Do they need it? If you mean new planted it depends, if you mean a few years old, it won't hurt. Also what shrubs?

I wouldn't bother - if you want to put something to feed them, use fish, blood and bone instead, fork it in lightly round the plants, or if you're not bothered about being organic, use Growmore. Bonemeal takes years to bio degrade and doesn't provide any particularly useful nutrients because it takes so long.