Ulmus 'New Horizon' - Cultivation

Cultivation

The tree has not been an unqualified success. In the elm trials conducted by the University of Minnesota, 'New Horizon' was found to need relatively high levels of maintenance, largely owing to its predilection for co-dominant leaders and heavy side branches. In the Netherlands, removal of sideshoots from the lower trunk was found to be necessary twice a year. In trials in eastern Arizona it often exhibited > 25% crown dieback over winter and a very high level of leaf scorch in summer. The tree is currently being evaluated in the National Elm Trial coordinated by Colorado State University.

'New Horizon' was introduced to Europe by the Conrad Appel nursery (ceased trading 2005) in Darmstadt, Germany, which propagated the tree under licence as one of the hybrid elms offered in the Resista series ; the tree is currently propagated by Eisele GmbH. Introduced to the UK, 'New Horizon' was named 'Best New Plant Variety' by Horticulture Week in 2005, however, an assessment by Butterfly Conservation found its growth on heavy, poorly-drained ground negligible. Nevertheless, the tree has tolerated flooding, by both freshwater in England, and seawater along the Baltic coast in Germany . Trees at exposed sites in Hampshire exhibited much the same degree of dieback experienced in the Arizona trials despite the extreme differences in climate. However no losses have been sustained, and in sheltered conditions on deep loam over chalk, 'New Horizon' grew healthily if relatively slowly, increasing in height by approximately 50 cm per annum, less than half the speed of the Dutch hybrids such as 'Dodoens' planted with it. The trees in the English trials first flowered aged 10 years, in late March.

In 2004, 80 trees were donated to the Greater London Council as part of the grower's European Elm City promotion; similar gifts were also made to Belfast, Cardiff (Pontcanna Park), and Hamburg (the central City Park). In 2010, 100 trees were planted in the London borough of Enfield to aid and abet the conservation of the White-letter Hairstreak Satyrium w-album. Another hundred have been included in the tree planting at the Olympic Park. Specimens have also been planted in various parts of Edinburgh, such as Castle Terrace, the Meadows and Inverleith Park.