magnesium? rootbound? can't figure this one out

I keep getting this same problem first few weeks of flower most of the top leaves go yellow around the tips working its way in with brown spots throughout the middle then the curl up get crispy and die. I'm in sunshine mix#4 . they are about 6-8 week vegged under t5# then moved into 2gal under 1000watt hps to flower. Lights are about 2 ft away from the tops rooms 80 degrees and there's 2 fans circulating air in the room. I feed 1/4 to 1/2 strength GH flora series with calmag and straight water every other feeding. I thought overfeeding but I find that hard to believe at 1/4 strength I only water when dry and pH is always 6.5-6.9 so I'm running out of ideas now I'm thinking possibly rootbound but Im still too new to be 100% on anything. Any ideas ? I haven't really seen any pics this with leaf damage like this.

Sunshine mix#4 isn't that predominantly coco coir?

If so you should be pH'ing around 5.8-6.0

It looks like it could be an extremely late stage Mg def.

What % of Mg is in your nutes?

If sunshine#4 is coco then coco requires around 5%Ca and around 2% Mg during veg.

Then when in flower I like to up these levels from time to time to about 7%Ca and around 5%Mg.



J

Looks very much like Cal def.

vostok said:

Yes buds .....correct....note the yellow veins in the leaf thats the clue, sure has got some nute burn but a flush, 3 times the volume of the pot and a teaspoon of Calmag or Epson salts on the last rinse will do the plant well!

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I always get the late stage symptoms confused.

However Epsom salts is magnesium sulphate and won't help a Ca def.


And depending upon whether the Ca def is in fact a Ca def or could be an overdose on Mg causing symptoms of Ca def.


But I agree with you both.

Has to be Ca issues.

You can actually see the red spotting in the pic that buds linked on a background leaf.




J

Most plants need much more calcium and magnesium during the final weeks of flower than most growers provide, I've read scientific research that shows calcium being more important than phosphorus or potassium... On top of that, the chemical nature of calcium causes it to bond with iron sulfates, which "locks it out" basically disallowing the uptake of both "congealed" nutrients. This is especially known in hemophiliac people who must take extra iron supplements. They know to never mix their iron meds with any kind of calcium, even calcium carbonate which is what most antacids are comprised of. Ingestion of Ca and Fe in close proximity can cause nausea, stomach aches/pains, cramps, diarrhea, migraines, dysgeusia (an altered sense of taste, referring to metallic tastes), and many other symptoms. I would imagine that many of those same issues are present within the plant kingdom.
The long and short is, maybe your mixture of nutrients is off balance. Maybe your plant wants to use what you're throwing at it but it can't. Flush like vostok is saying then figure your imbalance...

I use Nectar for the Gods pro lineup, its a Cal based organic nute line up

Thanks for all the replies. Sunshine mix 4 is not coco its peat moss, perilite and lime. Can a cal def show up that bad over a few days?? I will flush and try to dial it in again but there's got to be something thats locking it out. Even though I let my tap water sit out 24 hours the ppm is over 200 could that have anything to do with it? With a soiless medium should I flush with plain water or 1/4 strength nutes or flush then 1/4 on the last rinse?
I've heard some contradicting statements about feeding with soiless medium some say to use plain water between nutes others say always use nutes what do you guys think ?

Water, nutes, water every 2-3 weeks flush with 1g to every gallon of soil

modene said:

Thanks for all the replies. Sunshine mix 4 is not coco its peat moss, perilite and lime. Can a cal def show up that bad over a few days?? I will flush and try to dial it in again but there's got to be something thats locking it out. Even though I let my tap water sit out 24 hours the ppm is over 200 could that have anything to do with it? With a soiless medium should I flush with plain water or 1/4 strength nutes or flush then 1/4 on the last rinse?
I've heard some contradicting statements about feeding with soiless medium some say to use plain water between nutes others say always use nutes what do you guys think ?

Click to expand...

I grow in coco and feed every time.

I monitor feed IN and compare it with runoff.

I very rarely/never use plain water.



J

jondamon said:

I grow in coco and feed every time.

I monitor feed IN and compare it with runoff.

I very rarely/never use plain water.



J

Click to expand...

I used to use coco ended up trying a mix of coco and sunshine now just use coco in veg for cloning and seedlings.