im know expert bye any stretch of the imagination but i do know some cacti dont flower more often than every 100 years .

Hi Nosey, I suspect you are referring to the Century Plant (Agave) some of which do take many years to flower. Not true cacti but many people call them that.

If it is a true stem succulent cactus with spines, what shape is it (barrel or cylindrical, tall or squat?) Any chance of a picture and I might be able to say which genus and advise from there?

probably fractal i believe cacti bye nature arnt used to getting lots of water etc and to flower takes exceptional circamstances in the wild . am i wrong in believing there can be big gaps between flowering in true cacti then as id be interested to know ?

It is said that if you want a cacti to flower then you dont water it so then it thinks it is going to die and sends up a flower in order to send out its seed and so keeping the cycle going.

Well, there are so many species and some that are commonly grown actually come from the grasslands of southern Brazil and Northern Argentina and wouldn't thank you one jot for doing this to them in the growing season not to mention the huge group that come from wetter areas to the immediate north of here.

You really can't generalise about so large a group as this though in your defence, most are extremely adaptable plants (unless they belong to various high altitude genera/species). Like virtually all flowering plants (I think) they need Potassium to initiate flower buds to be produced. Do you feed your plants at all?

fair enough i think lol did what to them fractal . i guess i know so little because there not my thing interesting as they are .

Thanks for the debate guys! - I will try to get a pic of the offending item!!