Lamb, John George Dalkeith ('Keith') (1919–2011), horticultural scientist and plantsman, was born on 19 August 1919 in Dublin, the younger son of John Lamb, who had been a doctor in the British army, and his wife Constance (née Johnston). Constance's father, also a doctor, was a first cousin of George Bernard Shaw (qv), and her grandfather Charles Bolton Johnston had established and managed Mount Jerome cemetery in Dublin in the early nineteenth century.
Lamb became deaf in childhood, and had to develop proficiency in lip-reading. Educated at Wrekin College, Shropshire, England, he studied agricultural science at the University of Reading. He returned to Ireland to work in horticultural research from 1947, and sought the plant species most suitable for horticultural purposes in An Foras Talúntais/The Agricultural Institute, located at Johnstown Castle, Co. Wexford. At the same time he undertook post-graduate research and was awarded a Ph.D. degree in 1949 by UCD for his thesis, 'The apple in Ireland: its history and varieties'. A monograph with the same title was published in 1951, and was widely used by botanists and horticulturalists. Lamb had travelled throughout the country, sometimes by bicycle when petrol was still rationed after the second world war, collecting and identifying more than fifty local varieties. His collection of heritage apple trees was destroyed in 1970 during building work in what had been Albert College, later to become Dublin City University, but Lamb's expertise on old apple varieties, developed over fifty years, was recognised and honoured when the Lamb–Clarke Historical Irish Apple Collection was inaugurated at UCD in 1999 (Professor E. J. Clarke of UCD had also worked on apple growing). The commercial production of blueberries in Ireland was started after Lamb successfully trialled American high-bush species in the late 1940s.
In 1961 Lamb took up a post at Kinsealy, the Agricultural Institute's north Co. Dublin research centre, during which he developed an international reputation in plant propagation, and co-wrote Nursery stock manual (1975), a standard vade mecum used throughout the industry, revised many times, and still in print after forty years. Lamb retired as senior principal research officer in 1982, and he and his wife went to live again at Woodfield, near Clara, Co. Offaly, the family's ancestral home, where his parents had lived until their deaths in 1959.
There Lamb and his wife developed the existing garden, and he created a second international reputation among gardeners and plantspeople. His collection of alpine plants, displayed to great advantage in specially created raised beds, attracted knowledgeable visitors and horticultural society groups from all over Ireland and around the world. Lamb happily shared specimens of many of the exotic and recherché plants that he persuaded into memorable growth in the woodland garden and other habitats round his home. Several new plants were collected and/or propagated by Lamb, including Prunus x incisa 'Woodfield Cluster', one of his earliest successes; 'Fairy Gold', a daffodil that resulted from a cross in the 1940s and was named in 1998; and a snowdrop, Galanthus 'Castlegar', that he found in the garden of Castlegar House, Co. Roscommon.
A founding member, and afterwards an honorary member, of the Irish Garden Plant Society, he was also president of the Royal Horticultural Society of Ireland (RHSI), an honorary life member of the Royal Dublin Society, a member of the International Plant Propagators' Society, and a recorder of new native plant finds for Offaly for the Botanic Society of the British Isles. Co-author of Peat in horticulture (1982), he understood the value of peat in the garden and the importance of Irish bogs in the environment and ecosystem, and became an enthusiastic supporter of the Irish Peatland Conservation Council. In 1982 he was awarded the RHSI medal of honour, and was also recipient of the Institute of Horticulture award (1997), the Euro-Toques award of merit (2002) and the Kildare Medal (2007). He and Woodfield featured in an instalment of the RTÉ programme A growing obsession in 1987.
Lamb's expertise in plant identification and in horticulture led to a number of articles in specialist and other journals, the last in 2010, when he was 90. In 1995 the National Botanic Gardens published A history of gardening in Ireland, co-written by Lamb and Patrick Bowe; it marked the bicentenary of the Botanic Gardens, and collected a wealth of information about Irish gardens generally.
Lamb raised a pink camellia in his garden at Malahide, which was given the name C. reticulata 'Helen Lamb', in honour of his wife, Helen (1917–2011). They married on 10 May 1952 in St Michan's church, Dublin. Keith's helpmate and support for fifty-nine years, Helen was a daughter of Theodore Cronhelm Tobias, a Dublin barrister. She was a scholar of TCD, a classicist and, before her marriage, headmistress of Hillcourt School, Dún Laoghaire; her poetry and letters to the editor frequently appeared in the Irish Times. Keith Lamb died on 27 January 2011, and Helen nineteen days later; they were buried together in St Brigid's church, Clara. They were survived by two daughters and a son.