Soil composition and watering for san pedro cuttings?

[crouchtig]

I've ordered some 50-60cm san pedros with the intention of planting the tips as cuttings. After looking online there's a lot of general advice but I feel I'd like something more specific.

After waiting for the cut to "scab over" my plan is to put each cutting in a medium-sized flower pot with a mix of maybe 50% soil (would store-bought compost for growing veggies in be ok?) and 50% perlite. Is this the right kind of ratio? Do I need course sand as well or is that optional? Would it be a good idea to put gravel in the bottom to improve drainage?

Also what's the best way to judge when and how much they need watering? I've heard that once a month in summer and not at all in winter is best, but I still don't know how much water to give them each time. I assume the amount of water varies by cactus, pot size, and temperature, so presumably deciding how much water to give is based on soil dampness? Would I put water in the top of the pot or in a saucer underneath?

Sorry for asking so many questions, but these things aren't cheap and I want to give them the best chance of survival. Thanks.

 

[icefui]

i can tell you that when you cut the top of a san pedro, you can either put it on top of a newspaper to absorb all the water from the cutting and keep changing so it doesn't rot or wait for the water to evaporate open air (if it's summer), after it gets like callus it will start to root (if you put a fresh cutting on top of dried soil it could work but it could also rot the bottom). when the root gets like 2-3cm or 1inch something like that you can put on store-bought soil and water it a little bit with a sprinkler, 2-3hits once a week.
i had success both ways but the newspaper works best. that cutting was just a segment cut on both ends with 15cm high, but something like 8-10cm would be perfect, and i would say that a san pedro with 50cm could be cut in 6 pieces that would root and get "babies" that within a year had grown up and you start again, by taking them from the "mothers", let the bottom dry up and replant them.
then you eat the mothers and keep 6 nice cacti

yet, i don't know if store-bought soil is the best choice and the watering maybe maybe isn't like that but it works.

anyone can help?