Im kinda iffy when it comes to feeding my plant's i always think I'm gonna kill them! I usually do it every 4-5 watering i dilute it in a spray bottle with purified water, sink water is to harsh for plant's let alone human beings! Its a MG cacti+succulent plant food, (Which is why I'm kinda resistant to using it) i spray a little on then i water with regular water the next few times the soil is dry. I JUST lost a bid off of one of my flowering cacti cause someone thought it was a fluffy bug (SMH
So kinda upset about that! But my rebutia decided that it was gonna make up for its fellow cacti losing a bud by opening another flower for ME and showing me a promise for another one to open at any time, it still has 11 more buds to open on it!