Hi, someone gave me quite a big cactus arm that broke off the main plant
about a year ago.

They say it's still possible to plant it and grow it.

Is this true? I've planted arms that have only just dropped off with
considerable success.

I've planted it in cactus compost, I'm just wondering how often I should
water it. And in what quantity. I haven't watered it yet.

Any advice appreciated!

Tom