Bit naughty of the supplier, its a little late for bare root plants... anyway, no don't prune the roots, but tell her to cut the topgrowth down by half after planting - this will encourage new shoots from the base and create a thicker, denser hedge down to ground level. Also soak them well, prior to planting and after planting, given its been so dry, and keep them well watered. Do not prune again this year though....

I agree with everything Bamboo has said. In the past I have stood 'whips' in a bucket of water overnight before planting.

Thank you both very much for these prompt and very helpful replies. My daughter bought her house a couple of months ago and is keen to establish plants friendly to wildlife in her old but empty garden.

Good for her planting a native hedge. There are so many things that live on Hawthorn (without doing too much damage), then you get the lovely blossom and hips too for the birds later in the year. If she can keep it thick rather than tall and spindly she will create nesting for hedge sparrows, Blackbirds, Robins and many more, spindly hedges and trees harbour pigeons - don't I know it?