Certain varieties of Penstemons can bring colour and life to a garden late in the year, says Peter Dowdall
Often overlooked as a flowering perennial, I first fell in love with Penstemons when I saw the variety ‘sour grapes’ as a child. Beautiful tall stems of tubular flowers are produced during late summer and all the way through autumn.
The colour of ‘sour grapes’ is fabulous because it’s a bit different, blue, grey, silver and mauve are all represented in each flower, it’s a bit muted but still fresh and colourful enough to bring life to the garden late in the year.
It will grow to about 70cm in height and a clump will cover about 70cm in diameter. It is evergreen and thus it has a presence in the garden during each of the twelve months, but don’t rely on it as a plant to bring interest or beauty for its foliage during the winter.
In fact, the only problem with these plants, if problem is the right word, is that they can look ungainly and messy once they have finished flowering in early winter.
Feel free to trim dead flowers during the summer and autumn but do not be tempted to cut back Penstemons hard just after flowering, at this time of the year for they will certainly curl up their leaves and die on you, I learned this the hard way.
Far better to give them their annual haircut in mid to late April when the spring is well aired and the temperatures are on the upward trajectory as opposed to facing into the dropping temperatures of winter.
I have also found that they will root quite easily from semi-ripe cuttings taken during the summer. Cut about 10cm of this years growth, the base of the cutting should be on a node as this is where plants store their auxins, the hormone responsible for producing roots.
Remove the bottom sets of leaves and the terminal bud, be it a flower bud or leaf bud so that the cutting only has about two or three leaves.
Dip the base of the cutting in some hormone rooting powder or gel and shake off any excess, you really only need a suggestion of the hormone on the cutting. Insert the cutting into a pot full of a good multi-purpose compost and within a few weeks you should be enjoying freshly growing new plants.
Taking cuttings like this is a great way of bulking up on the numbers, as these Penstemons can be regarded as short lived. I would say that if you get four or five years out of one plant before it dies ,or simply looks too woody and untidy, then that’s about it, so it’s great to have a constant supply of replacements coming along.
I mentioned ‘sour grapes’ but there are loads of varieties with different flower colours to choose from. There are over 280 species producing over 800 cultivars according to the American Penstemon Society.
Yes, there is a society dedicated to this one genus. It’s one of the few plants that’s exclusively native to the Americas, they’re found naturally from the mountains of Guatemala all the way to the Tundra of Alaska and Canada.
Interesting to note however, that much more work has been done in Europe to develop new hybrids over the years than in the US and I’m surprised to see that our friends in the UK haven’t got their own Penstemon Society, bearing in mind that nearly every plant you can think of has a Society in England dedicated to their development and conservation.
Ihave to ask myself from time to time why plant breeders and taxonomists insist on changing plant names.
I understand when some scientific reason has been found to reclassify a particular plant but in the case of P. ‘Andenken en Friedich Hahn’, I’m delighted to say it was renamed in the 1950s to the much easier and more memorable Penstemon ‘Garnet’, a beautiful rich ruby, indeed garnet coloured plant.
The original name was a real mouthful and the renaming proved that there is indeed a lot in a name as this plant only began to enjoy commercial success when renamed.
Apart from ‘sour grapes’ and the renamed ‘Garnet’ every other colour you can think of can also be found in a Penstemon from the beautiful pale pink of ‘Apple Blossom’, the simplicity of ‘White Bedder’ to the much more vivid, nearly electric blue of ‘Heavenly Blue’.
The most commonly available yellow form is the very narrow leaved and low growing P. pinifolius. It’s more of a rockery form and for me not as attractive as the taller varieties as the flowers are smaller and a bit insipid.
All Penstemons like to grow in a good sunny position in a well-drained soil and often the reason that they are short lived as I mentioned above is because of the amount of rainfall we get, particularly during our winters.
© Irish Examiner Ltd. All rights reserved