Top leaves turning yellow (pic)

mrcryce

Well-Known Member
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Anybody have an idea whats going on here? This leaf was pulled from the top canopy. Currently in week 8 of flower, using sunshine mix #4 soil. Any advice appreciated! Thanks.
 

redzi

Well-Known Member
I had a plant look like that when I increased the light around 3 times. You can buy a light meter (LUX meter LX1010B) for around $20 on Ebay...worth every cent. I found that I can double the light (lumens) but anything over that can get burned. The problem is that too much nitrogen can also produce a burn like that but its usually the lower leaves and if you increase N in low increments are get a build up the burn tends to be towards the tips of the leaves.
 

harris hawk

Well-Known Member
Stop using nutrients now and start flushing. Keep this in mind in relation to nutrient burn/toxicity is thast when you finally reconzie it you are all ready two weeks behind, use the back of hand to judge your light intensity from light to plant:clap:
 

mrcryce

Well-Known Member
I had a plant look like that when I increased the light around 3 times. You can buy a light meter (LUX meter LX1010B) for around $20 on Ebay...worth every cent. I found that I can double the light (lumens) but anything over that can get burned. The problem is that too much nitrogen can also produce a burn like that but its usually the lower leaves and if you increase N in low increments are get a build up the burn tends to be towards the tips of the leaves.
I suspected light burn as well but for some reason there are leaves higher than this one that are still completely green. Most of the leaves that look like this are on a shorter plant... Thanks for the tip about the meter though I will be looking into it. $20 is a steal for measuring something so important.
 

mrcryce

Well-Known Member
Stop using nutrients now and start flushing. Keep this in mind in relation to nutrient burn/toxicity is thast when you finally reconzie it you are all ready two weeks behind, use the back of hand to judge your light intensity from light to plant:clap:
What kind of toxicity am I looking at?
 

stickyflowers

New Member
What kind of plant man? Some are finishing up in week 8 so yellowing in areas could be normal as it finishes. If it is only on one plant though, and they are all getting the same thing, that one plant is just having a deficiency of prob cal/mag like topfuel29 says. Also, like harris hawk says, using your hand for feeling of heat is great way to tell what height you want the light to be at above your canopy. But to each their own brother.
 
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