Kings Landscapes won the £200,000 contract to construct the Andrew Wilson-designed rose garden at the Savill Garden, Surrey.
More than 2,800 roses are set to be planted in the contemporary 3,600sq m garden, which features a raised platform designed to allow visitors to overlook the curving patterns of flowers.
Milton Keynes-based Kings Landscapes started work on site in the summer and managing director David Houghton told HW he expects to be finished by 20 November, two weeks ahead of the 4 December anticipated completion date.
Between two and 10 members of staff have been on site at any time, added Houghton, carrying out work including creating pathways, stripping the old rose soil and swapping with turf soil.
"The whole project has been quite challenging because of the platform and creating the foundations," he explained. "The levels had to be done to the exact millimetre.
"Having the clients on site meant they have been making daily visits - on most commercial work they might only visit once a week."
The design envisages the creation of an intense sensory experience with roses especially chosen for their scent, strong colours and repeat flowering.
Head of the Savill Garden Harvey Stephens said only 27 varieties of roses are being used in the garden.
"It has been quite a tough choice to pull together roses that really do what we want," he said. "We are very optimistic about the project."
The rose planting will be carried out in January by Savill Garden staff, with plants sourced from growers including David Austin Roses and Peter Beales Roses.
The garden is expected to open to the public next summer.