Help! I have more seedling mold!

So as some of you may have read in my other posts, i recently sprayed my seedlings with citric acid fungicide because one was overtaken with fluffy white mold (i threw away the one that was covered). I have since transplanted my seedlings and gotton rid of the icky peat cups they were planted in. Now one of my seedlings has a lil fluffy white mold on it.

I dont understand why… i treated it exact same as others, damp but not soaked soil, only spraying the dome to water it. Lifting up the dome a couple times a day to give it air. Humidity in my tent never goes above 50% (outside the lil domes that is)
Someone mentioned hydrogen peroxide for mold. Can someone tell me how to safely apply it? I currently have removed this seedling from my grow tent and put it outside. Do you think this seedling can be saved? Should i treat my other seedlings with the hydrogen peroxide to make sure they havent been infested as well?

Your soil is far too wet and that may be contributing to the problem. Cannabis needs wet/dry cycles for proper root health. A plant that size should only be given a few ml of water per day. Water and then let the soil dry out before watering again. Roots need oxygen and all a seedling has is a single tap root. It makes it very difficult for the roots to access oxygen if the soil it wet all the time.

Are you still using a dome? I would discourage the use of a dome if the soil is wet. Soil shouldn’t be watered at all if using a dome.

Keep in mind that overwatering is by far the most common cause of seedling loss. It is extremely important.

I didn’t notice the wet soil problem when we traded posts the other day. Now it makes sense.

All you can do at this point is let the soil dry out, spray with peroxide to mitigate mold, and hope for the best.


I actually havent watered the soil at all since i transplanted them. I must have wet the soil too much when i was filling these cups, it didnt feel soaked but it must have been too wet. All i have done since is mist the inside of the dome. I will take the domes off for now until they dry out a bit.
I assume i dilute the peroxide with water, do you know what ratio? And do i want to spray the dirt down as well or just the plant itself?
Lastly, would you try to save the one that already has mold or just toss it?

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Your soil should be completely dry if using a dome. Maybe it’s the lighting, but that soil looks soaked.


I do think the lighting/ the camera makes it looks worse than it is but yeah i definitely over wetted mine then if it should be dry. Its not what i would consider soaked but it is wet

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Absolutely no. Let that soil dry out. I can’t overemphasize how important this is. The excess water is what is driving your mold problem and few seedlings will survive overly wet soil.


You can wait it out, but that seedling isn’t going to be capable of absorbing all of the water in the soil. I’m skeptical it would make it.


I would avoid adding anything with any moisture to the plant or the soil. As suggested, it is far too wet. The soil is damp enough, and the seedling close enough to it, that leaving it under quality lighting at proper height/intensity, should be fine.

Looking back through your topics/posts, it looks like overwatering. The bags and the cups are all pretty soaked. For the first couple of weeks, there’s really even a need to get out the watering can.

After planting, ½ cup of water on and close to the seedling is enough for the first few days, while using a humidity dome. The plants are taking in most of the moisture from the leaves at this time, while the roots are growing.


Just discovered i forgot to poke drain holes in the cup holding the seedling that molded. :woman_facepalming: They all need to dry out some and they shouldnt be wet enough to need to drain but im guessing its no coincidence that the one i didnt give drain holes is the one that molded.

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Dont know if she will make it but right now shes living life mold free outside. Shell be allowed back inside later.

I would put a cup that isn’t clear under that clear cup. Clear cups promote algae growth.


I have gotten the girls mostly dried out but now the bigger 2 look like this.

Most the ones in the cups still are looking better than these.
They are currently in ocean forest soil, which i have since learned can burn seedlings. Do you think that is whats happening here?
I have some happy frog on the way that will be here tomorrow. I got it for the other seedlings but now im thinking maybe i should repot theses ones as well? Would you move them to the happy frog? If so, how urgently would you want to replant? I can wait for the soil to arrive tomorrow or theres a hardware store only about 8 miles away i could get it from today.

I think my next round is going hydroponic instead. It looks easier.

I’m a soil guy and in soil you have time to identify and correct a problem. Hydroponics grows fast but also goes bad twice as fast if anything goes wrong. I’ve learned in my life when something looks easy that means somebody great is doing it.


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