Question
I've had a cactus for about a year and it is very, very slowly  shriveling up. Many of the needles have gone from black to greay, as well.

I don't know what type of cactus it is. It's about 9"-12" tall with a tubular, not fan-shaped body.

It's in a clay pot that should be a fine fit - 6-7" at the top and maybe 3" at the bottom. The soil is a standard suculunt potting mix that I got from a gardening store.

I water it infrequently, maybe once every 2 months with a shot glass full of water.

It's on a north-eastern facing window sill and gets a ton of light during the day. It is a little hot over there, but also cool at night.

Don't want to over water and don't think I'm under watering. Lots of light, and the soil seems like it should be right. So, what's up with my emaciated cactus?

Thanks for the tips!
E-

Answer
Eric,

Actually, you are severely under watering it. In general, most cacti need to be watered well (soak the soil), then left to dry out. In the summer this cycle might only be a week between watering (if your plant is outside) to every 2 weeks if it is indoors. In winter the cycle maybe once per month.

Water it well and watch, hopefully there is not too much root damage (roots die off in a severely arid environment). Your plant should start returning to normal within a few days. If not, do not water until the soil is dry, because if you over water, it will rot. Hope this helps.

Sincerely,

Greg