Unlike his colleagues, the foxglove beard-tongue is quite reliably hardy and with its high tolerance it is a plant for almost all cases.
Profile of foxglove beard-tongue:
Scientific name: Penstemon digitalis
Plant family: figwort family (Scrophulariaceae)
Other names: foxglove beardtongue, talus slope penstemon, white beardtongue
Sowing time: inhouse in March and then plant outside in May
Planting time: spring
Flowering period: July to August
Soil quality: sandy to loamy, nutrient rich, humus rich
These information are for temperate climate!
Use in: flower beds, bouquets, single position, group planting, borders, flower garden, prairie garden
Winter hardiness: hardy, USDA Plant Hardiness Zones: 6 (-20,5 °C / -5 °F)
Bee and insect friendly: Yes
Plant characteristics and classification of foxglove beard-tongue
Plant order, origin and occurrence of foxglove beard-tongue
The genus of beardtongues, botanically Penstemon, belonging to the figwort family (Scrophulariaceae), consists of more than 250, partly herbaceous, partly woody species. They all come from North to Central America – including the foxglove beard-tongue (Penstemon digitalis), which grows wild in the entire eastern part of the USA. It prefers to appear there in herbaceous corridors, prairies, sparse forests, at forest edges and clearings, but is extremely adaptable to a wide variety of locations. At the natural site of several years, beardtongues are generally traded mostly as short-lived seasonal flowers, since they are not always hardy everywhere. However, the foxglove beard-tongue is a very robust species.
Characteristics of foxglove beard-tongue
Penstemon digitalis is a herbaceous, perennial and cluster forming perennial that grows to a height of 60 to 100 centimeters (24 to 40 in). Depending on the climate and location, the plant is summer- or winter green. In spring, it sprouts with short rhizomes from the rootstock.
The ovate to broadly lanceolate, smooth-edged base leaves of the wild species are together in one or more leaf rosettes. They can grow up to 15 centimeters (6 in) long and 6 centimeters (2.4 in) wide. The leaves of the flower stems are narrower, lighter and often finely serrated. Towards autumn, the leaves turn into a bright purple, especially in sunny locations.
Between July and August the foxglove beard-tongue opens its white to pale pink, non-scented tubular flowers, which consisting of a three-lobed lower lip and a two-lobed upper lip. They are arranged in panicles at the end of the flower shoots, which are up to 100 centimeters (40 in) long. Each panicle blooms for about a month.
When the stem dries, the pollinated flowers form several oval seed pods, each of which contains numerous gray seeds. Later the shoot bends and spreads the ripe seeds.
Foxglove beard-tongue – cultivation and care
Foxglove beard-tongue is quite tolerant of the location, but prefers full sun to at most partial shade and lots of warmth. Especially in areas where there is a risk of black frosts, the plants are grateful for a sheltered place.
Relatively nutritious and humus-rich, not too light, but nevertheless permeable, sandy-loamy soils are ideal. If the subsoil is too heavy and compacted, the plants are rather short-lived due to too much moisture. The pH should be in the slightly acidic to neutral range.
It is best to plant in the bed in spring. Alternatively, you can grow the foxglove beard-tongue from seeds in the house in March and then plant it out in May. The plants enjoy a soil that is well prepared with humus or compost. The planting distance should be about 40 centimeters (16 in).
In very hot and very dry summers, the plants are grateful for occasional watering.
At the beginning of the growing season in spring, compost or a conventional complete fertilizer should be applied. After that, fertilization is no longer necessary.
After flowering in autumn, the stems can be cut back to the ground. Some stems can be left as frost protection. In addition, the perennial should be covered with some brushwood over the winter.
The foxglove beard-tongue is easy to care for. If you like, you can always remove faded flowers from the panicles to keep the bloom a little longer. The shoots are quite stable.
The wild species can be propagated without problems by sowing in early spring (indoors), but cultivations are not true to variety when sowing. It is better to propagate them by cuttings (in early summer) or by dividing them (in spring).
Diseases and pests
Unlike other beardtongues, snails are usually not a problem for Penstemon digitalis. Powdery mildew or aphids can occasionally appear, especially when the plants are stressed by incorrect site conditions or long periods of drought.
The foxglove beard-tongue is considered a hardy species, but it should be covered with brushwood in rough regions.
Use in the garden
You can combine Penstemon digitalis in herbaceous beds, prairie garden or on the edges of trees, for example with baby’s breath (Gypsophila), Canterbury bells (Campanula), widow flowers (Knautia macedonica), meadow phlox (Phlox maculata), blazing star (Liatris), wild indigo (Baptisia) or fountain grasses (Baptis Pennisetum). The flowering panicles are also a great and durable cut flower and decorative in a vase.
The wild species can hardly be found in shops, but instead the 80 to 100 centimeters (32 to 40 in) high variety ‘Husker’s Red’. It has bronze-purple foliage and white-purple flowers. Later, the dark seed heads are a decorative element. The rarely offered cultivations ‘Precious Gem’ (early blooming, light pink, 70 centimeters (28 in) high), ‘Joke’ (late blooming, pink, with dark wine-red stems and green-red leaves, 100 centimeters (40 in) high), ‘Mystica’ (delicate- lavender purple flowers, early blooming, 75 centimeters (30 in) high) or ‘Dark Towers’ (soft pink flower, about 80 centimeters (32 in) high), come with dark leaves as well.