Seedling leaf spots
I'm on week 2.5 after starting seeds and I'm starting to get some spotting on two of my plant's lower leaves leaves. So far I haven't noticed it on any of the younger leaves. It started with one plant (image1) and now it's starting to show on the second (image 2). Plants were started in a mix of FFOF and peat moss. I know this soil can be hot for seedlings so curious if it's some early nute burn from that.
Tent temps range from 60-78F with humidity around 65-80%. Humidity used to vary a decent amount but I have to running closer to 75% consistently using a bucket and rag. Light is currently about 18" from seedlings which is could be a bit close but I don't think this is light burn. I keep water off leaves when water and water only when soil is dry. Water pH is probably around 6.8 but I've struggled to keep it consistent with it maybe being at the higher end at times. (I have better test strips on the way).
Any clue what's going on? I tried looking at growweedeasy but having problems narrowing it down. Thanks for the help and let me know if any other info is helpful!
Posted Dec 27, 2021, 2:48 PM UTC
I have limited experience, but Imo your problem has to do with a Mg deficiency due to Ph lock. Ive heard that Ph strips are not the most reliable measurement on the market, but if you assume 6.8 then the potential margin of error is wide enough for your Ph to actually be above 7, after which Mg does not get absorbed. I would try pinpointing the Ph before adding extra Cal-Mg, but maybe just some added Magnesium would help as well since its definitely not nute burn. Best of luck and keep us updated.