What am I looking at? pH? P&K def?

[thelastrebel]

Hi guys, any advice appreciated.

I've had signs of nute burn for a long time on this girl and after feeding last night I noticed almost immediately the leaf tips were getting worse, so I decided to flush out some of the feed with plain water about an hour after feeding. Not sure if that was a good or a bad move but it's done anyway. Today, as well as the burnt tips I've got a bunch of dark patches that look kind of like necrosis and kind of like the plant's been sprayed with something, although I'm fully confident it's not got splashed that high up during feeding.

The pH seems to be too high for some reason and the symptoms look a bit like pH flux? They also, if you take into account the reddened stems and petioles and tips, look like a combination of P&K deficiency to my eye?

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Soil or hydro or coco: Soil

Strain: RQS Quick One, a bit stunty from previous issues

Photo or Auto: Auto

plant age: 8 weeks

pot size: 7l

has it been repotted? and when?: never

soil type: plagron lightmix/batmix

nutes or additives used and how often for soil: Plagron alga bloom, 1/4 strength and green sensation 1/2 strength. I've been feeding every watering since it's only taking water every 3/4 days

Air temps (max min): recently 22C-27C

Res temps (max min): n/a

humidity: Higher than I would like, varying between 50-60%

lighting type and wattage (hps, led, cfl): LED LM301B strips, only 20W but dimmed in response to light stress

Light schedule: 20/4

ph level: This might be a problem, the runoff water last night measured at 7.0

[Ben.g]

pH 7 isn't that high in flower and shouldn't be locking out p n k.

Is it under fed? I dunno

[MonsterEnergy]

soil p.h buffers to 7 that's totally normal


how much is it drinking in 4 days?
is the pot actually dry before you water?

[thelastrebel]

pH 7 isn't that high in flower and shouldn't be locking out p n k.

Is it under fed? I dunno

Thanks for dropping in mate. It's possible it's under feeding and I'm misinterpreting the singed tips as nute burn when it's actually a K deficiency. Odd that it would spike after a feed if so but I guess it's always possible that I'm seeing things. She's a lot worse than yesterday so clearly the straight water hasn't helped. I think I'll have to up the feed and see how she responds to that?

soil p.h buffers to 7 that's totally normal


how much is it drinking in 4 days?
is the pot actually dry before you water?

Thanks man. Weird, I think of soil as being pH 6.3-6.5, maybe I need to go back to the books! She's drinking roughly 1l each time, I'm waiting until the top almost an inch of the soil is bone dry, though it does seem to drain very slowly this soil so it's possible that's still too often. Shopping list for next grow definitely includes a bag of perlite!

[Kurdt]

Im sure i read somewhere before on here but ive noticed with my last 3 grows under LED as well that Ive had cal-mag issues, usually in late veg.(might just be coincidence?) They can go pretty pale like their not getting enough nitrogen,so naturally i added pm grow which led to burnt tips but after a few doses of cal-mag it seemed to sort itself out and had no further problems.

[MonsterEnergy]

they need cal/mg more in flower than veg though ''soil growers'' that doesn't include anyone who has soft water or hydro
the leaf tip burn is very minimal, you took them to peek feeding - that's a good thing

cal/mg shows threw lower leaves turning yellow between the veins

[thelastrebel]

Im sure i read somewhere before on here but ive noticed with my last 3 grows under LED as well that Ive had cal-mag issues, usually in late veg.(might just be coincidence?) They can go pretty pale like their not getting enough nitrogen,so naturally i added pm grow which led to burnt tips but after a few doses of cal-mag it seemed to sort itself out and had no further problems.

Probably something else I need to think more about next time, I've been using epsom this grow but might get a full cal/mag for next time.

I'm sort of inclined to give her a booster feed tonight, maybe a bottom feed with bloom nutes, any thoughts?

[Ben.g]

Give the feeding a shot Rebel. If plain water hasn't helped.

Just when I saw the half strength nutes made me think, I'm sure (although don't quote me) that plagron light mix only has enough feed for around 2 weeks.

Hope it works out for you, keep us updated

[MonsterEnergy]

Thanks man. Weird, I think of soil as being pH 6.3-6.5, maybe I need to go back to the books! She's drinking roughly 1l each time, I'm waiting until the top almost an inch of the soil is bone dry, though it does seem to drain very slowly this soil so it's possible that's still too often. Shopping list for next grow definitely includes a bag of perlite!

should have said any good soil will buffer to 7 ph

[thelastrebel]

Give the feeding a shot Rebel. If plain water hasn't helped.

Just when I saw the half strength nutes made me think, I'm sure (although don't quote me) that plagron light mix only has enough feed for around 2 weeks.

Hope it works out for you, keep us updated

Thanks fella, I'll give it a go, bottom feeding so as not to suffocate the top of the soil too much hopefully. I'd been keeping nutes light due to the constant singed tips I've had but the more K def pics I look at, the more I think I've transitioned from nute burn to K def without spotting the difference.

Half the soil is lightmix half is batmix, which by all accounts is hot enough to reboot the sun, but even then it can't last forever!