The hogweed have pushed their heads above the meadows and in the rough places where they have taken their hold. Heracleum sphondylium is a brute if it has the conditions it favours and will soar to two metres to eclipse less vigorous companions. We see this happening here on newly disturbed ground and in the rich soils by the ditch, but in the higher, drier meadows it is kept in check and steps nimbly enough in company. We watch it though as it will rain an army of seedlings which, from their lofty position, can travel some distance. If they find a shadowy area where the competition is less the hogweed will soon be king.
We have watched their evolution in the top meadows, enjoying their creamy flower, but noting their propensity for dominance where they find a niche. Being biennial, or more usually a short-lived perennial, the simplest control in those areas where they risk becoming dominant is to deadhead the umbels after they have done what they can for the pollinators, but before they run to seed. This is a task that is left until the meadows are already toppled by rain so that you cannot see your tracks and always with gloves as the sap can be an irritant in sunshine.
My love of the hogweeds started as a teenager in our garden that teetered on the brink of being taken back by nature. I realise now that it was that line, the meeting place between the areas we gardened and those where we tried to keep the upper hand, that defined and continues to underpin my interest in gardening. The hinterland of order and apparent disorder, of horticulture and ecology.
I began the conversation between these two worlds by planting giant hogweed into the orchard at the back of my long border with a number of rambunctious perennials that could cope with the competition after the first flush of bluebells. I was reading William Robinson at the time and the über-nature he was emulating with his wild plantings was rapidly manifested in the bolt for the sky as the Heracleum mantegazzianum reared from the ground in its second year.
I have no recollection of where I got the seed, but very soon and within the two years of completing its life cycle, I realised my mistake. The first summer of flower I asked my mother and father to pose under the giant for a photograph to mark the moment, only for Dad to succumb to nasty burns from its sap. We didn’t know until it was too late, but chemicals in the sap can cause photodermatitis, where the skin becomes very sensitive to sunlight and may suffer blistering. Dad got off lightly, but my second mistake was to let it seed and the subsequent rash of seedlings took us another couple of years to eradicate. The distinctively toxic smell of the sap is forever etched in my memory.
The giant hogweeds – for there are several species – were introduced into Britain and Europe from the Caucasus Mountains in the nineteenth century. They were first recorded as Heracleum giganteum in the Royal Botanic Gardens Kew Seed List of 1817, the seed having been supplied by the Gorenki Botanic Gardens in Russia. They became popular in the trade, the Victorians taking to their drama and architectural presence, but it wasn’t long before they escaped into the wild, their boat-like seeds floating down rivers and their dominant presence treading, as giants do, without consideration for their footfall.
I have never planted another Heracleum mantegazzianum. It is on the EU list of invasive alien species and here in the UK it is an offence to introduce this species into the wild. Burned as I was by the experience, but not so critically that I lost my fascination, I have begun to experiment with a number of other species in the garden here. They are planted behind the open barn, running alongside a mown track and where I can control the outcome. Heracleum stevenii is flowering here for the first time this year. Short at about waist height here, but with handsome umbels of well over a foot across, they strike an impressive horizontal. You will find little about this plant if you look it up online, but Nick Macer of Pan Global Plants has found it to have a similar life cycle to the giant fennels. Some plants return for a second year after flowering whilst others die after seeding. It grows taller, to chest height, in his walled garden. His seed came from the wild collections from the Crimea of Bob Brown of Cotswold Garden Flowers.
In the long grass down by the ditch I have introduced Heracleum lehmannianum (main image). Nick collected this perennial hogweed in Tajikistan in Central Asia. Though I am wary with all heracleum and do not handle them without gloves, this giant has never burned anyone in his nursery where you see it towering at three metres by the sales cabin. It is also not a prolific seeder in this setting but, once bitten, twice shy, I am going to deadhead my plants, as I will our native hogweed, to prevent it from seeding and becoming an unwelcome presence. For now, it is anything but. I am fifteen again and as awestruck as ever.
Words: Dan Pearson | Photographs: Huw Morgan
Published 11 June 2022