Bad Blackthorn

It’s going to be a glorious Blackthorn blossom year. Its spectacular sprays set off against dark wood are a welcome harbinger of Spring. It’s a species which does well in the hedges around us, and the apocalyptic weather has meant many of them have been uncut or only partly flailed this year. Good news for bees and also Hairstreak butterflies, whose larvae are killed in industrial numbers by flailing.

Good Blackthorn

Blackthorn is a lovely plant, good for biodiversity generally. As a native shrub/tree it’s only beaten into flower by the near as dammit native and close relation Prunus cerasifera, the Cherry plum, and plays an increasingly important role in providing pollinators early season nectar. Sloes are an autumn boon too, of course.

It’s a brilliant hedge plant, making an impenetrable spiny barrier. Much slower growing than hawthorn, it lays as well and suckers vigorously – helpful to thicken a hedge. Although it’s a tough old plant, Blackthorn only has a shallow root system, associated with this vigorous suckering tendency. Don’t plant it next to a lawn! This feature makes it vulnerable to periods of drought, I reckon, so it’s going to struggle over the next few years.

It seemed a bit harsh to hear it described on last week’s Gardener’s Question Time as “evil”. I might reserve evil for a small group of invasive non-native species like water fern, Azolla. Blackthorn? Not so much.

GQT’s Bunny Guinness doesn’t like the suckering (fair enough, but it can be a virtue) and worries that we’re going to get sepsis from it. This is a funny one. Blackthorn has longer spines than Hawthorn. They’re brittle and will break off. Like any plant, they will be covered in microbes, but the way they get embedded under the skin makes their wounds more likely to become infected. As a hedgelayer I know this only too well! The spines need removing and the puncture well cleaned. Horse owners are wary of Blackthorn wounds too; the thorns can penetrate some way. The bark contains prussic acid, but it’s not clear whether this is a factor too, so far as I can make out.

How many people get sepsis from Blackthorn? Who on earth knows? A fair number of Blackthorn wounds from the millions of Blackthorn plants around the country get infected, I’m sure. A few must lead to more serious complications. The interweb is full of largely apocryphal stories about sepsis and visits to A&E. Blackthorn sounds terrifying. We should all stay well away from it. Who on earth in their right mind would actually want to plant it?

This tells us something about our current relationship with the nature around us. Back in the day hedge work was all done manually and protection was more rudimentary. Blackthorn wounds must have been much more common and treatment of infections much less effective. Perhaps this contributed to its association with witches and dark magic. Who knows - and many plants have this kind of folklore associated with them. 

If you’re reading this and you have had a significant issue, I’m very sympathetic and it’s very bad luck. The lack of any analysis of the numbers of people who suffer like this suggests they are vanishingly small. I’ve had plenty of very minor infections from Blackthorn, but they’ve cleared up with careful cleaning. I would feel very hard done by if they had caused real problems, even though I’m one of a very tiny % of the population who work with it regularly.

Stories like this tend to get traction, for some reason. A few years ago everyone got very over-excited about Corncockle. This now rare plant does indeed have toxic seeds. Is there any record of anyone dying from eating them? No.  Eat some and you would be sick. As a result of the story, they were excluded from seed packets and specified seed mixes. What a pity; Corncockle was widely sown beforehand, which had been helping numbers recover.

Danger Danger... not so much

There’s danger lurking everywhere in your garden. Many plants are poisonous, not just the well-known ones like Foxglove, Monkshood and Yew. Daffodils can see you off if you eat them. The RHS website warns gardeners about sepsis, tetanus, Legionella, Weil’s disease and Bioaerosols (a new one for me). I don’t want to dismiss these risks as non-existent and it’s helpful to be aware of them of course, but let’s keep a sense of proportion. Nature in the U.K. is largely benign. Would I plant a Blackthorn hedge next to a children's playground? No. Would I include it in a field hedge mix? Absolutely, yes.