Any general liquid feed will do. I use tomato fertiliser, because it's good for helping plants to flower.

Thank you hywel that's great can I just ask is miricle grow which I use for my HSE plants OK as well ...and how much should I give and how many times like once a week ? Thank you

Miracle Grow is a balanced fertiliser with trace elements so it will be ok for your cactus. Just follow the instructions on the box. From memory I think you use one scoop of the small measure that comes in the box to 1 litre of water.

Don't feed them too often. About twice or three times during the spring and summer is enough.
If you give them too much feed they will develop soft growth, which may be prone to rotting.

If they've been in the same compost for a very long time, as you say, then maybe they could do with repotting.

I have had my cactus plants for years and have never fed them. Some flower every year. All I do is water them once a month from March to October and leave then dry in the winter. They seem to thrive.

Thank you for all advice much appreciated ...is it OK to repot them now they are growing this time of year please ...:-) ☺

This is the best time to repot them.

As Johnp58 said, he's never fed his cacti and they're thriving, and I seldom feed mine. They are also thriving ... which goes to show they don't need much feeding.

The "forest ones" ie the Christmas cactus varieties, are epiphytes, which means they grow on trees like orchids, in the leaf litter that collects in angles of branches etc. (Which is why you use ordinary potting compost for them rather than special cactus compost) So they get very little food naturally. Some of them will put out little white aerial roots to get what they can from the air as well! I repot mine only when they start to look a bit unhappy or when the pot is obviously too full, and only feed them once in the spring after flowering. They don't look lush and green but they flower very well. You can depend on Hywel's advice, he has a wonderful healthy collection.

Hi folks thank you for your advice my cactus has flowers again not many tho but the leaves look very sad bit shriveld so to speak I am going to repot it in ordinary compost and hope it will live if had it many years but in same smallish pot ..