photo? is it actually moss or green algae?

It's moss for sure. I'd post a picture but I hate how critical this forum is about soil/pots/watering/light/etc my plants are perfectly healthy and I want this thread to be about the moss only.

At first it was nice to get advice about soil but then literally every thread became about soil and I'm extremely bored of that topic. My soil works for me.

I don't believe the moss itself harms your plants, (please, experts, correct me if I'm wrong! ) but that if moss is able to grow in your medium, it's a good sign that conditions are not ideal for c & s. Moss needs fairly consistent most medium to survive, and we know that we want our medium to be drying out completely between waterings, with some exceptions.

I'm sure it makes a huge difference depending on species. .. what seedlings are you growing? Cactus? Succulents? What species?

I bet the request for a pic was more aimed at ID of moss vs other things it might be (lichens, fungus, etc) and to be able to trouble-shoot. A picture is worth a thousand words.

-Amy

I'm growing a bunch of different cacti. But to grow seedlings they need that humidity and moisture according to everything I've read + experience.

If the moss doesn't cover the seedlings too much then a little moss should be OK. Don't let it become too tall. You can trim the moss so it doesn't over shadow the seedlings. If it is young moss you might be able to use tweezers and pluck it out without disturbing the soil mix a lot. However, you want to grow cacti/succulents and not moss so should eventually transition to conditions that are less favorable to the moss. In nature the humid moist conditions don't last a long time

I'm having enough trouble even growing JUST moss! :/

got a pot of hydrophobic peaty sifted fines, takes a while to rewet each time but it still doesn't stay moist long enough to sustain the moss patches I rescued from other pots & tossed on top

Hi Kiki, I think this forum is critical over soil, pots, watering, light, is precisely because that's all plants need to grow and thrive. The challenge in growing C&S is because there are so many varied species from all over the world in different growing habitat and different requirements in growing them.

It's great that your plants are fine and your soil works best for you. That's all that matters, but in my humble opinion in growing. There still isn't 1 best soil that works for me yet, this why I'm still so critical in tweaking and experimenting soil/water for every single species until I find the sweet spot.

This forum is a great platform to learn, like Rina mentioned. Information or instructions might sound repetitive sometimes, but they largely benefit many people reading these posts.

To answer your question, there is no way we can identify these "moss" unless we have a picture to ID it.

You are right to say C&S seedlings need moist soil to grow healthily, this is why my first batch of seedlings had algae growing because I didn't sand the top soil, and they really deter young seedlings from growing.

I've also tried growing moss on my recently bought bonsai, and I must say I'm quite bad at watering my plants, perhaps that's why they (the moss) all died and dried up.

And FYI, moss needs to be planted, they have roots too, they don't float around like spores in the air like algae, which grows almost anyway.

Yes! As bernardyjh said, we are critical especially about soil simply because it an important thing to be critical about! Well, you may think it boring, but I actually find it quite interesting, and it is always fun (for me) to learn new things!

That aside, moss won't do any direct damage to your cacti, but it can start to grow out the cacti if it isn't kept down. And, I also have to say, if you just used something like pumice, Turface, or perlite, you wouldn't have these problems.

I stumbled on this blog on C&S seed culture. It might be beneficial for you to read through it, and also gives you a good spin away from us - critical soil maniacs. lol

http://living-rocks.blogspot.com/2014_10_01_archive.html

Does your moss look like this?

http://4.bp.blogspot.com/-SuFEY49bpvc/VFE931z2MnI/AAAAAAAAAHk/KxBxNqngVE0/s1600/IMG_4712_500KB.jpg 

If it does, it's probably too moist and algae is taking over your plants.

NOTE: Algae will KILL and outgrow your seedlings!

And to add on to palm's comment, usually seasoned growers will add a light layer of horitculture sand/turface to prevent the growth of algae because the dry up fast on the surface so they don't stay moist enough for algae to grow.

Best of luck.

I'm using horticultural sand as the top layer with my seeds and it's been working very well. Helps prevent tiny seeds from falling through and doesn't grow algae like pure perlite.

Turface fines are working well for me too, but I've been adding that in the gaps for seeds that already have sprouted. Algae hasn't grown on it either. Takes a little longer to absorb water and has a higher tendency to float.