Green Algae forming on top of pots in greenhouse

[pinkie]

I've noticed that there was a slight film of green algae forming on top of my spring onions in my plastic greenhouse, so I moved them outside, but this morning I noticed the same thing on top of some of my other pots.

Does anyone have any tips to prevent this. should I try and scrape it off, or just leave the pots to dry out a bit. I'm not sure if I've been overwatering. The greenhouse has been mostly closed, although I'm going to start leaving it open for a few hours each day now to ventilate it to see if that helps.

[Bigmallly]

Scrape it off, let them dry out a bit & water from the bottom or water less. You could also dress the top of the soil with Vermiculite to absorb any excess water. It's the surface water that is turning green.

[Small pumpkin]

Lots of my pots do that as well. I just scrape it off.
I often wondered what you use vermiculite for

[pinkie]

Great, thanks. I'll try that, I think I was too worried about everything drying out I was too over zealous with the watering can!

[Bigmallly]

I often wondered what you use vermiculite for

Mix it in with your compost to aid water retention.