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Our new borders on the Arboretum Lawn are now into their second full summer and really starting to fill out and mature. Tall spires of pink and white foxgloves (Digitalis purpurea) planted last year are now beginning to flower for the first time and look fantastic in combination with the giant exploded star shaped flowers of Allium christophii.
A native species, the arrival of foxglove flowers for many marks the end of spring and the start of summer. Their individual trumpet shaped flowers certainly are reminiscent of little gloves or mittens but why they should be attributed to foxes is not quite so clear. Richard Mabey suggests in his brilliant Flora Britannica that the names root may be in found in their preference for growing in ‘foxy places’ like the heathlands, steep banks and the edges of acidic woods.
Highly toxic, the foxglove has long been prized for its medicinal value. John Gerard describes its properties as an expectorant (something to loosen mucus!) in his 1597 Herbal: “Fox-glove boiled in water or wine, and drunken, doth cut and consume the thick toughnesse of grosse and slimie flegme and naughty humours; it openeth also the stopping of the liver, spleene, and milt, and of other inward parts.”
However, administration of foxglove for medicinal purposes was often lethal. Commonly used for the treatment of dropsy (swelling of soft tissue) it was extremely unpredictable, sometimes resulting in the dramatic improvement of symptoms but equally as often resulting in death.
It was whilst investigating their use as a treatment for dropsy in the late 18th century, that the botanist and physician William Withering realised the true medicinal value of the foxglove. Withering was a prominent member of Lunar Society of Birmingham, alongside other local luminaries such as Matthew Boulton and Erasmus Darwin, and one-time resident of Edgbaston Hall, now Edgbaston Golf Club – our next-door neighbour!
Critical to his discovery was the realisation that the correct dose of digitoxin and digoxin extracted from the leaves of the foxglove could slow the heartbeat down (too much and it can stop it all together) and is therefore extremely useful in the treatment of heart failure when correctly administered. His work on the species was seminal and his findings are still relevant today continuing to inform contemporary medicinal practice.
To the gardener they are equally as indispensable. Despite growing wild in abundance, they have long been cultivated in gardens, especially white forms that occur less frequently than the more common pink.
We grow several species at Winterbourne alongside the usual Digitalis purpurea. The chocolate foxglove, Digitalis parviflora, is perhaps the most popular among our visitors. It is smaller in every respect, forming dense rosettes of tough, shiny green leaves and flower spikes tightly clustered with rich, chocolatey-brown individual flowers.
Most species are easy to grow from seed, sown thinly on the surface of potting compost, and kept moist until germination occurs. Covering your seed tray with cling film or a sheet of glass is ideal. Once grown they should be planted in a humus rich soil in part-shade, but they will grow almost anywhere, including in full sun and dry-ish spots.
They are short-lived biennials or perennials so often won’t flower in the first year after sowing, and may only last one further year before needing replacing. However, they self-seed freely and will often replace themselves year on year germinating new plants at the base of the mother plant, that can be left and grown in-situ or transplanted elsewhere in the garden.
Garden designers love them. Their strong vertical form is brilliantly architectural yet elegant, and flowering early in the summer makes them a useful staple ingredient at the big garden and flower shows in May and June. You’ll notice that they are often ubiquitous at the RHS Chelsea Flower Show each year.
Try growing them at home alongside other pinks, mauves and purples or contrasting with yellow flowered plants. Late-flowering azaleas and rhododendrons and purple-foliaged plants like the smoke tree, elder or heucheras all make good foils for the foxglove.
Water them well through dry spells and give them a good mulch with homemade compost at the beginning of the spring. Additionally, you should consider removing the whole flower spike after flowering if you don’t want them self-seeding everywhere and to encourage smaller, secondary flower spikes to emerge again form the base.