Any idea why this one might be shriveling, and anything I might be able to do to fix it? It didn't have much direct light for a while, but I've got it in a sill now.

When did you last water it?

mcvansoest said:When did you last water it?

About a week ago. It's on an every 2 week watering schedule.

I see have seen them do this some time, sometimes it is just something the plant goes through because of one reason or other and it is just fine, but it can also be a sign of the start of some issues - either too much or too little water, which unfortunately can lead to the same looking symptoms. If it is inside on a two week schedule that could be a bit rich but that does depend on temperature, humidity and how quickly the soil dries out.

Do you ever check if the soil is dry at depth right before you water?

mcvansoest said:I see have seen them do this some time, sometimes it is just something the plant goes through because of one reason or other and it is just fine, but it can also be a sign of the start of some issues - either too much or too little water, which unfortunately can lead to the same looking symptoms. If it is inside on a two week schedule that could be a bit rich but that does depend on temperature, humidity and how quickly the soil dries out.

Do you ever check if the soil is dry at depth right before you water?

I actually just started checking for dryness with a meter. My tendency has probably been to over-water historically, but honestly I mostly just stick to 2 weeks. My house stays around 75 degrees, and is very dry (desert southwest).

Yeah and that is the tricky part, while the temperature inside might be fairly low for the cactus, which would make it seem that watering a cactus every two weeks while inside is too much, the dry air and probably regular air conditioning tends to suck moisture away from plants (we have more trouble keeping our indoor house plants happy and watered than I have keeping my outside in the blazing heat of summer cacti happy), but with cacti it is all about making sure the pot is just about fully dry at depth before you water again especially since 75 is on the low side for cacti to truly thrive.

If you notice that the plant is bone dry at depth with your regular schedule just check when that occurs and adjust your watering schedule accordingly and if it was too little water the plant should perk up, the same with overwatering but then there is a chance that the shriveling is the portent of some kind of rot either in the roots or in the cactus body. So at that point you may want to see what condition the roots are in. To see if the cactus is firm or starting to get squishy where the deflation is happening you could poke it gently with a blunt wooden stick (like a chop stick or something similar).

And just to be sure: the pot it is in has a drainage hole?

Thanks - yep, pretty sure that one has drainage. Some don't, which I know is a no no, but with as dry as things are out here, it doesn't seem like I've had trouble with things drying out completely.

I wonder if I should try to pull it out and look at the roots, which by default involves reporting, given we're late in the season?

I would probably not do that until I had a better idea if I may have been over or underwatering the plant. If the roots are not really the problem disturbing them adds another stressor to the plant. If the plant is still firm (try the poking bit) and feels well rooted (take something like salad tongs and gently grab the plant and see if it moves easily or feels very solidly stuck in the pot) then the roots are unlikely to be the (main) problem. If the plant is squishy and not firmly rooted you might decide to inspect the roots.