I bought a barrel cactus a couple of years ago and it used to stand up fine, but now it's gotten soft and flops over to all sides. I have it in a ceramic pot with regular soil. What's wrong with it and how do I fix it?
Don't water it more thinking that'll help it, because the problem is probably root rot from too much water. Barrel cacti need very little water and soil that drains fast, so first thing is to take it out of the pot, check if the roots are black and mushy, and if they are, cut them off with something clean. Then repot it in cactus soil (or regular soil mixed with plenty of coarse sand) in a pot with drainage holes, and wait a couple of weeks before watering it again. If the roots look fine, it might just need better substrate because regular soil holds too much moisture.
The globe cactus gets soft when the roots rot, and that almost always happens because of too much water or soil that doesn't drain well. The regular soil you're probably using holds too much moisture - these cacti need sandy substrate or one with perlite so water passes through quickly. Before watering it again, take it out of the pot and check the roots: if they're black or slimy, you need to cut off the rotten parts, let it dry for a couple of days, and replant it in fresh soil with good drainage. Oh, and something a lot of people forget: even with perfect soil, in winter the cactus barely needs any water - some go months without watering if it's cool.
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