Is this nutrient burn or another issue?

I’ve just started feeding my plants with a mix that is approx 12/3/6 npk, its ‘Thrive.’ been feeding once a fortnight with this stuff, following the instructions on the bottle. anyway after feeding them two days ago the top leaves have been bleached for some reason. It doesnt look like nutrient burn to me, judging from the other photos i’ve found but i’m only a first time grower.

The only other possibility is its the bug spray i’ve used on them, sprayed it around the same frequency, its an organic mix of chili, garlic and pemethrin. surley this wouldnt cause this discolouration? The photo looks like its glare from the light but its actually lighter colouring in the leaves… Thanks for any help!!

What are the temps where you are growing? I ask cause it looks like heat stress,also what’s the ph at the root zone

It could be nute burn. It does look a little like a nutrient salt toxicity. The pH at the roots, or pH in general or in the water you use, might also be a consideration, as well as heat, and maybe the spray, maybe.

Check out this from Robert’s blog for a way to test your soil and confirm or rule out the pH or EC/PPM/nutrient concentration as being the problem or not:

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Thanks guys, ph of the soil is 7, measured it today, growing temps are around 15 degrees celcius, a little cool I know…

Yeah, I’m mostly worried about your nutrient concentration in the soil, I’m really thinking nutrient salt toxicity, also known as nute burn. Nute burn can look differently depending on which nutrients are the main cause of the burn.

MacG is right on! You should not start seeds in such a “HOT” soil mix. The mix you have would be fine to re-pot a mature plant, into. :slight_smile: