You can pluck the babies at any size, I have found from experience, that if you wait until they are the size of a nickel they do better, the tiny ones will survive, but tend to take longer to grow to larger size, and some don't even survive. I use a pair of leather gloves, or kitchen tongs when used gently works good to pluck and
plant with. The baby needs to just be firmly pushed down into the soil, so that it is touching the soil, but not buried, water lightly and then forget about it. I like the look of all the babies on the mother
plant and sometime they just fall off and root beside the mother
plant, as you can see from the photo's I posted in the first topic about this:
Echinpopsis Multiplex As far as soil goes, I use
cactus soil, or sometimes I use potting soil with sand added, or mix
cactus soil and potting soil together. I have used strait potting soil and it works alright as long as you have good drainage. My
cactus seems to do fine with neglect, getting water only once every other month or sometimes longer then that. Someone once ask me..."How often does it rain in the desert?" Well that is how often you should water
cactus...Not very often. Hope this helps.