Penstemon Sour Grapes - Beardtongue

The Penstemon 'Sour Grapes' is a herbaceous perennial whose long amethyst flowering evokes that of the foxglove.

This pretty Scrophulariaceae comes from desert areas of North America, such as the southern United States or Mexico. It is also found in the dry mountains of this zone.

It is a semi-evergreen perennial that forms a small bush of 50 cm (20in) in all directions, and its leaves can be alternate, opposite or even sometimes whorled. The flowers appear from July to November. Shaped like oblong bells, they are adorned with the most beautiful amethyst colour with a slightly bluish external base. The throat is white veined with purple. The corolla is inserted into a purple calyx. This asymmetrical corolla comprises two lips: two fused lobes for the upper lip and three for the lower lip.

The name Penstemon comes from the Latin word Penta, meaning five. This uniqueness gives it the appearance of open and painted lips. Its appearance and colour remind us of the foxgloves of our mountains, minus the toxicity. The flowers, measuring 3 to 4 cm (1 to 2in) in length, are arranged in panicles on the upper part of the stem.

The Penstemon Sour Grapes can withstand temperatures down to -7°C (19.4°F). If the winters are harsher, it must be protected by mulching its base. It likes light soils, accepts limestone soils, and as a desert plant, it tolerates drought very well. It should be exposed to the sun or possibly partial shade. Remove the flowers as soon as they fade to promote flower reblooming. Its exceptionally long flowering period allows it to coexist with summer and autumn plants. Consider silver-leaved artemisias and purple Verveine Star Dreams for summer. The Rudbeckia purpurea, Nepeta faassenii Six Hill in lavender blue, and the Liatris spicata will still be present for a colourful Indian summer.

In Native American pharmacopoeia, Penstemons were long used as analgesics to combat toothaches. Their ornamental qualities are now preferred.