Gardening: Just an overgrown thug that no one loves: Deep in the urban jungle Magnus Mills gives refuge to an odd specimen

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MY MATE Tommo didn't like the look of it. 'Why do you want to grow a giant weed?' he asked suspiciously. We were standing in my back yard in Brixton one day last year and he was regarding the Thing with deep distrust as it reared menacingly over us. I even noticed he was standing back a bit, as though it might bite him.

'It's not a weed,' I lied, 'It's a wild plant called giant hogweed. Very interesting foliage. It's an umbellifer: it flowers in umbels. You know, like parsley.'

'Funny-looking parsley,' he said.

I then realised that Tommo was not impressed by my prize specimen. My wife doesn't like the Thing either, even though it has lived with us for almost three years. She says it has got to go.

Well, I think a plant that can grow several yards high in one year is impressive, so it stays. The giant hogweed (or Heracleum mantegazzianum) has thick hollow stems supporting massive lobed leaves, and it also has a tendency to loom. It just grows and grows.

I have some other big green monsters out the back as well, such as Gunnera manicata and Rheum palmatum. But they have a much more sedate rate of growth, whereas the Thing seems to be a bit of an outlaw, which is why I keep it separate from the rest.

It lives in a four-gallon oil drum. It doesn't seem to mind being confined to quarters, as long as I feed it now and then. But it does behave oddly, all the same. The plant is supposed to be monocarpic, which means that it dies after flowering. My specimen flowered last summer sure enough; the flowers were like great skeletal parasols, dropping seeds everywhere. And then it died back as expected and I thought it had gone for good.

But it was only playing dead, and this spring it came back again, bursting out of its den like a hibernating grizzly who'd just woken up. I gave it a handful of 6X and proudly watched it nudge its way skyward again.

But I am afraid the giant hogweed has few other friends. The Ministry of Agriculture, Fisheries and Food definitely doesn't like it. Indeed, if I was attempting to 'plant or otherwise cause to grow' the species 'in the wild' I could be prosecuted under the Wildlife and Countryside Act 1981.

The ministry sees the plant as an environmental hazard, an interloper that forces other plants out and causes soil erosion. And it contains a sap that can have a nasty effect on its (human) victims.

The giant hogweed has close relatives such as cow parsley (Anthriscus sylvestris) and cow parsnip (Heracleum sphondylium). But these are harmless country cousins by comparison. The ministry describes them picturesquely as 'wayside plants', whereas the giant hogweed is just a thug, chucking its seeds around by the thousand.

Apparently these seeds are good travellers, especially if there is a waterway for them to flow along, colonising the banks as they go.

Just to be different, the seed responsible for my plant came here on the bus, smuggled out of Kew Gardens three years ago. They had a giant hogweed held in captivity, presumably for scientific purposes. It stood in the herbaceous borders, magnificently dwarfing the other umbelliferous plants on display. There were seeds lying all over the place so I picked one up, took it home and planted it.

Charles Shine, who runs the herbaceous department at Kew, seemed shocked when I told him recently I was growing a giant hogweed at home. He cautioned me solemnly: 'Did you know that it is an offence under the Wildlife and Countryside Act 1981 to plant or otherwise cause to grow . . .' etc, etc.

I thanked him for his advice. 'It's OK,' I assured him, 'the Thing is under control.'

But then I looked out of the window and thought again: 'Or is it?'

The leaflet Giant Hogweed: the Problem and its Control (ref: CL45) is available from the Ministry of Agriculture, Fisheries and Food, Whitehall Place, London SW1.

(Photograph omitted)