My little saguaro babies that I have nourished from seed during the last eighteen months are getting quite fat and green. I've been growing four of them in a three-inch-diameter pot until now. The two biggest of them are about an inch tall and an inch wide. I'm afraid of damaging them, but I don't want to leave them to their Darwinian fate. At the same time, I worry that separating them will damage their roots and perhaps kill them. Repotting when they're smaller should mean their roots will be less tangled (I hope!) and therefore less prone to damamge. Waiting till they're larger should mean they'll be stronger and better able to withstand the shock. When will be a good time to separate them into pots of their own? When they're smaller? or when they're larger?
how old are the seedlings? could you post a pic of the pot? with something on/next to it to indicate size/proportions.