3 weeks to go, what is happening

Hey there,

I’m growing some dr greenthumb OG Kush. 6 plants in 11l pots, watering every 4 days with 15l of nutrient solution. I get about a liter of runoff every time. I’m using the whole mills nutrient fertilizer line according to the feeding chart.

until about 3 weeks ago I cut my hard tap water with osmosis water in a 50/50 ratio, thinking I’m gonna do my plants something good.

Around the 26. Of April the plant started to show rust spots, wich I ignored at first, but later thought to be an calmag issue.

So for the last 4 waterings I added some low strength calmag and skipped the osmosis water.

Things are getting slightly worse by the day. Over night the yellow spots even appeared on one headbud.
Any idea what might be happening and how to stop it. My predicted harvest day ist the 27.05. Today I wanted to start using some ubv as a terpene booster. Will this damage/stress my plants even further?

Feeding them everyime? As i can see, lower leaves dont have this?

Maybe im wrong, but mybe too much feeding? Correct me..

Yes I feed the full strength every time I’m watering. Lower leaves are greener, but somewhat droopy.

Don’t wonder about the plant size, I tried a 8000k led in veg and early flower wich made them skip flower stretch entirely.

What medium are you using?

soil/peat Moss/coco?

you haven’t said.

Your feeding too much and in my opinion watering too much at a time. In 10/11 litre pots 800ml is where I top out ! I have some 10l pots and I water 600ml ! I water everyday when warm n dry, every other when cool and damp out. I feed every 3rd watering usually if watering everyday at 0.5ml a litre using mills and 1ml a litre if they need it, that's a and b by the way ! Find what works, I was gifted this mills and I'm not impressed with it ! Expensive as shit and I'd prefer biobizz in soil !!

Original StinkyG said:

Your feeding too much and in my opinion watering too much at a time. In 10/11 litre pots 800ml is where I top out ! I have some 10l pots and I water 600ml ! I water everyday when warm n dry, every other when cool and damp out. I feed every 3rd watering usually if watering everyday at 0.5ml a litre using mills and 1ml a litre if they need it, that's a and b by the way ! Find what works, I was gifted this mills and I'm not impressed with it ! Expensive as shit and I'd prefer biobizz in soil !!

Click to expand...

I only water if pots are light too ! If they are heavy I leave alone !

Player3 said:

Hey there,

I’m growing some dr greenthumb OG Kush. 6 plants in 11l pots, watering every 4 days with 15l of nutrient solution. I get about a liter of runoff every time. I’m using the whole mills nutrient fertilizer line according to the feeding chart.

until about 3 weeks ago I cut my hard tap water with osmosis water in a 50/50 ratio, thinking I’m gonna do my plants something good.

Around the 26. Of April the plant started to show rust spots, wich I ignored at first, but later thought to be an calmag issue.

So for the last 4 waterings I added some low strength calmag and skipped the osmosis water.

Things are getting slightly worse by the day. Over night the yellow spots even appeared on one headbud.
Any idea what might be happening and how to stop it. My predicted harvest day ist the 27.05. Today I wanted to start using some ubv as a terpene booster. Will this damage/stress my plants even further?

Click to expand...

I've noticed one or two of my plants which happen to be og kush, and a tiny bit on a critical og have the same issue ! Not as thorough as yours though, wonder if it's mills and og genetics ? Makes me wonder !

Original StinkyG said:

Your feeding too much and in my opinion watering too much at a time. In 10/11 litre pots 800ml is where I top out ! I have some 10l pots and I water 600ml ! I water everyday when warm n dry, every other when cool and damp out. I feed every 3rd watering usually if watering everyday at 0.5ml a litre using mills and 1ml a litre if they need it, that's a and b by the way ! Find what works, I was gifted this mills and I'm not impressed with it ! Expensive as shit and I'd prefer biobizz in soil !!

Click to expand...

This is where his medium choice needs to be known.

if OP is using coco then he’s not feeding with enough frequency and too high an EC.

Original StinkyG said:

Your feeding too much and in my opinion watering too much at a time. In 10/11 litre pots 800ml is where I top out ! I have some 10l pots and I water 600ml ! I water everyday when warm n dry, every other when cool and damp out. I feed every 3rd watering usually if watering everyday at 0.5ml a litre using mills and 1ml a litre if they need it, that's a and b by the way ! Find what works, I was gifted this mills and I'm not impressed with it ! Expensive as shit and I'd prefer biobizz in soil !!

Click to expand...

That’s how I did it before. I adapted this way of watering only since this grow. Read one of the millions of “cannabis watering 101” tutorials. I guess it was a bad one?

So you never have any runoff? I heard so manny stories about salt buildup when growing with mineral fertilizer that I thought this is a viable way of watering. This is my first non organic grow so I never had to care about runnoff. The Mills Set was a freebie from my local growshop so I thought I’ll give it a try. Was fine in veg, but from week 3 of flowering I was not satisfied anymore.

oh, and I’m growing in soil (50/50 mix of the light mixes from Mills and Plagron). How would you attack the problem now? Don’t give any more fertilizer until harvest (3 weeks)? Flush with plenty of tap water?

Player3 said:

Hey there,

I’m growing some dr greenthumb OG Kush. 6 plants in 11l pots, watering every 4 days with 15l of nutrient solution. I get about a liter of runoff every time. I’m using the whole mills nutrient fertilizer line according to the feeding chart.

until about 3 weeks ago I cut my hard tap water with osmosis water in a 50/50 ratio, thinking I’m gonna do my plants something good.

Around the 26. Of April the plant started to show rust spots, wich I ignored at first, but later thought to be an calmag issue.

So for the last 4 waterings I added some low strength calmag and skipped the osmosis water.

Things are getting slightly worse by the day. Over night the yellow spots even appeared on one headbud.
Any idea what might be happening and how to stop it. My predicted harvest day ist the 27.05. Today I wanted to start using some ubv as a terpene booster. Will this damage/stress my plants even further?

Click to expand...

mine started looking like that so i figured they were hungry so i fed them even more now they are half dead i also added cal mag and used ro water

osowhom said:

mine started looking like that so i figured they were hungry so i fed them even more now they are half dead i also added cal mag and used ro water

Click to expand...

Hope they will still turn out to have been worth the effort. I think I might have done the same if I didn’t ask here, the light leaves really look like there starving.

so should I just stop giving any more fertilizer and adopt a new watering schedule or should I flush them now and continue feed 1/4 strength (or flush and don’t feed)?

Hard tap water is going to have all the Ca and Mg you need. Too much of those can lockout other nutrients like P/K. I already said this in another post today but many people using calmag don't even need it. It seems like it's become the thing that people just assume they need. If you're growing in soil using tap water then chances are you don't need it. If your water is hard then it's almost a certainty you don't need it. That's why adding more calmag didn't solve anything and your issue is getting worse.

I'm convinced that many issues people have is a direct result of the overuse of calmag. And what's troubling is that's the first thing people add more of when anything goes wrong with their plants. It's not a cure all. It's 2 elements needed by the plant that are likely already available in adequate amounts. Not a post seems to go by that someones response to a grower having an issue is "Give it some calmag" when lack of calmag isn't the problem. It's like people are just programmed to reach for the calmag no matter what.

I just added cal-mag with the last few 3 or so feedings. The reason I did so were rust spots that were appearing on the leaves. I contributed that to me cutting my tap water with at least 50% of rear osmosis water every time for the entire grow.
I never did so before and never had to deal with those rust spots before. My thinking was: oh **** i just completely depleted my plants of calcium and magnesium - let’s get some back in there. I used atami wich should be dosed 0.1 - 1 ml/l according to the bottle. I went with about 0.2 ml/l. The spreading of the rust spots has stopped since, but now leaves start to wilt, yellow and crisp up

could it still be that my plants are suffering from a nutrient lockout? Or might there be another issue.


here some pictures of the rust spots wich appeared before the current issue.

Player3 said:

Hope they will still turn out to have been worth the effort. I think I might have done the same if I didn’t ask here, the light leaves really look like there starving.

so should I just stop giving any more fertilizer and adopt a new watering schedule or should I flush them now and continue feed 1/4 strength (or flush and don’t feed)?

Click to expand...

I wish I knew I am a newbie too mine will still harvest just not as healthy as I would like