Published: July 5, 2017
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Posted on 05.07.2017 |
Added in Plant of the Month
Penstemon
As recalled in the well worth a read, ‘Growing Guide to Penstemons’, the founder of what is now ‘Thompson and Morgan’ wrote in 1855 that should he have to pick just two plants to sell, they would be the Penstemon and the Salvia. Yet while Salvias are still very popular, perhaps due to their ease of cultivation and increasing variety, Penstemons have lost some of the lustre that they once held for the Victorians. Yet, in cultivation, the Penstemon is the charming smaller cousin of the foxglove, sharing in a profusion of tubular flowers, but often more delicate, and in my opinion, still deserves as much space in borders as the Salvias.
 Penstemon ‘Andenken an Friedrich Hahn’ |
 Penstemon ‘Rich Ruby’ |
 Penstemon ‘Firebird’ |
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Recently moved to the family Plantaginaceae, which includes many familiar garden plants such as Digitalis, Veronica, Hebe and Linaria, it was an American, Dr John Mitchell who is known to have recorded what would be later known as Penstemon in 1748. This leads to the collection and use of the plants by those other than the Native Americans, who had long used the plant medicinally. Further exploration in the early 19th century led to additional collections and seed was first offered for sale in London by John Fraser in 1813. European breeding of the plant was active by the 1860s, especially in France and England, where larger flowered and brighter varieties began to appear. The Victorians’ excitement for exuberant formal bedding provided an appetite for Penstemon to be developed as bold and bright annual bedding plants. Therefore as the more romantic and informal gardens came into play in the 1890s, despite having the potential to be used as slighter, more elegant perennials in herbaceous borders, the breeding had rendered practically the whole genus redundant.
However and in reflection of new tastes, slowly more delicate varieties with greater persistence were established. This sees to the start of our modern use of Penstemon in borders as free and long flowering elegant structures, that can provide more flowers than a foxglove without the staking demands of plants such as the Delphiniums.
 Penstemon ‘Schoenholzeri’ |
 Penstemon ‘Thorn’ |
 Penstemon kunthii |
In cultivation, Penstemon are generally put into one of two groups, the smaller alpines which prefer free draining soil and tend to be the species available for sale, and the garden herbaceous/sub-shrubs that are more commonly seen in garden centres as cultivars. To grow the garden Penstemon, plant in full sun or partial shade in humus rich, moist, fertile soil. Top dress in Autumn/Spring with a mulch or leaf mould to help feed and maintain water retention in the soil. To encourage a longer flowering season, do not allow to dry out and dead head as the flower spikes go over, to prevent energy being spent on seed production. In late Spring, after risk of any frost has passed, cut back to 20-30cm off the ground, to encourage a better shape and to remove some of the old growth. It is common for Penstemon to be targeted by aphids just before they flower, however the ladybirds and blue tits will usually find them before they become a nuisance.
Penstemon are generally very easy to propagate, take tip cuttings any time from May-October, just below a node, either soft wood or semi-ripe that are 10cm long. Remove the lower two thirds of leaves from each cutting, then use a dibber to create holes about 2cm deep and place the cuttings into these holes and firm in using finger tips. You can put 5-10 cuttings in a 7cm pot, ideally in a mix of 70% coir and 30% perlite. Soak pots in a tray of water for half an hour and then remove and place a plastic bag over the top, or sit in a propagator. Rooting normally occurs within 3 weeks.
Christopher Lloyd noted his enjoyment of Penstemon, despite observing that they last only 3 days as cut flowers, but perhaps this is all the more reason to grow and leave them where both the gardener and bees can enjoy them at their best.
 Bee on Penstemon kunthii |
