Be prepared, on entering this cool world. Unless you have chanced upon one of those glorious mistakes of an English winter - a mild, clear pearl of a day - wrap up warm and wear good walking shoes. There is nothing worse than trying to have a good time in a state of acute physical discomfort. At Polesden Lacey, one of several National Trust gardens that are open through the winter, it seems the statues have themselves taken this advice and are covered in custom-made protective coats against the cold. The Edwardian gardens, along with the house and estate, were left to the National Trust in 1942 by the society hostess Mrs Ronnie Greville. She is buried outside the walled rose garden and her dogs are in a little cemetery of their own. A small winter garden is sheltered by three Persian ironwood trees and, in early February, is a carpet of bright yellow aconites. There are excellent walks in the grounds, from the gentle Admiral's walk to the wooded hillside beyond where hidden in the trees is Tanners Hatch, a wonderfully dingle-dell youth hostel from which, any minute, you expect Hansel and Gretel to emerge.
Alice might well emerge from the wonderland of yew topiary at Blickling Hall near Norwich, which even has a cut hedge in the form of a grand piano. Two monumental yew hedges, 370ft long, 20ft high and 15ft wide, line the entrance to the Jacobean mansion. More hedges are at Ickworth Park and Garden in Suffolk, which has a national col- lection of box, unusual varieties of privet and, hidden amongst the trees in the Silver Garden, large, hexagonal stones poached from the Giant's Causeway.
For fine conifers visit Killerton, where the common Hinoki cypress and Japanese red cedar grow alongside rarer members of the family: the incense cedar and Japanese umbrella pine. These 17 acres of garden, near Exeter in Devon, were first laid out in 1777 by Sir Thomas Acland and his agent John Veitch when the house was rebuilt. Veitch went on to found a famous firm of nurserymen, who searched the world for new plant species and sent many of them home to Killerton. Earlier this century the tradition was continued, with Sir Francis Acland adding new species of rhododendron - floral trophies from Captain Kingdon-Ward's expeditions to the Himalayas. From still further afield, huge tree ferns from New Zealand show their fronds in the fernery at Tatton Park in Cheshire. The 60 acres include Italian and Japanese gardens, an arboretum, a pinetum, an orangery and winter-flowering shrubs.
If you're braving the chills of Northumberland, flowers of daphne, mahonia, viburnum and hellebore bring interest to the 18th-century walled garden at Wallington, near Morpeth. There is also a fine winter garden at Belsay Hall near Newcastle, though Belsay may be best known for its romantic quarry garden leading to a 14th-century castle in the grounds. Forget the TV and warm sofa, and take a walk on the winter side.
The other side of winter? Spring, with snowdrops as early emblems of its emergence. In their honour, various National Trust properties that are normally closed during the winter have special "snowdrop openings". Two of these open their gates (for a few hours only) on Sunday, 23 February: Belton House, in Lincolnshire (which featured in the recent BBC adaptation of Pride and Prejudice) and Moseley Old Hall near Wolverhampton (which sheltered Charles II after his disastrous defeat at Worcester in 1651).
But snowdrop specialists might prefer to head for Anglesey Abbey near Cambridge where more than 50 varieties "come to light unexpectedly", according to National Trust files, and can be witnessed on three consecutive weekends in February. The truth is out there. Renewal is on its way, even in the bleak midwinter.
English Heritage: Belsay Hall (01661 881636). National Trust: Stourhead (01747 841152); Polesden Lacey (01372 458203); Blickling Hall (01263 733084); Ickworth (01284 735270); Killerton (01392 881345); Tatton Park 01565 750250); Wallington (01670 774283); Belton (01476 566116); Moseley (01902 782808); Anglesey (01223 811200). Youth Hostel: Tanners Hatch (01372 452528).