Lavandin lavandula x intermedia Seal

Lavandula x Intermedia ‘Seal’ is a highly aromatic evergreen shrub growing 80cm tall, with silver foliage and violet (dark blue) flower spikes held aloft on the top of slender, leafless stems around 30cm long. The main flowering period is in July and August but it will give structure to a garden throughout the year. Lavandins are sterile, so they need to be propagated from cuttings rather than by seed and this means there is very little variation in the characteristics from plant to plant, making it ideal for hedging. A Seal lavender hedge can also provide shelter to other plants. Planting the strongly scented lavandins next to a fruit crop will attract bees and butterflies to pollinate your fruit as well as repelling greenfly. The profuse and highly fragrant flowers are edible but are typically used for pot-pourri rather than cooking because of the highly pungent camphor content. The aroma of a Seal lavender bag will keep for at least two years. Seal and Grosso are particularly noted for their high yields of lavender oil and are favoured cultivars for commercial crops. Arabian Night and Grappenhall have similar characteristics to Seal.

Seal Lavandin will grow best in a sunny position, with well-drained neutral to alkaline soil, with minimal fertility. It is easy to grow and does not generally suffer from any pest or disease attack, and requires very little watering. It will not tolerate having its roots waterlogged so with clay and heavy soils you will need to plant it on a mound or dig in plenty of grit or sharp sand to improve the drainage. Lavandins are also suitable for container planting as long as you ensure the compost is free draining. Potted lavender should only be watered sparingly, just enough to ensure the compost doesn’t completely dry out. Newly planted tender lavenders need light watering for about three weeks, until established. Mature lavenders usually do not need watering but avoid watering your mature lavenders more than once a week, giving the plant just a dash of water, because over-watering is detrimental. Fertilizer isn’t really necessary either but feeding with potash will improve colouration and encourage flowering. If given the right growing conditions a plant will establish a bushy mound in the first year, and reach maturity in four years, with a potential lifespan of approximately 20 years.

Pruning is essential, and Seal Lavandin needs to be cut back in mid September, even if it means sacrificing some late flowers. Hard pruning is beneficial but you must ensure there are at least some small shoots visible below where you cut, even on old woody stems, because without them your lavender will wither. These will grow into a mound of new foliage and possibly a second flowering before overwintering. Seal Lavandin is evergreen and very hardy, to at least -15C, and will cope with most British weather. Pruning for tidying up and shaping is possible in Spring, but only lightly, to avoid the removal of new bud forming shoots.

Lavandula x Intermedia ‘Seal’ is named after The Herb Farm at Seal, near Sevenoaks in Kent, which was established in 1918 by Dorothy Hewer. She was a pioneer in commercial herb growing with crops of peppermint and lavender for oil production, and other herbs that were propagated for culinary and medicinal uses. Dorothy Hewer’s ‘Seal Lavender’ was sold by mail order and through a shop in North Audley Street, London. It was marketed as being the best variety for commercial purposes, for drying and distillation.

Dorothy had previously started a career in teaching but had to abandon it due to a hearing problem. However she took on six students a year at the Herb Farm to pass on her horticultural expertise. One of her students, Madge Hooper, became her secretary and went on to create the Herb Farm at Stoke Lacy in Hertfordshire.

The creation of Seal Lavandin has been attributed to the Herb Farm at Seal, before 1935. However it is worth noting that around 1929 Dorothy received plants from the eminent Maud Grieve. Maud was the author of A Modern Herbal (published 1931), and created the Herb Farm at The Whins Cottage, Chalfont St. Peter, Buckinghamshire, which she ran from 1905 until 1929, when her husband passed away.

Dorothy Hewer also employed Margaret Brownlow, who ran the Seal Herb Farm during the war, and expanded the business. Margaret went on to establish several other herb gardens including nearby at Knole and at Lullingstone and published two books, Herbs and the Fragrant Garden (published 1957) and The Delights of Herb Growing (published 1965). The Herb Farm at Seal was closed in 1968 after Dorothy passed away.

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