Help! Sick cactus?

[cazzalepin]

Sick\dying cactus?

DSC_0301 (531x800).jpg (51.91 KiB) Viewed 582 times

Hello. I would really appreciate some advice. I have been given the cactus in the photo to look after for a couple of years. All I was told was to give it 350ml water every week in summer and every 3 weeks in winter and that it is used to being on a sunny window sill. I think it is about 30 years old. At the beginning of May I moved it from such a window sill (where a few small bits had been falling off) to my greenhouse where bigger and bigger bits have since been falling off. I live in Cambridgeshire UK and thought it would like the extra light & heat. As it also looks pot bound to me I have been giving it a bit of BabyBio. Perhaps this is a mistake? Do bits normally fall off? Please can someone tell me if I am doing something wrong and what I should do instead? I would also love to know the name of the cactus if anyone can tell me.
Thanks in advance
Caz

[jmoney]

It does look like it may need a larger pot but other than that I don't know what could be wrong with it. There are also portions of the plant that look etoliated so moving it to a spot with better light exposure was not a bad idea.

[greenknight]

I think it's just too pot bound, bits are dropping off trying to find new places to root.

BabyBio has too much nitrogen, not good for cacti. Need something that has more potash and phosphate than nitrate, and use very light doses.

[cazzalepin]

Thank you for your help. Is it essential to repot or can I somehow manage the cactus in the current pot?

[jmoney]

I'm sure you could probably manage but I'd repot if I were you.

[cazzalepin]

Thanks for the advice. Do you have any tips on how to go about it?! I imagine I would have to break the pot off? and then how to get in into another? What compost to use? Do I need special gloves to handle it?