How do I prune a holly to make it bush?

I recently bought a collection of ornamental hollies including ‘Golden van Tol’, ‘Blue Prince’ and others. I noticed that ‘Blue Prince’ has one single long stem. Should I prune it to make it bush out?

The best time to prune hollies is just before the new growth begins in early spring. The blue hollies, Ilex meserveae – developed by crossing I. aquifolium with I. rugosa – are particularly fine with their blue-tinged foliage which burnishes in winter weather.
Your ‘Blue Prince’ would probably produce sideshoots without any prompting from you. However, if you snip out the lead, just cutting away the top twig, sideshoot production is likely to be brought forward. Later, when the hollies are mature, you can prune as much or as little as you like.