I made a terrible (i hope not that terrible) mistake when growing Pilosocereus pachycladus cacti from seed, i sowed them back in November. I know it's probably not the best idea to sow them right before winter. However i put them in foil and gave them a lot of light. They germinated beautifully in few weeks as i expected and then i did put the foil away. Then they stopped to grow at all. its like 6 months since they germinated but they still look almost the same, now its summer but they are too small to put them on direct sunlight and i don't know if they wont start to rot if i put them back to foil, Only hot enough place with enough light is outside on direct sunlight, but that's exactly what I'm afraid would kill them.
I never grew cacti from seed so i really don't know what to do now, any suggestions ?
Thank you for any answers!