5 x 5 light set up

[Frank Cannon]

@Prawn Connery

Hello cob, yes I transplanted up all 4 and put them under my new strips at the same time - 20k lux, same environmental conditions and nutes for all 4.

Only 1 of 4 affected, 2 dif strains but its mate is pumping it. It was a little bit smaller than the others and I did think its roots were a bit too moist when potting up.

Yes 30/70 perlite to coco on light feeding schedule. Watering everyday now but remember I initially suspected over watering so I let it dry out for a couple of days then flushed with light nutes and calmag.
FC

 

[Prawn Connery]

Hi mate, I need to know what you're feeding them with.

As long as you have good drainage, you'll never have any problems with water retention in coco - certainly not with the 30% perlite stuff - so that could be the issue. If you have left them in standing water, then yes, that could be the problem and it will affect overall plant health.

Being the smallest plant indicates nutrient excess and lockout - not deficiency - especially if other plants of the same strain are bigger and healthier and not showing the same symptoms with the same level of nutrient.

You also dried out the pot for three days, which would have increased the salt concentration.

The lower leaves are all dark green - that signifies plenty of nitrogen (otherwise it would be yellowing from the bottom up).

The new growth is being affected - not so much the old growth - which indicates a problem with less mobile nutrients. So it's not a magnesium deficiency.

If you are feeding with flowering nutes, or anything high in K, there is a possibility it is locking out calcium. Coco release potassium as it biodegrades, so there is the risk of potassium toxicity and it looks like this:

Phosphorous toxicity looks similar (they both lock out the same metals):

If you test your pH runoff, excess K should register lower pH coming out than going in.

I'm not entirely sold on humidity being the issue - sorry Random - because I think drying out the pot would have been more detrimental, and all your other plants appear to be doing fine (plus evaporation from the pots will add to humidity inside your grow tent).

However, potassium toxicity is a very well-known issue in coco - especially if you are using flowering nutes all the way through. In a similar vein, many growers tend to overdo the phosphates, and this has a similar effect.

It is really hard to OD a pot plant on Ca - they can handle large amounts of calcium - so a Ca deficiency is much more common than toxicity.

Also, your plants don't use as much K in veg as NP, so it is more common at this stage and will clear up in flower.

This is going to sound counter-intuitive, but the trick in this situation is to feed at near full strength, but to water with a lot of runoff each watering so that excess K gets flushed out, but there is still plenty of NPCaMg etc in the mix.

Allowing pots to sit in runoff has the same effect as not flushing properly: the runoff evaporates in the tray and leaves salts to build up, which your plant then uptakes.

So, after you've told me what nutrients you're using, we'll come up with a mix and you can go ahead and water it through each day until your plant picks up again.

 

[Randomblame]

85f is max, probably closer to high 70s, but I haven't helped things by putting a 15" oscillating fan in there either now have I.

Looks like I need to buy a hygrometer !

So I have flushed heavily again with half strength nutes, and mixed up a foliar of a 4n1 essential additives- iron, nitrogen, cal and mag.

I'll remove the big fan, and let the collection tray keep 15mm of water in it to help increase humidity.

Strange why only one out of the 4 is affected! the other 3 are cranking it.

@Randomblame - for a gangster you're not too bad

Thankyou man
FC

Lol, yeah! Probably the most helpful gangster ever but the fu....s don't wanna hear it!

These little thingies work surprisingly well for me and you can find them as cheap as 2$ on ebay. I've ordered 2 5-packs with and without wired probe for the groom(3 spares) and 5 to put them in the weed jars.

One probe right on top of the canopy and the 2nd sensor just below the upper leaf layer.

But test them before using! One of 10pcs has shown 20% less humidity like the others, the rest works and shows pretty consistent results.
This is the e3ay part-number but I don't know if this offer is available on e3ay.au but the thermometer itself is for sure..
263359998514

 

[Randomblame]

Hi mate, I need to know what you're feeding them with.

As long as you have good drainage, you'll never have any problems with water retention in coco - certainly not with the 30% perlite stuff - so that could be the issue. If you have left them in standing water, then yes, that could be the problem and it will affect overall plant health.

Being the smallest plant indicates nutrient excess and lockout - not deficiency - especially if other plants of the same strain are bigger and healthier and not showing the same symptoms with the same level of nutrient.

You also dried out the pot for three days, which would have increased the salt concentration.

The lower leaves are all dark green - that signifies plenty of nitrogen (otherwise it would be yellowing from the bottom up).

The new growth is being affected - not so much the old growth - which indicates a problem with less mobile nutrients. So it's not a magnesium deficiency.

If you are feeding with flowering nutes, or anything high in K, there is a possibility it is locking out calcium. Coco release potassium as it biodegrades, so there is the risk of potassium toxicity and it looks like this:

Phosphorous toxicity looks similar (they both lock out the same metals):

If you test your pH runoff, excess K should register lower pH coming out than going in.

I'm not entirely sold on humidity being the issue - sorry Random - because I think drying out the pot would have been more detrimental, and all your other plants appear to be doing fine (plus evaporation from the pots will add to humidity inside your grow tent).

However, potassium toxicity is a very well-known issue in coco - especially if you are using flowering nutes all the way through. In a similar vein, many growers tend to overdo the phosphates, and this has a similar effect.

It is really hard to OD a pot plant on Ca - they can handle large amounts of calcium - so a Ca deficiency is much more common than toxicity.

Also, your plants don't use as much K in veg as NP, so it is more common at this stage and will clear up in flower.

This is going to sound counter-intuitive, but the trick in this situation is to feed at near full strength, but to water with a lot of runoff each watering so that excess K gets flushed out, but there is still plenty of NPCaMg etc in the mix.

Allowing pots to sit in runoff has the same effect as not flushing properly: the runoff evaporates in the tray and leaves salts to build up, which your plant then uptakes.

So, after you've told me what nutrients you're using, we'll come up with a mix and you can go ahead and water it through each day until your plant picks up again.

Hmm! I have always to deal with a too low humidity in my cab and have seen this symtomes many times. Most of the time its also strain dependent but can also be different from plant to plant. Especially if one is smaller or have had issues with excess nutes in the past. So it's probably caused by both, VPD and excess potassium and the high VPD has just accelerated the progress.
Most of the time the upper fan leaves show the first symptomes when the VPD is too high and even 80°F and 50% means ~1,7kpa and that's far to high for the current stage. So especially when he plan to feed near full strength he should increase the humidity at least by 10% otherwise it could get even more worse.

 

[Frank Cannon]

OK so I am following the Canna Veg light feed schedule, with a bit of Bio diesel Cal mag (high N), rhizotonic and cannazym. Run off pH is in the ball park, a little lowerr but it is also combined for all 4.

I am not also entirely convinced our gangster mate is correct either as the other 3 are smashing it, I am actually thinking it may have been a bit of root root as it may have sat in a bit of standing water considering how wet the roots were when I potted up. It has perked up a lot and is getting greener BUT I can see the tiniest bit of burn on the new growth tips as German Corleone mentioned about x Ca.

I just measured run off EC and it is off the scale, so I def have a salt build up already (fuck its been 1 week!, but real hot for night time temps i.e. during our normal day), which then points to a VPD issue cos they thirsty and drinking more water?

Random with the VPD is it more applicable to tent day or night or both?

I'm off to do a huge run off on dilute nutes with the culprit, then we can change it up tomoz depending on what you jokers think.

 

[Frank Cannon]

Right so they just been massively flushed with light nutes, I left the fan on Random so we could get some humidity up by evap of run off, nothing is sitting in run off.

The culprits run off is now only 200 EC higher than in and pH runoff is 0.2 lower than in (6.1 out)

So the bottom 2 are the same, the rest look ok in my new IT job

Here is a close up of new growth, tiniest burn't tips from X Ca? That's just water reflection on leaves.

Here is everyone tucked up back in bed

 

[Prawn Connery]

If it was VPD the plants would be sucking up nutrient as well as water. If your EC coming out is off the scale, and your pH is dropping, then your nutrient levels are too high and/or something else has caused the build-up (dehydration; not enough flushing etc).

Here's the Canna chart, how much of each are (were) you feeding? http://www.canna.com.au/node/2660

 

[Rocket Soul]

Right so they just been massively flushed with light nutes, I left the fan on Random so we could get some humidity up by evap of run off, nothing is sitting in run off.

The culprits run off is now only 200 EC higher than in and pH runoff is 0.2 lower than in (6.1 out)

So the bottom 2 are the same, the rest look ok in my new IT job
View attachment 4278015
Here is a close up of new growth, tiniest burn't tips from X Ca? That's just water reflection on leaves.
View attachment 4278019
Here is everyone tucked up back in bed
View attachment 4278020

They look a lot better. Your medium is still hot so not strange if you have slight tip burn. Damn, i really wished i would have caught that on those first pics as that is well within my somewhat short knowledge of plant nutes and their expressions. Oh well...

With your permission, hopefully, id like to ask @Randomblame a couple of questions regarding vpd as he is already schooling us a bit:
- is there a reason to adjust youre vpd according to medium? Looking at this from:
https://en.blumatshop.nl/blumat-tensiometer-soil
"The tensiometer is, as it were, an artificial plantroot that indicates the suction pressure in millibars. A high value, for example 200 mbar, indicates that the soil is dry. A low value, for example 50 mbar, indicates that the soil is wet. In the supplied manual you can see if your plant needs water. The higher the indicated number, the drier the soil is in the range of the roots and the thirst the plant has. Tub plants are best at a value between 80 and 120 mbar whereas plants in full soil feel best at a value between 150 and 250 mbar"
I understand this is the pressures of water in the medium, would you need a higher vpd for a medium that has a tendency to hold on to the water?
- you said the burnt tips is 100% excess calcium and gave a coherent explanation. This statement is based on the whole picture (tips burnt, but also showing deficiencies from lock out) or, can you actually see what nute is excessive by just looking at the tip. Or, can you see what differences in nute burn just looking at the tip?

I hope this doesnt derail anything, FC. Congrats on happier lookong planta

 

[Frank Cannon]

I was running running the 2nd level, have gone back to first line for flushing. I do tend to like feeding hard, I know I should relax, especially in summer as Mr VPD would recommend more dilute feeding at this stage also.
Oh and @Rocket Soul, this is my version of a Weedipedia thread, more than happy if someone asks an intelligent question, or in my case even a dumb question cos there is a tonne of good info here...enjoy, we are lucky to have the help we have
FC

 

[Or_Gro]

Hi mate, I need to know what you're feeding them with.

As long as you have good drainage, you'll never have any problems with water retention in coco - certainly not with the 30% perlite stuff - so that could be the issue. If you have left them in standing water, then yes, that could be the problem and it will affect overall plant health.

Being the smallest plant indicates nutrient excess and lockout - not deficiency - especially if other plants of the same strain are bigger and healthier and not showing the same symptoms with the same level of nutrient.

You also dried out the pot for three days, which would have increased the salt concentration.

The lower leaves are all dark green - that signifies plenty of nitrogen (otherwise it would be yellowing from the bottom up).

The new growth is being affected - not so much the old growth - which indicates a problem with less mobile nutrients. So it's not a magnesium deficiency.

If you are feeding with flowering nutes, or anything high in K, there is a possibility it is locking out calcium. Coco release potassium as it biodegrades, so there is the risk of potassium toxicity and it looks like this:

Phosphorous toxicity looks similar (they both lock out the same metals):

If you test your pH runoff, excess K should register lower pH coming out than going in.

I'm not entirely sold on humidity being the issue - sorry Random - because I think drying out the pot would have been more detrimental, and all your other plants appear to be doing fine (plus evaporation from the pots will add to humidity inside your grow tent).

However, potassium toxicity is a very well-known issue in coco - especially if you are using flowering nutes all the way through. In a similar vein, many growers tend to overdo the phosphates, and this has a similar effect.

It is really hard to OD a pot plant on Ca - they can handle large amounts of calcium - so a Ca deficiency is much more common than toxicity.

Also, your plants don't use as much K in veg as NP, so it is more common at this stage and will clear up in flower.

This is going to sound counter-intuitive, but the trick in this situation is to feed at near full strength, but to water with a lot of runoff each watering so that excess K gets flushed out, but there is still plenty of NPCaMg etc in the mix.

Allowing pots to sit in runoff has the same effect as not flushing properly: the runoff evaporates in the tray and leaves salts to build up, which your plant then uptakes.

So, after you've told me what nutrients you're using, we'll come up with a mix and you can go ahead and water it through each day until your plant picks up again.

Got a link to those nute pics, for common nutes?

 

[Or_Gro]

Gotta go with @Randomblame on the vpd contributor to excess nuteage....

Having a fucktime getting rh up (even in current Oregon rainy season).

I always push nutes hard, but even lower than my normal levels are causing probs, at 40% rh. Had to drop both temps and dilute nutes to get by, still not optimal vpd....

 

[Or_Gro]

Right so they just been massively flushed with light nutes, I left the fan on Random so we could get some humidity up by evap of run off, nothing is sitting in run off.

The culprits run off is now only 200 EC higher than in and pH runoff is 0.2 lower than in (6.1 out)

So the bottom 2 are the same, the rest look ok in my new IT job
View attachment 4278015
Here is a close up of new growth, tiniest burn't tips from X Ca? That's just water reflection on leaves.
View attachment 4278019
Here is everyone tucked up back in bed
View attachment 4278020

F’in nice wind tunnel dude!

 

[Or_Gro]

If it was VPD the plants would be sucking up nutrient as well as water. If your EC coming out is off the scale, and your pH is dropping, then your nutrient levels are too high and/or something else has caused the build-up (dehydration; not enough flushing etc).

Here's the Canna chart, how much of each are (were) you feeding? http://www.canna.com.au/node/2660

My plants selectively suck nutes during vpd stress...

 

[Prawn Connery]

Don't get me wrong - certainly there is a case for maintaining plants within their optimum humidity range - but I'm just not of the opinion it is the primary cause of nutrient lockout in FC's case.

Currently it is 32C (90F) outside and the RH is 26%. Look that up on your VPD chart. This plant has been growing in an Aussie summer with warm temps and low humidity without any signs of nutrient stress at all (burnt tips on some of the leaves are from the metal barbecue!).

For many years we've been growing indoors and out in Australia under similar conditions. Typical weather patterns see temps in the mid to high 30s (90-100F or more) and relative humidity usually peaks at dawn at around 70% or thereabouts, before falling during the day into the 20s and sometimes teens.

Australia is a hot, dry continent.

Yet plants grow fine. Even sativas, like the one above, which generally grow better in more humid conditions than indicas.

Grow rooms will tend to be more humid, as the heat coupled with all that moisture in the pots (especially coco, which should be moist pretty much all the time) raises humidity. But outdoors it's a different story.

The plant above has been in full sun and is only being fed nutrient every three days, with fresh water on other days. This is a different regime to my indoor plants, because the sun is a lot more intense than the LEDs and rapid evaporation (especially for such a small pot) is obviously an issue.

Again, the point is nutrient management. Plants can be grown in all kinds of conditions as long as you manage your nutrient levels for each condition.

Horses for courses.

I'm not saying VPD is without merit. I am saying that you can still manage your plants even if VPD and other conditions are not optimal.

 

[Prawn Connery]

Got a link to those nute pics, for common nutes?

Here you go: https://www.sensigarden.com/symptoms-problems/

I like this site, because it is one of the few that details both deficiency and excess.

FC's problem is pretty common in coco, and interestingly shows up much more in veg than flower.

Have a look at the video on this page - it's pretty cool - and note what is mentioned about potassium at about time 3.50: http://www.cannagardening.com/coco_a_b

 

[Prawn Connery]

I was running running the 2nd level, have gone back to first line for flushing. I do tend to like feeding hard, I know I should relax, especially in summer as Mr VPD would recommend more dilute feeding at this stage also.
Oh and @Rocket Soul, this is my version of a Weedipedia thread, more than happy if someone asks an intelligent question, or in my case even a dumb question cos there is a tonne of good info here...enjoy, we are lucky to have the help we have
FC

So what I was REALLY asking is how much (ml per litre) you are feeding of each. My interpretation of your answer (please correct if wrong) is:

A + B
2ml per litre

Rhizo
2ml per litre

Cannazyme
2.5ml per litre

CalMag
1ml per litre

That's 9.5ml per litre. Full strength A + B (according to Canna) is 8ml per litre (or, 4ml per litre of A + 4ml per litre of B)

In my opinion that is quite an aggressive feeding schedule - especially for a plant that has just been repotted and is under stress.

I also note that Canna A+B base nutrient is high in P (NPK ratio = 2.5 - 2 - 1.5). If your water is hard, and you are adding pH down in the form of phosphoric acid, that will also add P.

Canna actually warns about excess P in one of its info papers and suggests using nitric acid instead of phosphoric acid to lower pH for this reason if you have hard water and are using PK (potash) during flower.

It's also the reason why I posted images of both P and K excess, because - looking at your plant - I could go either way.

I'm also pretty sure Cannazym is an enzyme that breaks down and unlocks phosphorous, making it more available to the plant.

That's pretty much my take on things. The reason the other plants weren't as affected is because they were bigger, stronger and could handle more nutrient. Just looking at all those pants you can see how dark green they are, which indicates they are being fed close to their maximum.

The fact it is also hot and dry at the moment would exacerbate the situation (yes, VPD). I always run higher nutrient ratios in winter than in summer for that reason.

 

[Rocket Soul]

View attachment 4278493

Don't get me wrong - certainly there is a case for maintaining plants within their optimum humidity range - but I'm just not of the opinion it is the primary cause of nutrient lockout in FC's case.

Currently it is 32C (90F) outside and the RH is 26%. Look that up on your VPD chart. This plant has been growing in an Aussie summer with warm temps and low humidity without any signs of nutrient stress at all (burnt tips on some of the leaves are from the metal barbecue!).

For many years we've been growing indoors and out in Australia under similar conditions. Typical weather patterns see temps in the mid to high 30s (90-100F or more) and relative humidity usually peaks at dawn at around 70% or thereabouts, before falling during the day into the 20s and sometimes teens.

Australia is a hot, dry continent.

Yet plants grow fine. Even sativas, like the one above, which generally grow better in more humid conditions than indicas.

Grow rooms will tend to be more humid, as the heat coupled with all that moisture in the pots (especially coco, which should be moist pretty much all the time) raises humidity. But outdoors it's a different story.

The plant above has been in full sun and is only being fed nutrient every three days, with fresh water on other days. This is a different regime to my indoor plants, because the sun is a lot more intense than the LEDs and rapid evaporation (especially for such a small pot) is obviously an issue.

Again, the point is nutrient management. Plants can be grown in all kinds of conditions as long as you manage your nutrient levels for each condition.

Horses for courses.

I'm not saying VPD is without merit. I am saying that you can still manage your plants even if VPD and other conditions are not optimal.

I certainly agree with you on one point: one seems to be able to get away with a lot in an outdoors grow that would wreck an indoor grow. Could it be that the further we get from "natural" conditions (sun, soil with proper microlife, seasonal change and slightly randomly fluctuating weather) the more we have to micromanage our plants?

 

[Frank Cannon]

On the money Prawn, so what should I reduce to get closer to the first line ? A/B or rhizo / canna? Or just continue with all four at say a 30% reduction. My "dilute" flush was EC+ 1.

Do you use nitric as I haven't seen it in my travels?

I'm guessing you would recommend another good flush of dilute nutes. It has been hell hot for the last 10 days.....

 

[Randomblame]

They look a lot better. Your medium is still hot so not strange if you have slight tip burn. Damn, i really wished i would have caught that on those first pics as that is well within my somewhat short knowledge of plant nutes and their expressions. Oh well...

With your permission, hopefully, id like to ask @Randomblame a couple of questions regarding vpd as he is already schooling us a bit:
- is there a reason to adjust youre vpd according to medium? Looking at this from:
https://en.blumatshop.nl/blumat-tensiometer-soil
"The tensiometer is, as it were, an artificial plantroot that indicates the suction pressure in millibars. A high value, for example 200 mbar, indicates that the soil is dry. A low value, for example 50 mbar, indicates that the soil is wet. In the supplied manual you can see if your plant needs water. The higher the indicated number, the drier the soil is in the range of the roots and the thirst the plant has. Tub plants are best at a value between 80 and 120 mbar whereas plants in full soil feel best at a value between 150 and 250 mbar"
I understand this is the pressures of water in the medium, would you need a higher vpd for a medium that has a tendency to hold on to the water?
- you said the burnt tips is 100% excess calcium and gave a coherent explanation. This statement is based on the whole picture (tips burnt, but also showing deficiencies from lock out) or, can you actually see what nute is excessive by just looking at the tip. Or, can you see what differences in nute burn just looking at the tip?

I hope this doesnt derail anything, FC. Congrats on happier lookong planta

Like the humidity of the air influences the VPD so does the level of water in the soil affects the suction tension at the roots. Soil has shown that the best value for watering is between 50 and 80mbar. You water until you can read about 120-150mbar that stop and wait untill its down to ~80.
With Coco it is already different cuz there you feed several times a day and the optimal value is 100-120mbar all the time.

Plant symtomes can look very similar and often it depends on the situation. Without the VPD issues I would fully agree with PC and say potassium/salt build up but here it seems to me it's a combination of 3 different things.(VPD, overwatering and excess PK from salt build up).
When one things leaves the optimal range other things usually follow if you do not fix it.
So, yes it's possible to identify whats going wrong just by looking at the symptomes but you need to have the whole picture in mind. The link about nutrient isseus brother PC posted above is one of the best I've ever seen cuz it explains both deficits and excess and they use the whole plant to explain it not only a single leaf like usually.
I've already stored the link to have a closer look at it when I find the time. Best would be you download every single picture to have something like a plant symtomes encyclopedia.
But it explains only the symtomes but you need to have the whole picture in mind. VPD, temps, nutes, water, CO2 and of course the light.. all this has to be in a good range.
The problem with LED is it has no infra red radiation like the sun or hps. A plant outside in australia or elsewhere recieves a lot infra red when ambient temps are 32°C and the plant reduce transpiration to protect herself especially in such a small container. Leave stomata are mostly closed and the leaves are hanging for this reason.
With LED there is no infra red. The self regulation did not work properly for this reason. With hps I never had problems with the VPD, not even one time in 20 fu.... years!
I did not even know it was important, lol!

 

[Frank Cannon]

Double post sorry boys.