Hi, i got a small cactus from a friend (i believe it's san pedro or something) and keeps falling over when i don't water it for a few days. I believe the two are too near together and i think i should rip one of them out. What is the best way to do this? Is it possible to preserve the second one? Thanks fabian
They are too small to identify, but I don't think it is the proximity that causes the problem. They look like small (how big are they?) seedlings, and seedlings dry out faster than adult cacti and start to bend. Seedlings are often grown very close to each other without negative effects (except that they might grow slower if the pot is very crowded). They can be separated if you want to, but it is always a risk since the roots will get damaged. Damaged roots are susceptible to basal rot, especially in a peat-based growing medium like yours. Unpot them, separate the roots using you fingers, let them rest in a cool, dark place for a few days and repot them. It is probably best not to water for a few more days after potting (but keep them out of strong light/heat).
If they were my plants I would separate them and put them in individual, smaller pots. Too much soil is something else that can cause rot.
No, the roots should be dry. If the humidity is high fungal and bacterial disorders are much more likely to attack the wounded roots. Adult cacti can lie like that for several weeks, but these are less robust seedlings. When I repot seedlings I typically do that directly after unpotting, and I water them immediately, but with a solution of 8-hydroxyquinoline, which acts as a fungicide/bactericide. Without such things I think it is better to move carefully.