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Week 5 yellowing, N def or just fading?
Running a Zkittlez photo right now, week 5 of flower, and i'm seeing yellow creeping up from the lower fan leaves. Nothing dramatic yet, maybe 20% of the lowers. My pH is dialed, EC around 2.1, and i'm running a pretty standard late-veg formula that I haven't bumped up for flower yet. Wondering if i'm being paranoid.
At week 5, how do you guys tell the difference between normal senescence and an actual nitrogen deficiency that needs correcting? The timing makes me second-guess myself every run. Natural fade usually starts lower and slow, right? But so does a real N def.
My current N-P-K ratio is sitting around 1-2-3, which is where I usually land mid-flower. Part of me wants to push the N slightly, maybe go 1.5-2-3, but I also don't want to feed nitrogen into late flower and mess with the finish. Curious what signals other growers look for before they decide to act or just let it ride.
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Week 5 with 20% lower leaf yellowing and that NPK ratio, i'd actually lean toward letting it ride before you do anything. Here's what i watch for to tell the difference: real N def usually moves faster and hits mid-canopy leaves within a week or two, and the leaves tend to go uniformly pale before they yellow. Senescence creeps slower and the color is more mottled, kind of a warm yellow-green before it drops.
The thing nobody's saying yet is that your EC at 2.1 isn't low, and your pH is dialed, so the plant is eating. If it were genuinely starved you'd probably see it moving quicker and the affected leaves would look more washed out than yellow.
I'd give it 5 to 7 more days before touching the N. Where Zkittlez starts to shine flavor-wise is exactly when you stop fighting the fade and let the plant do its thing. Pushing nitrogen now to save some fan leaves you're gonna strip anyway risks greening her back up and dragging out the finish, which can mute those fruity top notes that make the strain worth growing in the first place. That would be the real loss here.
The point about N def moving faster is solid in my experience, but I'd push back slightly on waiting a full 5 to 7 days if you're at week 5 of a Zkittlez run. Depending on your pheno and your environment, you might only have 3 to 4 weeks left, and if it does turn out to be an actual deficiency, that's a tight window to course correct without stressing the plant. I'd keep a closer eye on the mid-canopy leaves every couple days rather than setting a timer.
week 5 with 20% lower yellowing and the feed hasnt been bumped for flower yet, id lean toward actual deficiency before i even worried about the timeline. the senescence argument would carry more weight if the formula was already dialed for flower. watch the mids but also just bump the N a little now and see if it holds, waiting to observe isnt free when youre already behind on the feed.
The pace thing is what i always watch first too, but i'd actually flag the formula before anything else. You said you're still running a late-veg mix and haven't bumped it for flower yet. That 1-2-3 ratio at week 5 flower is a bit lean on P and K for where the plant should be right now, not dramatically, but enough that the plant might be pulling harder on stored N to compensate for general nutrient stress. It can look like an N def when the real issue is the overall program lagging behind the plant's stage.
i run autos so my timing is compressed and i can't always compare apples to apples, but the signal i rely on is whether new growth looks healthy. If your tops are still green and vigorous and only the lowers are going, that's almost always the plant doing its thing. The moment i see mid-canopy or newer growth starting to pale, that's when i actually move.
Might be worth bumping the flower formula before touching N specifically.
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