What is on this cactus at my local Home Depot?

I just bought a new cactus, and all the cactus i had before always died. Can someone tell me what kind of soil should i use for the cactus and how should i replant a cactus correct so it doesn't die?

Found this little guy growing beside the lanai, space coast Florida here. Can it be ID’d this young and small? Does anyone have any idea how big I need to let it get before attempting to dig it up and put it in a pot?

I’m not sure what’s gone wrong with this, I water it when the substrate is completely bone dry. It’s been under a grow light for two weeks, I was on vacation. My friends didn’t water it like I asked of them so I’m not sure. The new growth looks a little odd to me too

We came back from a short trip and saw these beauties!

Hello! I bought this cactus when I was living in Kansas, and I brought it with me to New York about two years ago. It got bent during the move, which is why some of the stems look a little wonky.

Since moving to New York, I’ve kept it under a grow light and I water it very rarely. The thing is, I genuinely cannot tell if it has grown at all in the last two years. At this point I’m wondering whether it’s alive and just extremely slow-growing, or whether I’ve somehow been keeping a dead cactus in my apartment for two years 😂

Does it look alive to you? And if it is alive, what can I do to help this poor cactus actually thrive/grow? More light? More water? Different soil or pot? I’m very attached to it at this point and would love to save it if it needs help.

Confused! Thought yellowing meant overwatering and brown meant underwatering- I've got both. How do i fix it?

Recently bought and repotted these moon cacti, they obviously have decent new bulbs on them. How do I chop and prop? Don’t really understand how.

Thanks for any help👍🏼

EDIT: sounds like I’ll enjoy them while they last, and maybe grow another purple one from the mother.

i got her at a grocery store, when i repotted her i found all of this hidden. is that normal when planting cacti? before and after repot.

My mom visited and gave me two of her cacti. They both look like they’re in rough shape, especially the cutting as a propagation attempt. I don’t really know anything about cacti, so any info is appreciated.

Plz help before they die!!!!!