feeding red robin

sorry what is r.r.?

I would assume Red Robin is Photinia. I wouldn't suggest feeding it in the winter as it will be dormant and not needing nutrients. Plants in general only need nutrients to make growth when they are actually in growth, so I would wait until the spring comes before you feed it, then some fertilizer will do it plenty of good.

Agree with Jonathan - rake in Growmore round the base of the plants in March, if you live in the UK. On the subject of pruning, as you have them in the row, I'll assume you're creating a hedge - it's a bit late, you'd normally cut the hedge in about May and then again in August, so if you want to, take about six inches off the tops immediately, but don't leave it a couple of weeks.