Pruning Photinia

We planted photinia along our fence 3 years ago. When I purchased the bushes, I asked the nursery employee when they need to be pruned. He said to wait until they get to be the height we want, and then prune and shape them. Since then, I have read that photinia should be pruned from the beginning to form a hedge otherwise they will develop long stalks of bare branches. This is now happening on some of my bushes.

I want a hedge - how should I prune them? Have I waited too long?

Usually any plant that you intend to grow as a hedge needs to have its top pinched out at an early stage as soon as its has become established,it will then start to grow sideshoots that can then be pinched out again,this will ensure it has foliage right from the bottom,Im not familiar with using Photinia as a hedge but you should cut of its tops immediately,and see if it starts producing sideshoots from lower down .....

Just wondering when they can be pruned?

Prune at the right time so the new growth won't get killed by frost. If you are in a zone where spring comes late, then hold off until mid spring. Also, do not prune too late into the fall. This would encourage new growth just in time to get hit by frost.

In the mildest zones you could prune over a much wider window of time.

Note that pruning when they are budding up to flower will almost always cut off that year's flower crop.

I wouldn't worry too much-I had a photinia hedge, it was growing about 8 feet a year, and clearly wanted to be forest trees. I cut back one side and it sprouted out low and filled in. Last year I finally cut it down-now it is sprouting up from the roots!
Moral of the story-try pruning now and see what happens-you probably can't do permanent damage to such a vigorous plant..

Dont know how long the hedge area is BUT if you need the lower part to thicken out, try cut several branches at the lower part, meantime NIP out ALL the growing tips from every other branches, this will encourage new side shoots that will grow on to withstand any colder winter weather should you get that, the following year, do the same snipping lower down the rest of the stems that were left uncut from last year.
It's probably a boring task to do BUT, sometime we need to do boring for a beautiful end result.

Also as the hedge is now in situ 3 years, make sure you keep the planting soil free from weeds AND along the whole line of soil add handful of a slow release fertiliser, Non chemical for me, the best is Blood-Fish-Bonemeal, But chicken pellets are great too, just make sure you fork them into the soil or you might be surprised at the type of visitors you might find licking the soil LOL.
I do most of my pruning early spring, this allows the new shoots time to grow on, I would only prune late season (Autumn) IF there was damage needing removed, or something was endangering other plants.
After 3 years in your garden environment, I would not expect any real damage no mater when you pruned BUT as mentioned by others above, IF you do have to prune later spring when there are nice fat flowering buds, you will obviously loose these flowers for that yea, some people would say, get rid of the flowers as they dont like the smell, I'm one of those folks BUT I would prune early spring (frost free) as the red new growth is what we grow them for here.UK.

There are several type of the Photinia family, some grow into tree's if left, some are meant for hedging and others are for tall hedging grown as a screen, so maybe IF you went into Garden centre with the full name of the Photinia you have, then you would get m exacting pruning info that is relevant to your type.
Hope this helps you out some and the hedge brings you years of joy.
Best Regards.
WeeNel.