euphorbias turning yellow

Hello everyone I do hope someone can advise me.I have recently been given a euphorbia wulfenii to commemorate a wedding anniversary but im upset to say i'm having trouble!

I have noticed that the bottom leaves are turing yellow and are dropping rapidly. by admission i am a complete beginner in the garden  but i do know that the soil is alkaline. no one has been able to tell me what feed it needs or when etc not even the gardens where it was purchased!(was a very well known gardens)

I did have a euphorbia portuguese velvet but after three years of no apparant growth the whole plant died and i am at a loss again as to why this is happening. I have always seen these at RHS gardens where they flourish so cant understand why they are not in my garden.I must be doing something wrong but what?

thanks for listening

Is it in a pot or the ground?

These plants are unfussy creatures as far as soil type is concerned as long as its free draining. They hate wet feet. A sunny position is best although light shade will do and they are also free from any pests and diseases that I have read about.

It may very well be hungry, they grow like the clappers once established. Feed it bone-meal after flowering (which should be about now) and cut back flower stems to base and give it time but wear gloves, the sap is an irritant.

the wulfenii is in a pot at the moment but the portuguese velvet was in the ground, both alakali soil. neither has/had ever flowered.

If it is in a pot, are you keeping it adequqtely moist? Pots need regular watering as rain is not enough to water them.

keeping the soil moist  but still no sign of flowers and the leaves are still turning yellow