Lower leaves turning brown

[MrKush42069]

Latest autoflower grow. Lower leaves started to fade to a pale green, then yellow, then brown between veins and were splotchy. On new growth I'm noticing yellowing tips. I think this may be a pH issue as my soil pH was measuring ~6.5-7.0 with soil strips and about 7.0 with a probe. I've removed the affected lower leaves and started watering with a more acidic water. Just testing if my intuition and approach seem correct. I also made sure they had enough N with an organic fish fertilizer.

I also raised my lights about a week before this picture and added a second oscilating fan because I thought it could be either light burn or leaf septoria, but now I'm thinking pH lockout. Two other plants in this grow are not showing the same signs of stress although another one did have some mild leaf fading. This one was the worst.

Edit: sorry... here's the full link. It seems to work on my end: https://imgur.com/a/gm9oARz

Edit: additional information: seed was planted Feb 1 in amended soil (gaia green 4-4-4 and 2-8-4 bloom, worm castings, perlite). I think my problem started with me mistakenly pulling water from the untreated storage (pH somewhere between 7.0 and 7.2).

[Gingerbeard]

The only things I see on your imgur link are cats and ads. Can you post here?

[GrowNinja]

I got trains and anime... weird

[Bluey]

The link is a general one so not working.

Re the problem if you dont have oests or bugs you are probably taking the correct approach bit try and keep pH in the 6.5 to 6.8 range for flowering in soil. Do you have a PK suppliment you can add at half strength for flowering? What week growth are you at?

[MrKush42069]

The link is a general one so not working.

Re the problem if you dont have oests or bugs you are probably taking the correct approach bit try and keep pH in the 6.5 to 6.8 range for flowering in soil. Do you have a PK suppliment you can add at half strength for flowering? What week growth are you at?

Sorry about the link. I did edit it. Not sure what happened the first time. It shows the full url in the link section but it strips the unique code when the post is viewed. How embarrassing for a first post.

I amended my soil with gaia green 4-4-4 and 2-8-4 bloom, worm castings, and a bit of perlite - found this soil holds water a bit much. Currently in week 6 since seed (planted seed Feb 1, 2025) I'll top dress with some worm castings and the current plan is to include either more of the 2-8-4 or I may switch to Fox Farms Tiger Bloom and Grow Big. I recently gave them their last "veg" feeding (organic fish 5-1-1 fertilizer in water) a little more than a week ago, so the plan is to switch to the PK feedings next week.

I foolishly was watering them for about a week with unmodified well water. Usually my water has been 7.0 but a recent test showed it is now more alkaline at 7.2. I've since corrected the pH but I've already done the damage.

[Gingerbeard]

I think your last sentence nails it. Your picture shows old damage, nothing new or ongoing. 7 is in the high range for soil. If you lowered the pH, you should be back on track.