Help! What are the leaves saying on my Northern light auto?

I finally decided to grow a pair… and grow a pair.

Started fresh (again) after learning alot quickly with 3 previous sets of seedlings and improving my setup.

There seems to be some absolute grow wizards on here so PLEASE help im very keen to learn! Anything you have to add is greatly appreciated.

Im using;
Seeds: autoflower northern lights
Medium: canna coco pro, in 4L root nurse fabric pots.
Light: mars hydro led on 20/4 light cycle (draws 300w any ideas on height?)
Tent: 1.2m x 1.2m x 2m at 27°C w/ ocelating fan
My starting water has a EC of 138ųs/cm or 66ppm

Im have;
Canna a+b
Canna rhizotonic
Canna cal-mag
Ph / EC testers of course

Also got an ‘exhale co2’ bag in the shopping cart.(Opinions?)

Anyway, im 2 and a half weeks in with these girls and have got the best results ive had so far so dont fancy pulling these out!

They both have had the exact same light, feed environment ect;
This is one

Ran into a bit of nute burn but recovered well after flushing both (keeping both the same)

BUT the other…

She doesn’t seem anything near as happy, i notice pale yellowish leaves on old growth, curling leaves, dark and light green new leaf growth, yellow edges and dark/brown spots on old growth.

My question is, what are my plants leaves telling me? Ive looked online but it could be 1 of a 1000 things so ive come back here, to speak to some experienced growers!

what am i doing right? What can i improve? What am i doing wrong?
ANY help and ANY experienced eyes on my topic is greatly appreciated!


Also the feeds i gave consistented of 6L water and 2ml of canna A+B, 1/4 strength of what canna recommended.

What is your ph? At this stage you dont need to feed them anything just regular ph water. Also you might be over watering them as well


@jwood ph of my flush was 6.5, this may of caused some over watering but couldn’t bare see them burning, what would you recommend as of water and nutes at this point?

That’s too high for coco. You need to be between
5.5 - 6 (ideally 5.8)
Plants look hungry. At this stage I’m usually feeding at about 150-250 ppm so about quarter strength . Forget the exhale bags. Co2 is only good for sealed rooms with insane amount of light saturation. Standard air exchanging will get your plants the co2 they need.
Lose the soil meter . They aren’t accurate if your using to measure ph. Invest in a good digital ph pen and a tds pen


I would guess a combination of PH off and over watering. Those plants need correctly PH’d water only after drying out thoroughly. Having them in large pots now makes flushing almost impossible. You can do it but the plant can drown waiting to dry out.

The meter you have shoved into the pot hopefully is NOT the PH and TDS meter you are using as they are essentially worthless. You need a decent PH meter and calibration solution to properly feed in coco.

These are a waste of money. Unless running high PPF lights in a closed system and high partial pressures, it’s not worth doing.


My first feed was measured with a digital ph and tds pen at about 6.5ph and 200ppm, the soil meter was just free with the mars light and used to check moisture, looks like ive overwatered and had a higher ph than 5.8 as @Watt-Sun mentioned.

@Myfriendis410 In terms of air exchange what would i need to set up my tent? At the minute its just a sealed zipped up tent, Its something i was hoping not to bite into and use co2 bags as a work around, as i cant get a good enough understanding on how to do it effectively and discreetly enough. I was concerned would bring down my temperatures in the tent also.

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CO2 bags just won’t generate enough to be helpful. It’s actually a highly technical grow with some danger associated with it. You need a sealed, climate-controlled space, a high pressure bottle of CO2 and a regulator putting out something like 1,400 ppm with associated monitoring equipment and that’s after you have ULTRA high intensity lighting to take advantage of.

All of that said; my last plant was grown in a 7 gallon fabric pot of Promix HP and General Hydroponics nutes with a yield of 14 oz in 4 1/2 months (402 grams IIRC) and my current plant is in a 2 X 4 DWC grow and going for a pound. So my question is; how much do you want to grow???


I would say i want to have 3 or 4 plants in my 1.2x1.2x2m tent, in terms of yields, maximum would be nice, i am more concerned about learning how and getting them fully through all stages of growth as healthy as possible, im not looking to go extreme now, but dont mind increasing budgets for a decent set up that will allow for big yields in future and save me an upgrade.

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You could cram 4 plants in there but 3 would be better IMO. The problem is that new growers don’t even know the right questions to ask and that can make for some frustration instead of enjoying it.

I keep telling folks to find a mentor and listen to that one person until experienced.

1/2 pound per plant is very doable and the metric for a happy grow is a big yield.


Plants drown in soil not coco. Coco can hold up to 21% oxygen even fully saturated. But by the looks of it too much water. Let them got a day with out water. And if you want to accelerate this put a seedling heat mat under the plants pot and it will grow crazy fast and dry faster.

What about your environment? What’s the humidity and temperature?
Ditch the soil meter. Huge waste of energy but a common retail ploy for new growers. (My family owns a hydro store so I know all about the nasty tricks.)
When you water how much runoff are you getting? At this point, in pots that big and plants that small, assuming that your humidity and temp are correct you shouldn’t need to water more than twice a week, if that.
And I forget who said it earlier, but they were definitely correct when they said that 6.5 is far too high for coco runoff. What’s your pH going in?
What’s the ppm of your water before you add nutes?
And yes, I absolutely agree that they’re a bit young for nutes just yet. They don’t need much from us in the beginning. Like, at all.

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Thats exactly why ive came here, hard to find anyone who actually knows what there doing (and isnt a liability) local to me!

My environment its a tent, in a spare room with 1 window. Ive no extraction or ventilation as not sure what i need. Humidity is between 60 and 80% and temp lights on 26-29°c and more like 20-22 off.
Ive a fan circulating air and keeping heat from the light uniform.

Going in my ph was about 6.5 i think, too high, as said, i need to aim for 5.8.

In terms of starting water its just 66ppm tap water, i have calmag but also been told not to use, no explanation. What would an over dosage be?

Im thinking do they need small amounts of ph’ water with come calmag and rhizotonic cannas rooting product? I can never seem to get it right, my last set seemed starved of nutrients after the 2 week point so i went onto feed from water (and burnt them with to strong a dose in hindsight)

Since the flush this is how they have developed, one good one bad, despite same conditions…as usual.

The ‘good’ one:

Sombody said ‘why are they so close to the soil?’ What does everyone think about this? Ive had so many stretchy seedlings before the new light i thought this was good?

Also are the leaves looking drooped or okay at this point?
What should me next actions be to give these the best chance they can?

First put a dome over them. Humidity in the 80 to 90% is good now. Properly PH’d water that has been left to dissipate chlorine is fine but you do need to let it stand for 24 hours or run an air stone in the water. If treated with chloramines you will need a deionizing filter to remove it.

I haven’t use the cannatonic line: I’m in GH. It is very important to be in correct PH range for your substrate (in this coco) which I actually prefer (for me) at 6.0. Your input TDS ought to be in the 300 ppm (500 scale) about now and gradually ramping up to peak of 700 ppm or so. Flower will be higher numbers but that should be good for you.

Who told you not use cal+mag? There a fucking moron. Cal+mag is a huge problem in coco. Coco steals cal+mag you have to use it. I use it every time i water. I can burn through 500grams in 3 months.
Make a light cal+mag folier and spray the leaves first and then add to the coco at 20g per gallon or as needed. The folier will bring them back fast.

Okay thanks for all the advice, im making headway now, heres an update…

Ive left the coco to dry out until the first inch deep was bone dry, during this period the poorer of the too plants i left as an experiment really (i was going to pull her out) has decided shes definitely not happy. What should i learn from her?

The other had not changed to much despite the drying out medium and was still very droopy.

I mixed a feed at 5.8ph, 40ml per litre of rhizotonic root and then topped up the ppm to 300ppm from about 100ppm using cal-mag. I used a fishtank oxygenation pump for 24hrs in the water.

I fed my plants about 3 L each, no run off, maybe a drip from each pot.

Plants reaction time! They responded well to the watering! The leafs are actually pointing up at the lights for once!
Heres some pics

When should i start using my A and B base nutrients?
Im now 3 and a half weeks in from them sprouting, what should i i expect to see next, or shall i just start fresh with the knowledge?
Ive new green gelato auto seeds on there way from royal queen.

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My honest opinion is, I would start fresh. Those poor babies are so stunted, you will be lucky if you end up with a quarter from each

Looks to me like they need nitrogen.

Week 11 now, Northern lights auto.
Is it time to flush?
My plant seems to have matured at different rates, ive noticed slight yellowing on the top colas fan leaves and more orange hairs there also,
I have more colas that seem to be nearly all white hairs though… ive attached all the pictures i can

Had great advice last time! if need any more pics just ask, thanks!