Dunham Massey planned the new seven acre garden with help from plantsman Roy Lancaster, following mounting demand from visitors for the site to open through winter.
A total of 200,000 bulbs have been planted in the garden – which opened today (2 November) – along with new trees and winter shrubs.
Plants used include Iris, Cornus, Daphne, Sarcococca and Viburnum.
Trees sourced from Barcham Trees and Thornhayes Nursery included Callicarpa, Malus, Betula and Prunus.
Dunham Massey's head gardener Damian Harris explained: "We were getting increasing visitor feedback that they wanted something in this area open through the winter."
The area covered by the new winter garden was originally part of Dunham's deer park, but was turned into a paddock for ponies in the early 20th century.
Clearing work started in June 2007 and lasted six months. The original woodland feel of the area was maintained by keeping some of the large oak and beech trees, several species of rhododendrons, pieris, bluebells, azaleas and hollies.
In addition, 400m of new pathways were laid.
Roy Lancaster first visited the site in autumn 2007 and worked closely with Dunham Massey's own five-strong team of gardeners on the project
Harris added: "We walked around with Roy Lancaster and brainstormed ideas. All the plant lists were sent to him and he made numerous changes so we got better varieties and cultivars."
The project cost around £150,000, including a kiosk. Volunteers also helped, and the National Trust site now has 25 regular volunteers, up from seven.
The gardens will now be open 364 days a year. They previously closed on 1 November until March.
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