For so long now gardeners, nursery growers and specialist plant breeders have worked tirelessly to ‘improve’ the plant world to suit the tastes of gardeners. From small, fairly simple, flowers breeders have bred a vast and diverse range of Dahlias in shades of most colours, while Agapanthus have gone from a few fairly similar species and forms to an impressive range of dark blues (some almost black) to pale blues, whites and bicolours, tall, medium, short and tiny, variegated and even double flowered. Probably the most iconic plant for most gardeners, the rose, is the one that has changed the most; from scrubland plants with small simple flowers in white, red or yellow, we now have roses in every conceivable colour (except a good blue or green!), with even a choice of how complex you want your double flowers!
At the other end of the scale is one of my favourite plants, Persicaria campanulatum. This species occupies a lovely part of the plant world, what the Scottish woodland gardening specialist Ken Cox calls the ‘aristocratic weeds’. These ‘aristocratic weeds’ are considered by many to be unworthy because they might have a rough appearance, they might spread or seed around a bit, or look superficially like a well known weed. P. campanulatum fits these criteria perfectly!
As a species, P. campanulatum is native to northern India, Nepal, Sikkim, Bhutan, northern parts of Burma and south western parts of China, where it is nearly always found in damp places or scrub, at altitudes between 2,100 and 4,100m (6,890-13,450ft) above sea level (Phillips and Rix, 1993). This altitude has given it good hardiness; probably fine for USDA z7, maybe lower if sheltered or protected by trees overhead. The one thing this species really won’t tolerate is drought during the growing season.
Despite being introduced in 1909 this species has remained pretty much solely in the collections of more adventurous plantspeople and hasn’t really been adopted by the wider gardening world. This is almost certainly down to its ‘aristocratic weed’ looks! Despite the general apathy to the species, on the 5th of October 1920 a plant shown by Messrs B. Ladhams of Southampton, UK, received the Award of Merit (AM) from the Royal Horticultural Society. There is mention of it growing in the Oxford Botanic Gardens and flowering continuously for three months in late summer/autumn of 1920.
In the Gardener’s Chronicle of the 11th of January 1936 a fan of the species wrote an article in the hope of encouraging others to grow it.
“This attractive Himalayan species is fairly common in cultivation, but rarely is it seen to the best advantage. I have often seen it hidden away in some odd corner, regardless of its long flowering period and its autumnal beauty. It is a hardy plant which attains a height of four feet [1.2m] or so, and is therefore a distinct form in this varied genus.”
C.C. Collins, Herne Hill (London), Gardener’s Chronicle, 11th of January 1936
“[Polygonum] campanulatum is very floriferous, the period of flowering lasting from the beginning of July until late autumn, when frosts soon cause both flowers and leaves to drop, but the beauty of this plant is by no means curtailed, as the stems change to a reddish-orange colour, while the thick nodes are almost black, and for this reason alone I consider that it should be prominently placed, as plants which provide such bright autumn colouring are in great demand by all garden lovers.”
I’ll take C.C. Collins at his word about the autumn colour; in my fairly mild area this plant carries on flowering until winter storms knock the stems over, and then we tend to get the frosts later into winter.
With appropriate positioning this is an easy plant to grow in sun or part shade. Firstly let’s bear in mind that it is a Persicaria and, like the majority of the genus, it can squash less boisterous plants so this should be taken into account. That said, if you have a large damp area in the garden then this plant will grow well and give you a large late season alternative to the usual Primulas and Gunneras. While P. campanulatum does spread it creates a clump that is visible all through winter, so control is simply a matter of looking at the clump of distinctive, corrugated leaves at ground level, allowing for the ‘up and out’ habit of the plant and, if necessary, slicing around the clump and removing anything you feel you no longer need. This method also works very well for propagation. You can grow this species perfectly well in ordinary soils too, providing it doesn’t get too dry during the summer, and in fact growing it away from wet soils controls its spread dramatically. I’ve seen this species growing, uncontrolled, in wet conditions and I must say that I would recommend to the absolute majority of gardeners, certainly in areas with higher rainfall, that they grow this species in more ‘ordinary’ conditions!
I’ve never come across this species seeding in any meaningful way, but wouldn’t completely rule it out as a possibility. Readers particularly in those parts of the USA that are prone to invasion by what the rest of us grow as fairly harmless garden plants should probably be very wary with this, and most/all Persicarias (the perpetual flowering over such a long season would make it nearly impossible to even deadhead this species). There are a few clones around, so I guess there is probably some seeding going on somewhere.
P. campanulatum- the straight species has pale pink flowers over a long season.
P. campanulatum ‘Rosenrot’- this is probably the correct name for P. c. roseum and ‘Dark Form’. Exactly as the species but with dark reddish pink flowers. In the same way that the ordinary form would show up well in part shade, so this form might stand out better in a brighter location.
P. campanulatum ‘Southcombe White’- this is probably correctly called ‘alba’, but the Southcombe White name seems to be more popular. Southcombe Nursery was the home of the late Trevor Wood, a plantsman and all round nice guy; he was fairly popular in plant circles, particularly in the South West of the UK, and this might be a factor in how the ‘Southcombe’ name has stuck.
P. campanulatum ‘Madame Jigard’- I think this is the form I saw at Knoll Gardens, the home of UK grass expert Neil Lucas, several years ago. Pretty much as per the straight species, but this form has a rather striking dark red stripe along the midrib of each leaf. Put it in a brighter spot so the foliage stands out!
Overall I really like this species. It has a charm, a personality to it that can be lacking in the more contrived garden plants. Despite growing to a decent size it’s not a particularly ‘overt’ plant, but instead it has a quiet charm that is sure to delight those of us who enjoy a more subtle style of gardening.