HELP! Light spots that don't quite match anything I've found online

[LittleBitz]

Hi everyone, first time grower, long time lurker on GWE. I was excited to get my first grow going with a couple Nirvana Amnesia Haze AutoFem seeds. Sprouted within a day, growing good in solo cups under my shiny new 400w mh light with wing reflector on a 18/6 schedule. Planted in ProMix Ultimate Organic Mix. Temp is sitting around 78-80 in my closet with a RH about 40. (Im out of budget for a humidifier right now) There's a fan in the room, but not blowing directly on the plants. Just under two weeks in I noticed a light spot with defined edges on one leaf of one plant. A few days later it's spread.

I can't find any critters on the plant. Unfamiliar with how small spider mites are supposed to be, I put a leaf under the microscope to check out a few TINY specs, but they turned out to just be bits of soil/dust. At first I thought the lights might have burned the plants where water drops had been, but it has gotten worse since then. (I had been misting the seedlings, but have since stopped)

Also, FWIW, I'm brand new at this. I welcome the constructive criticism and I know things can always be done better, but I'm also aware that cannabis is a durable plant that with some basic needs will grow, flower and yield some amount of delicious bud to hold me over while I learn and improve my setup. Help PLEASE!

Cheers!
LBz

[Toker1]

First...Raise your grow room humidity (40% is way too low). Many strange issues like these are caused by low humidity.
How close is your light to your plant?
the water drops from the spray can cause this type of damage as well. Once the damage occurs, it doesn’t surprise me that it spreads.
Do not directly mist the plants with plain water... you will eventually run into mold if you continue to spray them.
Neem oil is a great companion for your plant. But spraying anything during lights on is risky.

[Chefbjy]

They might need to be transplanted from solo cups. Hard to say without a whole pic but that's my guess.

[Toker1]

It says he noticed the spots at 2weeks.

[Chefbjy]

Yes and root problemscan cause all kinds of symptoms. I know people on here aside from myself have vegd with lower humidity then 40%. If it's 2 weeks in a solo cup it may need to be potted up. Looks like the leaves are hanging over the side of the cup. Good sign it needs a bigger home.

[D.A.A.S.69]

Yeah I'm with Chefbjy, Humidity is not the problem, that plant needs to be transplanted, now,
You can't always go by when the leaves reach the side of the cup. You go by the size of the leaves too, that plant has got large leaves, and is probably already root bound, imo.

[LittleBitz]

DOH! Humidity? Really?! It would figure if it was the one thing I didn't have control over! GWE says 40-60 is the appropriate range of RH for veg. If I'm at 40, is that low enough to cause real problems?

Now that I got that whining out of my system, are there any diy humidity solutions to get me by? If I need to by a humidifier, is there anything specific I should be looking for? Or can I just get a small, basic, tabletop humidifier?

Next, how is it that humidity would lead to this problem? This isn't an argument, I want to understand...

Oh, and the lights are about 16" from the tops of the plants.

[Toker1]

I use solo cups for clones and seedlings all the time. I run thought 150 clones per month for the last 3 years...Never had a problem at 2 weeks. Maybe at 4 weeks, but never at two. I’m not going to say it’s impossible, but I will say I have never had a strain so finicky that 2 weeks in a solo cup caused an issue.

[Chefbjy]

2 weeks for clones may be acceptable but I've had to transplant seedlings earlier then 2 weeks and the cups were full with roots. Seeds want to extend their tap roots and can out grow cups easily. I'm not convinced its humidity.

[Toker1]

Chefbjy I just found this... weasel grew a seed and had it in a small container for a bit over 100 days and yeilded 42 grams.

https://forum.growweedeasy.com/forum/growing-community/50026-how-often-to-remove-fan-leaf-s

[LittleBitz]

Chefbjy - The plants were just reaching over the edge of the cup the other day when I noticed the spots... I would have already transplanted them if I wasn't freaking out about these spots! lol

Toker1 - Rookie mistake, I stopped misting them as soon as I saw the first spot since it was shaped a little bit like a water droplet. What you're saying makes perfect sense.

[LittleBitz]

I've got a lot to learn... I would have guessed that there was a bigger window than a couple days to get them transplanted before the pot size would start showing such stark symptoms on the leaves. I'll get them transplanted tonight.

Is anyone confident in saying this doesn't look like a pest problem? I don't want to ignore that possibility if something is taking hold of my new babies!

[Toker1]

I highly doubt it’s the time in the cups... unless you are filling the cups less than half way with soil.
Put out yellow stickey traps. If they remain clean after a few days, it’s not a pest issue.

[LittleBitz]

I'll track down some sticky traps.

Toker1 - I'm not saying my humidity is ideal, but I assumed there is a range of acceptability and being one point in or out wouldn't be such a drastic problem. I'll check into humidifiers tonight, too.

[Toker1]

Low humidity can kill a plant, even at 40%. I think what you are missing is that every strain will react differently. Some will show problems at 45% RH. It’s strain dependent. Since you have many veriables, try hitting the center of that range. That way you will ensure that most strains will be ok. You may be working with a finicky strain that is just more fussy. In that case high humidity is your friend as long as no mold is present. The leaves need to absorb water too, some strains require more RH others require less. The 40-60 range is not an exact science... but more like a reference point.

[LittleBitz]

Well, I'm going to try to get the humidity straightened out tonight. Is there anything else you would do or watch for? I'll get those sticky traps, too. I'm sure I'm just being a nervous newb here and overthinking it, but I don't want my first attempt to be a total loss before they're even really going!

[Toker1]

They should bounce back with out issue. They are showing you signs and you are doing the right thing by dealing with the issues. The best growers I ever met are really good at dealing with the issues as they come up. So you are on the right path here.
Watch for slowed/stunted growth...watch for more green leaves being effected. Droopy leaves or losing many leaves.
Keep an eye on the development of those spots (is it spreading faster or slower). Most important, look for new growth, because if she is unhappy... new growth will be limited at best.

[Toker1]

How is this problem going now LittleBitz?