Nutrient burn? Deficiency?

My plants have been REAAAALLY healthy up until a few days ago when I started to see some yellowing leaves... this was after a feeding and I suspected nutrient burn, but I flushed and trimmed out the bad leaves yesterday and I'm still seeing a little more yellowing occurring. Is this residual from burning, or is this something all together different? Mostly occurring on low lying leaves around the perimeter, but some in the middle of the plant, too.

These are pics from right before the trim and flush:




Much thanks to anyone who can offer perspective on this.

I am thinking this is a cal/mag deficiency, from what I'm seeing in other threads. Can anyone confirm? I'll get on ordering a supplement asap...

got some pictures of the entire plant, and more details as to how you are growing this(timeframe, soil, lights, temps, humidity, watering frequency and how much, nutrients used, container size, etc, etc, etc)?

I haven't taken any shots of the whole plant WITH the yellow leaves, but the plants are a healthy dark green for the most part, with these random leaves dropping like flies going yellow. I will post up some shots of the plants just before they started yellowing... the plants look the same besides the random yellow leaves dropping.

Not seeing very much browning, which leans me more towards calcium def. than magnesium, based on the pictures I've seen.

Started from seed, vegged roughly 8 weeks? Lots of training so it took longer to get a decent height up.
FoxFarm Ocean Forest Blend with the standard regimen of FoxFarm liquid and dissolvable ferts, following the schedule almost to the letter.
Lights are T5 with custom PAR bulb setup. 8 bulb 48" setup.
Humidity seems reasonable but I am not monitoring it proactively... could this be too much humidity? Definitely doesn't seem like it's too dry in the grow area. I could get a hygrometer in there. I have pretty decent ventilation set up though, and haven't seen any signs of humidity issues so far. (the ones I'm familiar with anyway)
Watering when needed, about 500mL per plant (2-3 gal pots) --has been about once every 2-3 days, feeding every other watering.

Here's a canopy shot, not more than a week ago... shows the general health of the ladies I think... they look so good for the most part, then these leaves start dropping!

Is this a cal/mag issue? Magnesium browning usually appears more spotty from what I've seen... but calcium def. maybe?

This starts at the tip, yellows up, then browns from the tip and browns it's way up...

Dolomite lime is what you need.

FFOF seems to add enough to last ~6 weeks. They use oyster shell flour. Good stuff if they would put more in. I think they add just enough so it can be on the label. 8 week veg, you do the math.

A cal def is very likely and pretty soon, the mag and your pH will drop like a stone.

Good news is, the dolomite lime only cost ~$5 for a 40lb bag at Lowes. Once you use it, you'll never grow without adding it again.

Wet

Thanks for your help Wet... that sounds likely. Can I add oyster shell after deficiency? I have always been trained (mushroom history) to use natural forms of calcium like egg or oyster shell, because it is less likely to fuck up pH balance. Can I get away with sprinkling a bunch of crushed oyster on the top of the soil before watering? And if I use lime, how can I do it without harm? Mix into water first and pH balance the water before watering? How much lime do I need to add?

Would like to fix asap!! They seem to be stalling a little, but staying healthy. I am wondering if the pH is off already, since I'm not noticing growth.

In the future, would you recommend that I add lime up front, or maybe extra oyster shell up front? I was planning on doing a transplant of some clones today, so this information would be key!! I can get these ladies off to a solid start by buffering up front!

Wetdog said:

Dolomite lime is what you need.

A cal def is very likely and pretty soon, the mag and your pH will drop like a stone.

Click to expand...

Can you elaborate? I'm new to this... what is the relationship between calcium and magnesium that causes mag to drop when calcium is low? I'm going to hit the store shortly and look for lime or oyster shell or both...

Looking beyond the yellow leaves down low (normal at this stage), I see leaf tips curling under. You have a def brewing. Botanicare make CaMg+ in the correct ratios

I'm gonna be quick cause I need to make a beer run.

Dolomite lime is ground up dolomitic limestone and totally natural. It contains both Ca and mag. Garden or 'sweet' lime and oyster shell has pretty much 0 mag, but plenty of Ca.

For any of them, the finer the better. That's why the oyster shell FLOUR and powdered lime. Otherwise, you will be literally waiting years for it to break down and work.

Yes, it's best to add the lime up front. None of them really dissolve and need to be in contact or close proximity to the soil/mix to affect it.

BTW, the pelletized lime is just powdered lime formed into pellets with a quick dissolving binder, so that's ok to get also.

JUST NOT HYDRATED LIME!!!!! Or quick, or slaked, or burnt.

Add 2tbl/gallon of mix, or 1cup/cf of mix. Top dress is ok and water in. Don't bother adding it to the water, it will just sink to the bottom of the can.

Go get it and add to the mix and I'll try and do the technical stuff later.

Wet

Alright cool, I will find some dolimitic lime since it has the magnesium as well... much thanks!

Update: Picked up some good powdered lime, says it's got plenty of Ca and Mag. I poked holes into the soil surface with a screwdriver, then put a little under a tablespoon sprinkled across the top of each pot, then fed as usual.

I was worried about shifting the pH too drastically, so I only put about a tablespoon on each pot. (Each pot is about 2.5 gal)

Now that I compare that to the recommendation Wet made, it doesn't seem like much, so I'm definitely going to add more with next watering... at least this eases it in, which might prevent shock of some sort from the shift?

I hesitate to go all the way to 2tbsp:1gal with the top dress because it's going to sit on top... is that sound reasoning? I figured I'd add one more dose at next watering, maybe 2 tbsp per container... but to get to the 2tbsp:1gal ratio I'd have to add another 4-5 tbsp at least. Will it mess with the pH balance to have all that lime sitting on top, or does it all rinse down into the soil with the water pretty effectively?

I know that people feed CalMag liquid supplements with each feeding, but since this is solid and it will keep releasing, I assume I don't have to keep adding it once I've hit the target ratio...

So Wet, would you say that ratio still applies if it's a top dressing later in life, or should a more gentle approach be taken at that point since it can't be agitated throughout the medium by hand?

Hmm... stil significant amounts of yellow leaves today... will leaves that already went yellow recover or are they doomed?

hey wet, how many times have you posted the same response to us noobs using FFOF? I'm personally not gonna start thanking you till I see if it helps me out but im about 100% you're advice to me, to add lime, is correct .

Gonna add a bunch more lime today with watering. Hoping this does the trick!

Okay, hoping someone sees this... basically, I'm not entirely covinced that this is a deficiency at this point... is there any kind of endemic attack that can cause this appearance? This is a very young plant that has been in the garden with the big ones for a week or so, (12/12 from clone in a solo cup) and I am seeing the SAME leaf degradation that I am seeing on the rest of them.

Could this be some sort of mold or insect damage?

Pic:



I'm also wondering if this could simply be nitrogen deficiency all along? I am using Fox Farm and Big Bloom seems kind of light on the nitrogen... I'm wondering if the buds on the big plants are simply soaking it up faster than I can provide it with the normal feeding rate? This solo cupped 12/12 has not been transplanted since cloning and I am wondering if there just isn't enough soil in there to give it a decent boost of N... I haven't fed it yet, but I a going to try it today when feeding the others and see if that helps...

The very tips of the next couple leaves are also off, a TINY bit of yellow and brown on the tip of each leaf.

I guess it could even be the same issue and I need to add the lime to this as well?? It's only been flowering briefly but maybe it used up the limited resources of this small solo cup already. Should I transplant, or maybe just add more soil with some lime and feed with nutrients?

Okay, here's one of the big ladies... the damage seems more intermittently distributed on the leaves in this case... a little spotty, which made me think some sort of insect damage... but I have investigated the leaves closely with a 30x magnifier and there is nothing moving on them on either side. What is going on here? I would be very grateful if anyone can help me get ahold of this! I am SO close to finished and I would hate to see the crop die before that last burst of goodness.

And these are shots from two more new babies who are exhibiting what seem like the same traits to me, but maybe not...