can someone help me diagnose this issue?

[Catfish22]

It is a photo, correct? Either way it will be ok with no nutes for the couple days until it's time to water again.
Now you have clean medium to work with then just start back with your gh trio and cal mag at whatever week/stage your plant is at.
I don't do soil so I don't know if you have to recharge the calmag like you do in coco.

[dustydundee]

homegrown, I think I will follow that and do a good rinse with some PH water. I'm pretty sure I've been underfeeding it leading to this deficiency.... i guess my only concern/question then is, if this is the result of underfeeding, then by flushing it out now, wouldn't I be starving the plant more of some nutrients because then I'd have to wait several more days for it to dry back out before feeding it again? You'd think I'd be better off flushing it out, testing the runoff, and then feed at the same time after I flush on top of the flush? just askin....

[RetiredGuy]

I have also been struggling with what I believe is a phosphorus deficiency with one of my plants on my current grow. Your symptoms are similar. I had read that phosphorus is best absorbed by the plant above 6.2 pH. I have been feeding at about 6.5 pH, but my runoff is always about 6.2 which I think has contributed to the problem.

The plant with the deficiency is the one getting the most light, so I probably was too cautious and underfed it. I now understand that more light requires more nutes.

[homegrown]

Nope, give it nothing but Ph 6.2 water. Give it lots till it runs out the bottom of the pail. dont test the first batch of run off, give it another good soak till run off and then test. If its not close to 6.2..then you'll need to think about flushing

[dustydundee]

good suggestions. I figure she will be due for a watering within the next day or two. I was thinking I was going maybe a little lite on my veg nutrients, but you think a full flush would be better first? (ok I had watering problems in my last grow, but this one is going much better. my other plants look good. if anything, i'm underwatering this time. I weighing these damn things every night and this guy seems to be light every 2 days or so) In any case, lets say within the next 24-48, she'll be dry. Last time I gave her some bloom supplements because I was thinking phosphate issues. Shall I give her a dose of the normal GH veg trio with calmag, or just do a full flush on her, followed by the GH veg after that dries???

[homegrown]

agree with Jeff, next time you water, PH to 6.2 and run enough water thru it that you can test the Ph of the run-off. Im thinking a full blown flush might be in order.

[JeffInCanada]

The only thing that I can think of to suggest is to test your runoff, try and determine if something weird is going on in the root zone. Sort of looks like calcium def. too but your PH going in is ok for calcium.

[dustydundee]

and what exact mistake am I making? not sure I find this comment very helpful.

[dustydundee]

Hi all, thanks for the replies...

as far as PH, I've been PHg each time to the low 6s. I shoot for 6.25 to 6.5. I ph it every time. I use the same meter for about another dozen plants.

As far as watering every 2 days, I've been weighing each pot and water when its light. When the plant was younger, it was going every 3-4 days, now based on her weight, she gets light every other day. She's in a 7 gallon container and I never let them sit in runoff. I originally had them in 3 gallon pots and transplanted them into 7 gallons a few weeks back cause they were drying out.

[SoOrbudgal]

This watering and pot container is what we practice in the tutorials and all grow sites tell the same thing. If you ignore or try without knowledge mistakes will continue. No transplant, not knowing the size of the plant will get you into issues like this. Lack of proper water needs and over feeding. Hopefully they don't suck up the runoff and sit in water.

[PeterMatanzas]

Side issue: water when needed, not on a schedule like every 2 days.

[PeterMatanzas]

When you’re watering be sure to mix up your pH, i.e. go with 6.5 one time, next time 6.3, then 6.5, then 6.2 ... I don’t mean exactly like that but make sure you aren’t always going with the same pH. Almost every time I have a nutrient issue it’s because of a pH problem - the nutrient is present in the soil but the plant can’t effectively use it because of pH

[Farmbuck]

What is your PH ? As I see it, it looks like a mag deficiencies.

[Rqsnlautoproblems]

Kinda looks like potassium def, i'm a newbie though, hopefully someone with more knowledge will be along soon

[JeffInCanada]

Hi dustydundee
I see that browning is happening at the lower and middle leaves...could be PH fluctuation, see below link. Have you been measuring the PH when you add water and nutrients? Could be the cause of other deficiency signs as well.