under t5s. Same room so not an environment issue.
 
Star Dog

Star Dog

Well-Known Member
Is there any truth in plants needing more anything with different lights?
I've used from Cfl/T5s to hps and never noticed any difference in plant health, plant growth yes.
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My led experience (4k) is very limited again I didn't find any need for anything else?
 
D

DaFreak

Well-Known Member
Star Dog said:
Is there any truth in plants needing more anything with different lights?
I've used from Cfl/T5s to hps and never noticed any difference in plant health, plant growth yes.
View attachment 4852447
My led experience (4k) is very limited again I didn't find any need for anything else?
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I never noticed any change using the lights you mentioned either, but with LED 4k It's like night and day.
 
J

jonnynobody

Well-Known Member
DaFreak said:
So I've noticed that whenever I have plants under 4000k LED lights that they start looking really bad within a week, yellowing and looking like classic cal-mag problems. I'm using Lucas and even a little cal-mag so that shouldn't be a problem. Same plants will bounce back and start to green up almost within days under t5s or 3500k LEDs. I've noticed this same problem with 2 different bulbs that both happen to be 4k, once with t5 replacement led tubes and with high quality COB lights at 4000k.

Has anybody else noticed this? I have so many lights hanging around that I just swapped the lights out instead of really dealing with the problem but since I did buy some expensive 4000k LEDs I really should figure it out, also trying to lower my wattage hence why I bought the LEDs to begin with.

My answer is to stop using cal-mag at all, and add Epsom instead. It's just so odd that Lucas makes them look beautiful under anything but 4k.
Click to expand...
The only issue I had when I switched to LED were low temps (73-75) causing a lower uptake of fertilizer which caused a magnesium deficiency. Same strains in the tent next door under a 432w T5 at 80-81 exhibited no signs of deficiency using water from the same reservoir. Added an electric radiator and kept temps at 77-81. The problem went away and has never resurfaced.
 
Rurumo

Rurumo

Well-Known Member
I notice weird deficiencies pop up when I veg under a 100 watt led, then they disappear almost immediately when I put them under my main light, with no changes in nutrients. Stronger light=higher temps, more frequent feeding, and just better utilization of nutes. I think Johnny is right.
 
J

jonnynobody

Well-Known Member
Star Dog said:
Is there any truth in plants needing more anything with different lights?
I've used from Cfl/T5s to hps and never noticed any difference in plant health, plant growth yes.
View attachment 4852447
My led experience (4k) is very limited again I didn't find any need for anything else?
Click to expand...
No. The problem I see often is people switch to LED. Then their rooms are running much cooler. A problem they've never had before. They don't correct the environmental issue (i.e. cooler / less than ideal temps) and deficiencies develop. I watch people alter their fertilizer mix, blame their lights, and everything in between. Ask them what temperature their grow area is running at and the real culprit presents itself.

Colder temps slow down the plant's metabolism. Slower transpiration and slower nutrient uptake occur. Then a magnesium or calcium deficiency presents itself. Usually magnesium. Low temps are not a good thing. I have the best growth at 78-82F. Anything lower slows growth, transpiration, and nutrient uptake.
 
D

DaFreak

Well-Known Member
Room is heated to 72 outside of tents and with the COBs in the tent it's around 82. The lights are usually around 18 inches away which is their sweet spot. If I switch them to 3k COB same environment they bounce back, put them under the t5 outside of the tent with said 72 temp they bounce back. For these reasons I don't feel it's a temp issue. And actually they take up more water in the tent with the 4k COB then outside.
 
J

jonnynobody

Well-Known Member
DaFreak said:
Room is heated to 72 outside of tents and with the COBs in the tent it's around 82. The lights are usually around 18 inches away which is their sweet spot. If I switch them to 3k COB same environment they bounce back, put them under the t5 outside of the tent with said 72 temp they bounce back. For these reasons I don't feel it's a temp issue. And actually they take up more water in the tent with the 4k COB then outside.
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It could just be a light with a terrible spectrum negatively affecting your plants. I have ran low quality LED's where I experienced all sorts of leaf issues as soon as I flipped the bloom switch. Within 24 hours leaves were showing chlorosis and edges began frying within 2 days almost as if a calcium deficiency was occurring. I'm not sure what you're experiencing, but in my case it was just a cheap light poorly built with terrible components that produced a terrible spectrum. As soon as I removed those units and upgraded to nice quantum boards I've experienced none of those issues.
 
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