[green fingers]

I planted several photinia last year for my son (about 5 ft high each one) should they be pruned?

[Trillium]

Depends on how high and thick you want them in the future. Some careful pruning will help fill them out better and look more natural. This pruning is by cutting a few crowded branches off at the main stem/trunk rather than shearing off into shapes. The result stimulates interior growth at those points. Tip cutting, aka shearing, will give masses of tip growth, look unnatural like a shaving brush and scream "I was pruned by someone who didn't know how".  

[green fingers]

thanks for this, really want them to grow tall as a screen, so will have a look and prune fron main branches