It's been a couple of weeks since your post, curious about the steps you've taken and how they've affected your plant?
Looking at the pictures, it doesn't appear to be a N issue - a deficiency of N starts at the bottom of the plant and the leaves at the bottom or yours seem to be healthy. Likewise, it doesn't seem to be an N toxicity since that tends to make the leaves a very deep green.
With the most affected leaves being at the top, it would indicate light stress. LEDs can be tough when it comes to identifying light stress for a couple of reasons (I use 2 Electric Sky 180v3s so I've run into this):
- LEDs can create light stress without the symptoms of heat stress and many articles about light stress combine the symptoms with heat stress so it's easy to overlook that light can cause symptoms like that.
- LEDs create TONS of light. Light is food for your plants (contrary to general understanding where most believe it's the nutrients you add) and when they get too much light, they aren't able to process all of it. With LEDs, light stress can happen very slowly and gradually over the course of several days/weeks.
With the slow progression of light stress that can be caused by LEDs, because we love our plants, we notice something changing....maybe some chlorosis of the leaves...and we search for solutions. Since it's happening slowly and doesn't look like light/heat stress that we've seen examples of in other articles we don't recognize it for what it is and start chasing different nutrients and supplements and that's a logical response, even if it isn't accurate.
It also looks like they may be experiencing some watering issues. The leaves all look like they're drooping at the ends of them. Ironically, this can be a symptom of both under- and over-watering and can only be sorted out on watching how your plant behaves when it's watered. For example, do they perk back up when you water them or do they stay droopy like that? Are they droopy after you water them or only as it gets time to be watering day? You didn't mention how much water you're providing when you water them, but what's the soil like when you water? Is the top inch dry or is it still moist? Three-gallon pots aren't that big so you may want to try watering less but more often depending on what your soil feels like on your watering days. It's easy to over-water but it's very important that your roots have plenty of oxygen which is one of the big benefits of using cloth pots if you're not already.
Check the distance of your light (check out the manufacturer's suggestions on light intensities/distance/growth stage) and adjust as necessary. Make sure your watering regimen is on point and that you're managing your temps/humidity and see how that helps out.
Keep us posted!
