Regrets, I’ve had a few … but none so profound as for the fatal day on which I gratefully accepted a kind neighbour’s gift of a single plant of Meconopsis cambrica. Up to my oxters (whatever they are) in the stuff today, I marvelled at the foolishness of my distant youth, when – even more ignorant about horticulture than I am today – all I wanted was plants to fill my newly acquired garden, most of which had previously existed as paving and a jerry-built shed, the electric lighting to which was achieved by a cable loosely draped across the said paving, itself so badly laid that the cable mostly sat in pools of water.

Other planting mishaps have been recovered from (eventually). After several years I succeeded in eradicating an infestation of Himalayan or Indian balsam (Impatiens glandulifera) – which again started from one plant, given by a different kind neighbour.

Himalayan balsam, which can grow up to ten feet tall, and especially loves river banks, where it smothers the native plants.

Looking it up just now, I discover that it was named in 1834 by John Forbes Royle, physician and director of the East India Company’s botanic garden in Saharanpur. (I attended a study morning with the esteemed Christine Bartram the other day @CUBotanicGarden: she argued persuasively that Royle was a major changer of the world through his interest in the commercial possibilities of growing plants such as tea, cotton, and cinchona outside their native habitats.)

The flowers are very attractive, though …

The dreaded balsam was introduced into the UK in 1839 as a garden ornamental, just like Japanese knotweed (Fallopia japonica) in 1825; but, unlike Japanese knotweed and indeed my bugbear the Welsh poppy, it’s very shallow-rooted, and persistent yanking up before the 800-odd seeds per plant set (and certainly before they were ripe enough to be catapulted up to 7 meters away) eradicated the beast. These days, you can’t put it in your green bin: I think I probably  composted mine – presumably successfully, as it’s never grown back.

Geranium endressii: over-efficient as ground cover, but not very interesting …

The other plant I currently have it in for is Geranium endressii – again, seemed like a good idea at the time for ground cover, but a complete thug, and, basically, pretty boring. This autumn, I’m going to dig over instead of just mulching, and yank out as many roots as I can find, while trying not to disturb the embedded bulbs – a fairly hopeless task, admittedly …

The most familiar flower colour of the Welsh poppy.

But back to the Welsh poppy. They are lovely and springlike in spring – especially when nodding above (also self-seeded) forget-me-not – and come in shades from deep orange to pale yellow: but they get everywhere, and seed so rapidly that I have this year’s second generation flowering at the moment, and yet more seedlings sprouting all over the place. Moreover, they are perennials, with a deep, carrot-like root which, once established, is difficult to pull out without breaking (especially from the crevices with minimal soil which it especially likes to colonise), and which of course regrow enthusiastically.

Redouté’s 1833 drawing of Papaver cambricum.

Named Papaver cambricum by Linnaeus (1753), it is endemic to large areas of western Europe, but has, as they say, become widely naturalised outside its native (hilly, mountainous) habitat – you’re telling me.

Orange variants are common.

I used frequently to bemoan the fact that the only Meconopsis I could grow was one I didn’t particularly want, but I’ve recently discovered that although one Louis Guillaume Alexandre Viguier of Montpellier (1790–1867) reclassified the plant as Meconopsis cambrica in 1814, on the basis of a different arrangement of the stigmas and style from that of the Papavera, everything went into reverse in 2011, when it was demonstrated on the basis of DNA evidence that in fact the Welsh poppy is a poppy after all, and not closely related to all the glorious Meconopsis species subsequently added to the genus by Far Eastern plant hunters.

Meconopsis ‘Lingholm’ at Chelsea this year.

The most striking thing about the Welsh poppy, apart from its flowers, is the superb architecture of the seed pods, which means that if you leave it too late (as I always do, somehow) to deadhead them, the mere attempt to cut off the stems or uproot the plant results in spectacular albeit unintended sowing.

Meconopsis cambrica seed pods and seed. (Credit: Roger Culos)

I’ve never seen the plants growing in the wild in East Anglia – though what I take to be garden escapees are frequent in gravel or poor soil near houses and along railway tracks. I take it that they flourish in my garden because, with poor soil, not much direct sunlight, and many crevices to get stuck into, it reminds them of their rocky mountain homes. But the most infuriating thing about these lovely but somewhat overwhelming beauties is that they never, ever, get eaten by slugs and snails.

Caroline