What's wrong with my alpines?

Hi, I am a very novice gardener but since moving house we now have a very established garden of mainly shrubs and conifers. I have attempted to redevelop a rockery area but as soon as i plant anything they seem to slowly wither away.

I did have a small conifer which has now been removed as it was overtaking the space. Could this have been removing the goodness from the soil? What do I need to add to help the alpines grow now or should I just start from scratch again?

So deflating seeing the plants fade away yet see them growing wildly around the village.

Thanks

 

whats your soil like? sandy? when did you plant them and when did they fade away?