Hartley Magazine

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How to Grow Penstemons

May 2017 - Penstemon heterophyllus with bumble bee copy
Penstemon heterophyllus with bumble bee

Your greenhouse can revolutionise your garden, because it’s possible to grow a whole range of slightly tender plants, because you can raise them from cuttings. Many of these slightly tender plants come into their own from late-summer onwards, so they extend the season right up until winter beckons. This helps late-flowering pollinators (and gardeners)  to survive the bleak winter months ahead. And colours always look better in autumn light, so the garden has a jewel-box, almost decadent quality.

Many of these later flowering plants occur naturally in southern hemisphere countries close to the equator, where days and nights are very evenly balanced. Fuchsias, penstemons and salvias are among them and all peak in autumn. Garden centres stock them in September, when they are full of flower, but if you plant them outside that late in the year they’re almost bound to fail because they won’t have enough time to produce a root system before winter descends.

The time to plant slightly tender things is now is now, so they develop a good root system before winter descends. Fuchsias, penstemons and hardy salvias are left intact over winter, so they can look a little scruffy. If you cut them back in autumn you are likely to lose them in hard winters. Penstemons are cut back to the base in April, and fuchsias and salvias are cut back to the highest buds.

There are 250 species of penstemons, many of them native to Central and North America. Most named penstemons flower between August and October, but species tend to flower earlier. P. heterophyllus, for instance, produces its blue and pink-toned flowers when the roses and peonies are out, juts when most penstemons are putting on leaf.  The best named form of P. heterophyllus is ‘Catherine de la Mare’.

However most named penstemons flower from late summer onwards. Hardiness varies greatly and in my very cold garden one of the most reliable survivors is the rich-red  ‘Andenken an Friedrich Hahn’, still sold under its old name of ‘Garnet’. It’s almost an octogenarian because it was raised in 1918 by a Swiss nurseryman called Hermann Wartmann. Apparently Hahn was an 18th century German astronomer.  Another Swiss breeder Paul Schonholzer (1905-1972 ) used ‘Andenken an Friedrich Hahn’ to breed a ‘Schonholzeri’, a pink-red with very fine foliage also sold as ‘Firebird’. of the two, I prefer ‘Andenken an Friedrich Hahn’ which is an elegant penstemon hardly ever out of flower between July and October.

Alan Bloom (1906 – 2005) of Bressingham Nurseries was one of the first to stock these Swiss-bred penstemons, Alan, who was one of my greatest friends, told me that the names were anglicised because the plants were bulked up after the Second World War and it was thought that English-sounding names would sell better. He disapproved strongly of name changing, I might add!

Penstemons are highly popular garden plants now, but in Victorian times penstemons were used mainly as summer bedding. Their flowers tended to be wide-mouthed and showy, but these bedding varieties didn’t survive in winter. The practice of bedding them out, like petunias or pelargoniums, died out in the 20th century, because large country houses were short of gardening staff due to the two World Wars. By the early 1970s gardeners had largely abandoned growing penstemons

However one Worcestershire man was crossing and hybridising them in his garden on Bredon Hill.  He bred a series named after birds and they include ‘Blackbird’, Raven and the pink and white ‘Osprey’. His name was Ron Sidwell (1909 -1993) and Ron, who was once the Vice Principle of Pershore College, was a plum expert who famously could tell any plum variety by examining the stone. This skill may seem trivial today, but post-war Britain relied on the home-grown plum crop and unscrupulous growers would lie about their varieties in order to get better prices because certain varieties were in higher demand. Court cases relied on Sidwell’s expert opinion when there was dispute.

After the Second World War more plum orchards were needed in the Vale of Evesham, but plum blossom is early and very frost-prone. Sidwell mapped the entire Vale to find the most frost-free places and he put his knowledge to good use and bought a cottage called Bredon Springs in the hamlet of Paris on Bredon Hill in 1948.  It was chosen purely for its clement frost-free position and sloping one and a half acre garden, which he fiulled with Southern hemisphere plants including penstemons.  Sidwell, who had worked as a gardener in his youth, had a fascination for plants from New Zealand, California and Australia. The forward-thinking Sidwell created a wild garden full of interesting species, running it organically on the basis that great diversity would encourage wildlife.

May 2017 - Penstemon Garnet
Penstemon Garnet

Penstemon breeding seems to be a Pershore speciality because many more modern varieties were subsequently raised by Edward Wilson (1948 – 2009) at nearby Pensham. Wilson studied at Pershore College in the late 1960s, when Sidwell was still a living legend, and he gave many of his plants the Pensham prefix. After Edward died his plants were taken over by Hayloft Plants, based near the hamlet of Pensham. They have continued to grow and raise Edward Wilson’s penstemons since his death and they sell a large range of his and other penstemon varieties. ‘Ted’s Purple’ was named after Edward Wilson, a quiet man who I often spoke to on the telephone. Sadly I never met Sidwell or Wilson, although I had the opportunity!

Among my Hayloft Plants favourites are the Dark and Mysterious Collection containing ‘Raven’, ‘Garnet’ and ‘Sour Grapes’, all strong varieties available as grown plants. You can also acquire twelve plug plants costing £1.00 each and grow them on. They also sell Alice Hindley ( a mauve and white) and the dainty ‘Hidcote Pink’, which has wiry stems and small flowers. Both do well for me and persist. Planted now they’ll flower profusely from late-summer onwards and they’ll overwinter. Hayloft also sell salvias and fuchsias.

If you take cuttings, you’ll have masses next year, to please the bees and you!

Taking Cuttings – including penstemons 

Taking cuttings is a really good idea because most penstemons are not long lived. They tend to last four years, before losing vigour,

Cuttings root easily and should be taken between June and August ideally.

Look for semi-ripe wood produced this year. It should feel pliable, but not soft and new. Cut away three to four inch pieces and remove any flower buds.

Trim underneath the leaf node – where the leaves appear – and then reduce any overly large leaves.

Fill half-size sturdy plastic seed trays with coarse horticultural sand ( or grit sand) and plunge the cuttings into the sand so that most of the cutting is submerged.

Pot the cuttings up in gritty compost once they root. If you have cuttings still in trays at the end of August, leave them there until the following spring, pot up and plant out when rooted.

Maintaining your Penstemons

Deadhead to produce more flower.

Cut off any seed heads in autumn, but leave most of the foliage intact over winter.

As soon as your penstemons begin to sprout at the base in spring, cut back hard to the new growth. Mid-April is generally the time.