Right-o, this is an easy one to answer.
Well, obviously evergreens which have been trimmed to a very neat shape look great when dusted with snow or frost. The photograph is
of Yew (Taxus baccata) but other good species for this effect would be Leylandii, Lonicera nitida, Privet, Portuguese Laurel, Box and, although not a full evergreen, Beech is also very good for a strong, structural hedge
Viburnum tinus which is a winter flowering evergreen the tiny pink bud-like flower clusters are changing into blue-black berries as we speak
Variegated species come into their own adding bright greens, yellows and creams to the winter garden at a time when everything looks rather grey – Oleaster “Gilt Edge” or “Limelight” and Griselinia “Dixon’s Cream” would be good examples of full height species and Euonymus “Emerald and Gold” or “Emerald Queen” for compact hedges
Dogwoods are at their best – Cornus Alba with its red stems (or the slightly more expensive but even brighter red stems of Cornus Sibirica) looks great planted in a drift alongside Cornus Stolonifera with its bright yellow stems – Dogwood is particularly good set against a snowy background.
And give a thought to the birds struggling for food by providing a selection of species with berries – Holly, Pyracantha, Cotoneaster franchetii, Berberis are all good examples or you can see our ultimate guide to hedges with berries for even more fruitful options.