Possible Magnesium Deficiency

Tried searching. No luck finding the exact same problem as mine.

I have 4 plants, 2 showing a few white patches, otherwise extremely healthy.

Using Fox Farn Ocean Forest soil. Grow Big, and Big Bloom fertilizers after 2 weeks.

Was nuting every watering. Found out it should be every other watering. Just started watering without nutes, so I can now do the every other watering suggested by Fox Farm.

The two plants effected are 4 and 6 weeks old. Using 400W MH and a 150W HPS.

My PH was a tad acid at 6.0 or so. Increasing to 6.5-7.0 with PH up. I haven't started that yet.

I was using tap water from a spicket that did not contain the water softener salt pellets that the rest of the home has.

I think I have narrowed down to:

Magnesium deficiency, or nute burn.

Reason for mag deficiency is perhaps PH too low, nute lockout of magnesium. Or, maybe the water is too hard.

I also have a cool air humidifier that was blowing a couple of feet away. Not sure if the mist could have something to do with it.

So, I'm going to use the water softener water, make sure the PH is 6.5-7.0, and use nutes every other watering now.

I have ruled out any kind of overwatering, as I only water every 3-4 days. Also, ruling out heat stress, because then temps are 68-76 degrees at all times. Ruled out any kind of bug, because I looked everywhere for them, under leaves and in soil.

Please help.

Self serving bump.

Any ideas?

Final bump. Is there anybody out there?

I feel bad nobody replied. Let me give this a shot.

Is this chlorosis/whitening of the leaf? Are there actual "burn" marks after it turns white? How close is your light? Could it be too much light?

Most likely not nute burn because the edges look decent. I also doubt it is Mg. Bring your pH down a bit and make some of the other nutrients available to your plant.

EDIT: Just noticed- the plants are 4 and 6 weeks old and are on ALL the nutes PLUS FFOF. The first few weeks of life FFOF is fine and probably too much by itself. dud you amend it with perlite or anything else? The stuff is good, too good for some strains and it burns them during the seedling and early stage of veg.

MendelMaster said:

I feel bad nobody replied. Let me give this a shot.

Is this chlorosis/whitening of the leaf? Are there actual "burn" marks after it turns white? How close is your light? Could it be too much light?

Most likely not nute burn because the edges look decent. I also doubt it is Mg. Bring your pH down a bit and make some of the other nutrients available to your plant.

EDIT: Just noticed- the plants are 4 and 6 weeks old and are on ALL the nutes PLUS FFOF. The first few weeks of life FFOF is fine and probably too much by itself. dud you amend it with perlite or anything else? The stuff is good, too good for some strains and it burns them during the seedling and early stage of veg.

Click to expand...

Thanks for responding and offering your help. This is my first grow, so I am very much learning.

Found out the runoff was 5.0 on the pH, ouch! Must have been locking out all the nutes and freaking my plants out. Flushed with 4 times the pot size with 8.0 pH to get to a respectible 6.4 runoff.

Will need to watch that. I believe I got too comfortable with the pH down without testing the runoff. A valuable lesson/experience.

The plants are already bouncing back big time. I believe I caught this early enough. Crossing fingers for no hermies.

When I flushed, I didn't add any nutes. I will go back to regular feeding on my next watering. I nuted too much anyway. Need to do the every other watering regimen instead of every time like I was doing.