First Indoor Grow-GDP issues

Grand Daddy Purp Strain, photoperiod, ILGM Bank

-Age of plant: 4 weeks
-Method: FFOF/FFHF soil w/ perlite
-Vessels: 3 gallon smart pot
-Indoor or Outdoor: Indoor, 2x4 grow tent
-Light system: Mars Hydro TSW 2000. full spectrum led. set to 15% brightness
-Actual wattage draw of lights: draws 300W
-Current Light Schedule: 16/8
-Temps; 68-73F
-Humidity; 55-68%
-Ventilation system; None, minifan blows air out of tent
-AC, Humidifier, De-humidifier: none
-Co2: no
-PH: between 6-7
-no ppm meter or runoff measurements taken

Cannot figure out what is plaguing this plant. Thought it was P or K deficiency but I would think it’d be too early for that to occur. Began at lower leaves then worked its way up.
Noted on some older leaves that the stem is taking on reddish/purple hue.

I have scoured the internet and the plant troubleshooting guide ILGM posted and have found nothing definitive.

Please help, I do not want to lose this plant so early.


I just harvest a ILGM GDP Fem. You really should be checking your PPM in and out. What are you feeding her? Have you giving her any Cal-Mag? IMO looks like a Cal-Mag

here is a chart to compare to. Here is another chart Hope this helps. @Covertgrower @dbrn32 @MattyBear @BobbyDigital can you gentlemen help.

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Check your soil with the jeweler scope see if you got soil aphids that’s what they do to them i’m hoping it’s a Cal mag deficiency Soil aphids suck

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I would check your pH and PPM, but keep in mind that it is normal for a cannabis plant to lose the lower leaves as it matures.

The nodes look too far apart. I would increase the intensity of your light.


How are you measuring? Brand name, Amazon listing, or a photo of the device (or all three, why not?)

What nutrients are you using for her? If none, at 4 weeks you’re on schedule to be needing more

Last question is how are you watering and how frequently? How do you determine it is time to water?

Welcome and happy growing. :v:

here is a pic of the meter. i’m not sure of the precise model but i bought it off of amazon

I water based on the weight of the container. I just transplanted last week and then watered but haven’t needed to since then.

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haven’t used any nutes yet bc i just transplanted into final home a week ago so i was gonna give it another couple weeks

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That’s what I suspected with the PH range you were giving. I cannot stress enough how much your plants will thank you for investing in a PH pen. Apera or BlueLabs both make good quality testers. Apera has a $50 model but if it were me I’d spring the extra $25 for a higher end one - but I’m growing mostly hydroponically so PH will make or break my plants much faster. In soil you have a Ph buffer.

Anyway the reason I ask is if your Ph is way off, your plant will be locked out and will absorb nothing or next to nothing. Your soil may still have nutes in it (I don’t think so, or at least not enough anymore) but when the PH is way wrong, the plant can’t utilize it.

The 2-prong test meter is wildly inaccurate for measuring ph. If not simply entirely useless. It is good for moisture probing, to a degree

Edit: I just saw she’s got fresh soil from transplant. Leads me even stronger toward getting your Ph Fixed and supplementing with CalMag as someone suggested above.


ok thank you for the input. i had a feeling this soil meter was inaccurate. i will look into acquiring a pen. I was considering adding some cal mag to the soil.

My meter says ph is about 7.3 but idk if that should be taken at face value

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what should i be doing in the meantime to amend my soil? i have fox farms cal mag i can add but is there anything i should add for the pH.

Can we safely assume the pH is too high?

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@Graysin ^

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That’s too high by about .8 if it can be assumed even somewhat accurate.

Add this at a full strength dose.

A little bit but the problem is that anything to lower your ph will be quite strong. The only thing I can suggest is maybe a couple of drops of lemon juice in the water you feed with Cal Mag - and I mean like 2-3 drops. It’s a temporary PH adjuster but it will tell us if she starts eating/drinking again that the PH is in fact too high.

Thanks for tagging, it helps me see stuff :eyes:

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Thanks so much for the input man i’ll get on that right now

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@Graysin if i got a digital meter how would i measure the soil pH with it? i see them all advertised for water pH testing.

Would I have to mix the soil in distilled water then test that?

You can do a soil slurry - but the reality is the PH That matters is what you’re putting in. If you add 6.5ph every time to the water that goes in, it lowers (or raises) the soil ph over time to allow the plant to use nutrients again.

You can also test your plant’s water runoff from the watering - i.e. when you water, it should be enough that some comes out the drainage areas. You can measure that water from the drainage to see a rough idea of where the soil PH may be. It’s not the most accurate but it helps you see if you’re trending in the right direction for over all ph.


okay i got you. so it’s more of a gradual process that occurs over time

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Exactly. The watering with the right PH will have an instant impact but runoff will be weird for a while. :v:

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My opinion looks like the leaves touched the soil.


Lots of good feedback here that I would investigate on all fronts.

I also think you need to turn your light up. You may not have enough airflow through your tent either. And accurate ph and ppm measurements would help narrow this down significantly.


@Covertgrower if the leaves touched the soil why is it spreading up the plant? does that mean each affected leaf touched the soil?

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