Brown Spots Showed Up Today. Help Needed.

[JackD]

I'm growing in soil with 600w MH. About 4 to 6 weeks into veg.
I ph to 6.4 every time, using tap water that has been sitting for at least 24 hours.

I've been feeding with every watering (about every 3 days), but only using 1/4 tsp per 4 gallons of Jack's Classic instead of the 1/4 tsp per gallon they suggest.

This morning, I watered and fed with 1/2 tsp per 4 gallons.

Tonight, brown spots have suddenly shown up on 3 of my 8 plants. These spots were not there this morning.
The spots are on 2 of my 3 pineapple haze and 1 of my 3 blueberry.
My 2 Strawberry Kush look fine.
2 of my 3 blueberry's look fine.
1 of my 3 pineapple haze looks fine.

My first thought was nute burn from upping the amount, but the spots are in the middle of the leaves, not on the tips. And this is still only 1/2 the suggested dose.

Can anyone tell me if this is nute burn or something else going on?

 

[dnewsome2]

You might look into magnesium and iron.

 

[JackD]

From some of the pictures I've seen, it looks a little like a Calcium deficiency. But I'm not sure how likely that is when using tap water. And the timing of this happening right after I upped the dose of nutes makes me suspicious.

 

[stonestacker]

To me the light green of the plants in general says feed me more or not enough light. I don't think shit shows from one feeding that fast. Just my opinion no facts.

 

[BudBogart]

From some of the pictures I've seen, it looks a little like a Calcium deficiency. But I'm not sure how likely that is when using tap water. And the timing of this happening right after I upped the dose of nutes makes me suspicious.

I understand that the calcium found in tap water is structurally too big to be absorbed by the soil so it still might be calcium -.

 

[JackD]

To me the light green of the plants in general says feed me more or not enough light. I don't think shit shows from one feeding that fast. Just my opinion no facts.

I don't think light is a problem. They are about 18 inches below a 600w air cooled MH.
I agree about the color. I thought if it was too much nutes, they would be darker green. It just seemed odd that the spots weren't there a couple days ago and seemed to show up right after a feeding.

So I'm puzzled.

Any chance those spots could happen if I dripped some of my nute solution on the leaves when I was watering?

Or maybe I have a cal deficiency that was just starting and for some reason, the watering and feeding triggered it to get worse?
I don't have any CalMag because from what I had heard, it didn't seem that was usually needed using soil and tap water. But I can get some if you guys think that's worth a try. Or I can do nothing for a couple days and see if it gets better or worse.

 

[BudBogart]

I don't think light is a problem. They are about 18 inches below a 600w air cooled MH.
I agree about the color. I thought if it was too much nutes, they would be darker green. It just seemed odd that the spots weren't there a couple days ago and seemed to show up right after a feeding.

So I'm puzzled.

Any chance those spots could happen if I dripped some of my nute solution on the leaves when I was watering?

Or maybe I have a cal deficiency that was just starting and for some reason, the watering and feeding triggered it to get worse?
I don't have any CalMag because from what I had heard, it didn't seem that was usually needed using soil and tap water. But I can get some if you guys think that's worth a try. Or I can do nothing for a couple days and see if it gets better or worse.

Search "the charts" post by SeaMaiden. The will help identify what is going on.

 

[stonestacker]

I would up my feed and try 1/4 -1/2 strength calimagic.

 

[JackD]

This morning, it looks like 4 of the 8 plants are affected. The 2 Pineapple Haze are the worst and 2 of the Blueberry have just a couple leaves with these spots.

Here is a pic of all the plants

Here is the best looking plant. It's a Strawberry Kush

Here is the worst looking plant. It's a Pineapple Haze.

 

[JackD]

Search "the charts" post by SeaMaiden. The will help identify what is going on.

That charts post says Ca def should only show up on new upper leaves, but I'm getting the spots on some of the biggest upper leaves, not brand new growth. So I'm still puzzled. :)

 

[JackD]

Maybe Mg def?
Some of the leaves definitely look like the pictures here:
https://www.sensigarden.com/magnesium-deficiency-marijuana/

 

[stonestacker]

Those charts are hard for me to decipher they all look the same lol.

 

[Dunge]

You start right out telling us that you are using the additive at 1/4 suggested application rate.
My first though is that they are starving.
Necrosis like that takes several days to develop, so the insult may have taken place long ago.
Good luck, and you might back off on pH adjustments.

 

[JackD]

You start right out telling us that you are using the additive at 1/4 suggested application rate.
My first though is that they are starving.
Necrosis like that takes several days to develop, so the insult may have taken place long ago.
Good luck, and you might back off on pH adjustments.

It's my first grow and I've read so many warnings about common beginner mistakes like over feeding and over watering. So maybe I was overly cautious and didn't give them enough. But everything I've read has warned that you should use a lot less than the package says. Especially if you are using general all purpose ferts.

It just seems very odd that these spots would appear so suddenly and it would be right after I upped the amount of nutes. But maybe it's just coincidence. If it's a deficiency, maybe it's just because it's been long enough that the soil finally ran out of whatever nutes it started with.

I ordered some CalMag that should be here in a couple days.
In the meantime, I gave them some 6.5 water with 1/4 strength Jack's and a little epsom salts mixed in, in case it's Mg def. I'll see how they look tomorrow.

 

[Monster762]

I would up my feed and try 1/4 -1/2 strength calimagic.

Calimagic I agree.

 

[Leew421]

I would say you might be having a lock out. How much water/feed do you run?

 

[Leew421]

How do you mix the nutrients?

 

[JackD]

I've got 8 plants in 3 gallon pots, all sitting in an elevated 2' x 4' flood tray that is slightly higher on one side, with drain holes on the low side.
Fill a 5 gallon bucket with 4 gallons of tap water.
Let it sit at least 24 hours.
Add 1/4tsp of Jack's Classic All Purpose 20-20-20 (or 1/2 tsp the last time). The package says to use 1/2 tsp per gallon once a week or 1/4 tsp per gallon for every watering. So I've been going with 1/4 of the suggested amount for feeding with every watering. 1/4 tsp in 4 gallons of water.
Stir for several minutes.
Measure ph, add ph down as needed (tap is usually around 7.5 to 8) until it's ph around 6.4.
Water each plant until there is some run off.
I've been doing the above when the top inch of soil feels dry, which has been about once every 3 days lately.

 

[Leew421]

If you're in soil I would back off pH up and down

 

[JackD]

If you're in soil I would back off pH up and down

Can you explain why?
I'm new to this, but based on what I've read, I thought the ph should be between 6.2 and 6.8 for soil, and my tap water is at least 7.5. Won't using 7.5 water cause lockout problems?