yellow leaves

What most others said - looks like a nitrogen deficiency. Since you’re on week 3 in nutrient-free soil, you’ll probably want to start giving it a light dose of whatever veg/grow fertilizer you use. If you were growing in pre-amended soil, you can often wait until week 4-5 without any signs of deficiency. While I don’t think it’s the problem here, overwatering can also cause nitrogen lockout. In my first grow this summer I was overwatering and a few of my plants looked like yours (and I was using FF Happy Frog with nutes added). You may already be in the know, but just wanted to save you some trouble if not! If it were me, I wouldn’t remove the leaves yet until they’re completely dead (hopefully it doesn’t come to that). While they don’t look so pretty, the plant still might be using them and pulling them may potentially cause stress on the plant. Anyways, happy growing and good luck!

If you're still in Promix HP, start adding nutes - you're fine with very light feedings but make sure you're supplimenting Calmag on top of your light feedings of base nutes. For promix HP, feed/water at 5.8-6 ph. If you call Promix, they'll tell you water PH doesn't matter, the alkalinity of it does. But I have hard water, and it's fine if I ph it. To my unexperienced eye, it looks like a lockout or a N deficiency. Check your runoff PH. Should be 6-6.8 in Promix. Anywhere outside of that range is your problem. If you haven't fed and you're still in promix, that's your problem. If you've done everything right, then I have no idea! haha. Good luck!

Yellow leaves from bottom up = N

If you haven't begun fertilizing, now is the time. IF you have been fertilizing, i'd up the N a bit, but look into a couple things first: pH? if soil, 6.8, if soilless a bit more acidic at 6.5 is best. If this is too acidic, that could be preventing N uptake. Also, do you adhere to a good wet-dry cycle? ensure entirity of put gets saturated - this requires soem runoff. if soilless, you should fertilizer each time with 20% runoff.. less so with soil, as you don't want to leech the nutes it came with. Which as you see by the yellowing leaves, it is getting used up quickly. So, you can either up the fertilizaton or up-pot it... depends on many factors what is best -- how big will it be? is it an autoflower or photoperiod plant? An autoflower won't need a larger pot, most likley, and dependon on how large you intend to grow it, if not, will determine if wise to up pot... each time yo re-port you give new soil with new nutrients for roots. so, if in soil and ramping up to full strength, get a little more runoff than previously. Again, a wet-dry cycle is essential. Allow top 1" to dry before next irrigation, feel weight of pot so you can simply give it a tug to determine irrigation date. Always saturate entirity of pot... dry pockets are bad for a multitude of reasons. stick to that habit and the rootzone will be happy, pest free and consistent environment for roots. It seems irrelevant and simple, but if you do this, the plant will remain healthy deep into bloom if fed a balanced diet.

Hello Classified_01, Your plant doesn't get enough Nitrogen. This could be caused by not giving the plant enough nutrients, or then your pH value is incorrect. I wouldn't remove those leaves because your plant is still so young that you don't want to stress it at this point. Good luck with your project, I wish you the best! 👽

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