Algae on top seed pods?

Hey everyone!

I just germinated 8 Critical x Jack Herer seeds a few days ago. They seem to be doing pretty well! But I just noticed that I let the seed pods stay too wet on top and have started to develop green/brown algae/mold on top of the pods! A few of the leaves are a little wonky too, but overall look fairly okay to me! I thought it was sparkly because it was wet, turns out it’s algae. Roots and leaves seem to be growing very well!

Any idea how I get rid of this without harming the seedlings? Thanks in advance!


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@garrigan62 we need help😭

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I’ve got this on my rockwool with clones so I’m going to follow in hopes of learning something new. :sunglasses:

10% hydrogen peroxide from the drug store in the water in your your mister. H2O2 kills algae and doesn’t kill plants. I believe there are some things on YouTube about it too. I use Rapid Rooters and I’ve seen algae when I’m outside. Not indoors. My watering jugs are colored green to keep algae from growing. Outdoors all I have is a rain barrel. I see will is replying. Your in good hands.



It’s from overwatering

Over watering

Over watering is one of the biggest mistakes new growers make, reason for this is, because they feel
the need to give there plant everything and will overdue a lot of things and one of them is over
watering. By over watering your plant you soak the roots so much, they can’t get enough oxygen
and slowly die. The plant shows signs of over watering by: Wilting, droopy look, yellow and or dead
leaves falling off, which includes leaves that don’t look dead falling off. One of the best ways to
tell how NOT to over water is by, picking up the pot when it is dry and then picking up the pot after
you water. (This is a reason why it’s smart to use light pots.) When you water, you want to water just
enough to where you see a bit of water coming out of the bottom, not gushing or pouring out
. Just enough to see a little bit, then you know the plant has enough water. To prevent over watering
you can either: add more perlite to your soil, add hydrogen peroxide to your water for extra oxygen,
all the while killing bacteria if any in the soil. After watering, wait a few days to water. Mj plants
like a good watering and then a couple days to dry out in between watering. So it’s very easy t
o over water. Besides the weight of the pot, another way to test if your plant needs water is to stick
your index finger a couple inches into the soil. If the soil at the tip of your finger feels almost dry,
then it’s time to water again. The top of the soil should be allowed to dry out between waterings if it’s
still moist the plant does NOT need watered. You can also use a moisture meter which will tell you the level
of moisture down in the soil. You can buy them at most garden supplies or hydro shops.
Here is a picture of what over watering looks like:

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@garrigan62, thank you for your response! With that in mind, do you have a recommended remedy? I assume simply watering less will solve them from being overwatered, but is there anything I can do about the algae now? Maybe the peroxide technique @OldSkunk recommended? And when you say mister, you mean in the bottle I use to water them currently, correct?

Thanks again guys!


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Most of us use a mister for seedlings. Without one you’ll overwater and can drown the seedlings.

All you want to do is spray the seedlings leaves and a small amount at the base 2x a day if you can. The hydrogen peroxide will kill the algae without harming plant. I use it to start seedlings. Look up the thread THE PERFECT GERMINATION METHOD IF YOU FOLLOW DIRECTIONS. I have 100% germination on my plants. If your uneasy about it. Just do a Google search on h2o2 being used to kill algae. You really need to buy a mister for your plants asap

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Thanks for that! I actually already have one, so I’ll just load that up and start the curing process. Thank you so much for your advice!


Do the peroxide.

The algae is changing the balances and algae is choking the roots. as well as the overwatering.

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I used to let the surface dry , then scrap off the surface and then sprinkle some cinnamon powder on top.

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Is ground cinnamon the same as cinnamon powder? I get most of my spices in the bulk section and they had the powder, instead of ground. I couldn’t tell if it was just named differently or a completely different product

Alright everyone, thanks so much for all of your help! I’ve just sprayed the guys with 10% h2o2 solution PHd to 6.5. It’s all in the hands of St. Mary now. Fingers crossed she’s not feeling malevolent today.

They are different , also Im not sure when it comes to product naming in the US.

Cinnamomum verum, or C. zeylandicum or Ceylon cinnamon, is considered real cinnamon, but Cinnamomum cassia, or Chinese cinnamon, is more commonly sold in the United States as cinnamon

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I’ve been using the peroxide for a few days now. Haven’t seen improvement on the babies yet. A few may actually be getting a tad worse. Leaves looking like they’re shriveling. Lots of ridges on the sides. They’re to be transplanted into the main system tonight, so hopefully that helps and doesn’t just seed the hydro water with algae. The water in the main system is chilled, so hopefully that’ll help. Pics tonight. Please cross your fingers for me. :slight_smile:

Fingers crossed buddy🤞

No peroxide every day. You are only trying to kill the algae. Too much peroxide. Just regular water. If you’re growing in soil, despite what some will say, IT WON’T HURT THE PLANT to have algae on it. If some other growing media, I have no idea what to tell you


Thanks everyone so far! The guys still don’t look amazing, but I think I’m at the point now where it should be able to recover. Enough of a root system has been established that I can put them in the main system now, and just let the rooter pods dry out and the algae die. The main basin is chilled and sealed with hydroguard, so hopefully the algae won’t be able to survive in the basin and will simply die off. I’ll keep updated.