Industry figures have expressed disappointment that the new £650m US embassy in London is set to use trees mainly sourced from outside the UK.
OBO New London Embassy project director Rodney Evans said: "We've tagged trees from Germany and the Netherlands and we're moving forward with the landscaping, though we're not close to planting anything. That will be summer 2016."
A landscape contractor is yet to be appointed, he added. Willerby is rumoured to be frontrunner. BL Harbert is US general contractor and Sir Robert McAlpine is UK subcontractor. Kieran Timberlake is architect.
Evans added: "The trees we needed were not all available in the UK. We needed certain sizes." But HTA chief executive Carol Paris said: "I see no reason why they couldn't be grown in the UK, given relations between the UK and USA."
Majestic Trees managing director Steve McCurdy said: "It's disappointing they never came here, but we are fortunate to quite regularly supply at the US ambassador's residence. My understanding is that the landscape architects have really driven this procurement process."
Barcham Trees sales executive David Johnson added: "You can get 8-9m trees from Majestic, Hillier, Deepdale and Barcham, if we'd been given the time. I'd like to see the (imported trees) on a nursery here for one full season, but I suspect that they won't touch the sides of a UK nursery."
Evans visited Deepdale Trees in the UK and admitted that sourcing all the trees from the UK would have been preferable because it meant "less transportation" and the development is seeking to be carbon neutral. Three-quarters of the trees will come from Van den Berk and von Ehren in Germany.
The embassy will stand at the centre of a 2ha site with a surrounding public park containing a pond, walkways and seating. Evans said security requirements will be achieved through landscape design, such as the pond, low garden walls with bench seating and differences in elevation to create barriers.
The site will also feature six interior gardens with US themes - Pacific Coast, Gulf Coast, Midwest, Potomac, Canyonlands and Mid Atlantic. The procurement of non-tree stock has yet to begin.
A ground-breaking ceremony was held in November 2013 and the project is due to be completed in 2017. The overcrowded Grosvenor Square embassy, which the US still occupies, is now owned by Qatari Diar Real Estate Company.
Tree choice - Suppliers for embassy project
Deepdale Trees, UK
Acer x freemannii Autumn Blaze
Van den Berk Geldern, Germany
Lorenz von Ehren, Maldfeldstr, Germany
Salix alba Lienpde