Does Buddleia need ericaceous compost

Yes, Buddleia needs the ericaceous type if compost is to be used. The butterfly bush in question numbers among the world's woody plants which favor a more acidic soil -- in this case, pH levels of 5.5 - 6.5 -- even though adequate space and sunlight as well as good drainage will support growth in neutral soils.

Buddleia will grow in any reasonable soil, it is not ericaceous.