Kent Alpine Gardener's Diary
This entry: 30 September 2017 by Tim Ingram
'Lavender - Botany & Aroma'. Dr. Simon Charlesworth.
'Lavender - Botany & Aroma' - talk to the East Kent Group of the AGS, 15th September 2017.
Our first talk for the new season in East Kent was from Simon Charlesworth of Downderry Nursery on Lavender. Simon is probably the leading commercial grower of the genus in the UK and holds a National Collection of some 333 cultivars, 24 of the 39 species, and 15 of the 21 subspecies of the genus. More than that though he has also made a wonderful display garden at his nursey near to Hadlow in Kent, and regularly designs Gold Medal exhibits at the RHS Shows, and even at Courson in France where lavender is especially revered and grown. His talk took us through all aspects of the genus from the detail of their origins and distribution, cultivation and breeding and biochemistry and pharmacology/aromatherapy.
The species are typically Mediterranean but until now I didn't realise that they extend quite far south into Africa and across to the Middle East, and even down into India in the case of two species, L.bipinnata and L. gibsonii. Many of course are quite tender and not horticulturally important, but some of the section Pterostoechas from the Macaronesian Islands and N. Africa (Simon mentioned the rare L. aristobracteata from Somalia for example) have fascinating pinnately cut foliage and can make beautiful specimens in pots protected from frost. We have grown L. pinnata in the past, and this is easily raised from and has the loveliest of foliage.
Much more significant though are the garden forms, especially of the hybrid L. x intermedia which combines the best features of L. angustifolia and L. latifolia from S. Europe. The Spanish L. lanata is especially beautiful for its white woolly foliage and strong violet-blue flowers and hybridises with L. angustifolia to give L. x chaytorae and the lovely cultivars, 'Richard Gray' and 'Sawyers'. These are all reasonably hardy to -10°C or below in poor gravelly soils. The more tender L. stoechas and L. dentata are less reliable except in maritime gardens that don't drop below around -5°C in winter, but the former in particular is so distinctive for its colourful sterile bracts like 'rabbit's ears'. We have grown the closely related green lavender, L. viridis, in the past, which is intensely aromatic and thoroughly intriguing for its unique colour.
One archetypal cultivar of lavender is the famous 'Hidcote', which is often incorrectly grown from seed rather than vegetatively. This dates back (I think) from the 1920's and Simon has sourced original correctly identified plants from which to maintain the true form in cultivation. But there are very close, and equally good, more recent cultivars such as 'Imperial Gem'. A nice picture of a range of these lined out at Downderry shows how useful it is to be able to compare and contrast.
The pharmacological and aromatherapy uses of lavender are even more significant than their horticultural uses, particularly in breeding for high quality lavender oil, which Simon is collaborating with British Columbia University amongst others in researching. He also mentioned the herbicidal effect of monoterpenes in lavender foliage, and utilising the great attraction of the flowers to bees as a potential way of increasing local populations of pollinators for commercial orchards (in a similar way as wild flower meadows), by providing a source of pollen and nectar into the summer after the fruit trees have finished flowering.
It is rare to meet someone with such extensive practical and scientific knowledge of a genus of plants such as this, and to have it so clearly and concisely presented. Add to this the fact that lavender must be found in nearly every garden in the country (maybe I exaggerate, but only a little, and Simon mentioned lavender growing successfully in gardens right across the British Isles) and you have a really appealing subject to explore.
(It's a shame that we only had around 17 members come to this our first meeting for 2017/18 in East Kent, and the three other Groups in Kent have similarly limited audiences.The time seems to have come to try and amalgamate and renew the local membership of the AGS in Kent - something that is true across the country as a whole. Hopefully this can happen in the future and enable us to continue attracting such high quality speakers to our meetings and to increase their attraction to gardeners who are not yet members of the AGS. The AGS Shows held at Sutton Valence in the spring and autumn are the perfect focus for keen plants-people in Kent and so in my next entry I aim to look more closely at these, in a similar way to describing the Rocky Flower Show held in the summer at Wimborne and the South-west Show at Rosemoor. These Shows should become much more visible to gardeners if they expect to grow and prosper into the future).