Grow: Cunning foxglove schemes

Fairy thimbles, fairy gloves, witches’ bells . . . whatever name you might know it by, the lofty purple flower spires of our native foxglove are one of the joys of midsummer, producing a flickering haze of nectar-rich purple bells in woodland, damp hedgerows and roadsides for weeks on end.

As a small child, I imagined that each of those freckled, tubular purple blooms, with its cinched-in waist and long, hooped skirt, was a dress fit for a fairy queen, and indeed another of the plant’s common names is “fairy’s petticoat”.

Its Latin name, Digitalis purpurea, is slightly more prosaic. Quite simply, it means fingerlike, a reference to the ease with which you can slip the silky flower over your finger, just like a thimble.

Although the common foxglove is a native wildflower, the plant has made itself at home in many Irish gardens, where it self-seeds with happy abandon.

Most gardeners welcome it, and with good reason. Those long-lasting, sculptural flower spires, which rise in early summer from a low-growing, overwintering rosette of leaves, add a strong vertical accent to a flower border and have a charm that associates well with many other summer-flowering plants, including delphiniums, perennial geraniums, astrantia, catmint, sweet William and sweet rocket.

That accent is also provided by the many different garden varieties or forms of this pioneering native species, all of which enjoy the same growing conditions – full sun or light shade and a damp, humus-rich soil – and which can be very easily grown from seed sown at this time of year to flower the following summer.

The enduring classic is the white-flowered foxglove, Digitalis purpurea f. albiflora, but there’s an increasing range of varieties available with flowers in hues of apricot, pink, cream and yellow.

Many have decoratively speckled throat-markings such as the popular ‘Pam’s Choice’, whose pale tubular blooms are freckled inside with dark maroon. For those who like that sort of thing (I confess I don’t), ‘Pam’s Split’ has flowers of similar colouring, but with petals split along their length.

Other varieties are more compact than the species; an example is Digitalis ‘Primrose Carousel’, discovered by chance growing in a garden in Suffolk. It produces its pale yellow, claret-speckled flowers in dense clusters along the 30cm tall stems.

A few, such as the compact ‘Foxy’. will even flower the same year from an early spring sowing. Like all foxgloves, their tubular flowers are exceptionally rich in sweet nectar, making them irresistible to long-tongued bees and many other pollinating insects.

But Digitalis purpurea, which is native to much of western Europe, is just one of many different species belonging to this diverse genus of plants. It's also the only one that's classed as biennial; in other words, the only foxglove species that flowers in its second year and then dies.

Perennial species also suitable for an Irish garden include the rusty-gold flowered Digitalis ferruginea, a short-lived, hardy foxglove that prefers full sun and a drier soil than the Irish native species. Its tall, burnished flowers appear from June-August and look right at home in a prairie-style planting scheme.

Grow this aristocratic foxglove alongside tall grasses such as Stipa gigantea or Calamagrostis ‘Karl Foerster’, and threaded through other long-flowering perennials such as Helenium ‘Waltraut’, Hemerocallis ‘Stafford’ and the yellow ox-eye, Buphthalmum salicifolium, all of whose fiery hues will complement its elegant flower spires.

Other perennial species of foxglove with flowers in shades of milk-chocolate and honey brown include the compact Digitalis parviflora (60-90cm). A hardy, long-lived plant that is native to Spain, it also does best in full sun, and produces architectural spikes of chocolate-coloured flowers from June -July.

Yet another very decorative perennial species that enjoys similar growing conditions is Digitalis stewartii, whose dusty golden-orange flowers appear on tall stems (1-5-1.8m high) from June-July.

If you don't want to grow these from seed, the excellent Mount Venus Nursery (mountvenusnursery.com) in Dublin stocks many of the more unusual foxgloves, including Digitalis x mertonensis, another short-lived perennial with tall spires that are the colour of crushed strawberries. They appear from May-June.

A hybrid species, it’s the result of a cross between our native Digitalis purpurea and Digitalis grandiflora, an Eastern European species with pale yellow flowers.

Many other unusual species, varieties and hybrids of foxglove are available to order as seed or plug plants from The Botanic Nursery in Wiltshire in the UK (thebotanicnursery.co.uk).

Other recommended seed suppliers include Thompson & Morgan (from mrmiddleton.com), Westport-based Seedaholic (seedaholic.com) and the UK-based Sarah Raven (sarahraven.com). Order seed now to sow within the next few weeks.

While it’s entirely possible to sow direct outdoors into a well-prepared seed-bed for transplanting later in the year, I prefer to surface-sow into seed trays, before pricking the individual seedlings out into modules.

That way, you can ensure that the tiny, feather-light seeds won’t be blown away by the wind, and can keep vulnerable seedlings well watered and protected from slugs and snails.

Transplanted into their final positions in autumn, they’ll flower the following year.

If you allow the plants to set seed rather than deadheading them, they’ll also seed themselves profusely around the garden. Digitalis is a famously promiscuous genus, so who knows what new and eminently garden-worthy varieties of foxglove might appear among the resulting offspring.