page_title: Elm
section_title: Propagation
hierarchical_section_title: Elm / Propagation
caption_attribution_description: English: Photo of a rooted cutting of Ulmus laevis. Photo taken by author, July 2008
context_page_description: Elms are deciduous and semi-deciduous trees comprising the flowering plant genus Ulmus in the plant family Ulmaceae. The genus first appeared in the Miocene geological period about 20 million years ago, originating in what is now central Asia. These trees flourished and spread over most of the Northern Hemisphere, inhabiting the temperate and tropical-montane regions of North America and Eurasia, presently ranging southward in the Middle East to Lebanon, and Israel, and across the Equator in the Far East into Indonesia.
  Elms are components of many kinds of natural forests. Moreover, during the 19th and early 20th centuries many species and cultivars were also planted as ornamental street, garden, and park trees in Europe, North America, and parts of the Southern Hemisphere, notably Australasia. Some individual elms reached great size and age. However, in recent decades, most mature elms of European or North American origin have died from Dutch elm disease, caused by a microfungus dispersed by bark beetles. In response, disease-resistant cultivars have been developed, capable of restoring the elm to forestry and landscaping.
context_section_description: Elm propagation methods vary according to elm type and location, and the plantsman's needs. Native species may be propagated by seed. In their natural setting native species, such as wych elm and European White Elm in central and northern Europe and field elm in southern Europe, set viable seed in ‘favourable' seasons. Optimal conditions occur after a late warm spring. After pollination, seeds of spring-flowering elms ripen and fall at the start of summer (June); they remain viable for only a few days. They are planted in sandy potting-soil at a depth of one centimetre, and germinate in three weeks. Slow-germinating American Elm will remain dormant until the second season. Seeds from autumn-flowering elms ripen in the Fall and germinate in the spring. Since elms may hybridize within and between species, seed-propagation entails a hybridisation risk. In unfavourable seasons elm seeds are usually sterile. Elms outside their natural range, such as Ulmus procera in England, and elms unable to pollinate because pollen-sources are genetically identical, are sterile and are propagated by vegetative reproduction. Vegetative reproduction is also used to produce genetically identical elms (clones). Methods include the winter transplanting of root-suckers; taking hardwood cuttings from vigorous one-year-old shoots in late winter, taking root-cuttings in early spring; taking softwood cuttings in early summer; grafting; ground and air layering; and micropropagation. A bottom heat of 18 degrees and humid conditions are maintained for hard- and softwood cuttings. The transplanting of root-suckers remains the easiest and commonest propagation-method for European field elm and its hybrids. For 'specimen' urban elms, grafting to wych-elm root-stock may be used to eliminate suckering or to ensure stronger root-growth. The mutant-elm cultivars are usually grafted, the ‘weeping' elms 'Camperdown' and 'Horizontalis' at 2–3 m (6 ft 7 in–9 ft 10 in), the dwarf cultivars 'Nana' and 'Jacqueline Hillier' at ground level. Since the Siberian Elm is drought-tolerant, in dry countries new varieties of elm are often root-grafted on this species.
caption: A rooted cutting of European White Elm (July)
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