cutting back red tips

I have 12 red tips that are too large. I would like to cut them back.* Anyone have suggestions on how much I can cut and when?* I live in Ms

Hi Irene,

Photinia fraserii aka 'Red Tips' can be sheared resulting in a more formal look or hand pruned for a more informal look.* They are often pruned twice a year.* If you wait until June you will get to appreciate the red tips.* Prune again in September if you need to.

This picture shows one sheared improperly.* They should be wider at the bottom and not at the top.*
http://davesgarden.com/guides/pf/showimage/40568/

Here's an example of a better pruned hedge.
http://davesgarden.com/guides/pf/showimage/192469/

They can tolerate severe pruning but look unsightly until they fill in again.* Do you need sites on how to prune?

Newt