OUR new flowerbed looks lovely - 'hot' colours, all reds and yellows, to cheer your way up the garden path. My husband dug and planted it back in the spring, and haven't we been glad of it to cheer the dreary, wet days of this abominable summer?

In among the snapdragons and crocosmia, anthemis, hollyhocks and lupins, he scattered sunflower seeds from an old packet he found on a top shelf. We didn't have any great hopes for them and, to be honest, forgot about them. Until weeks later, walking past the bed, we spotted two new vigorous-looking plants. The sunflowers at last.

Or were they? The leaves didn't look quite right somehow, but they were very young plants. Time would tell.

They went on growing and flourishing, stems growing ever thicker and more grainy, serrated leaves like fingers on a hand. They really didn't look anything like any sunflower we'd seen.

In fact, as they grew something began to niggle uneasily in my mind. Hadn't I seen something like these somewhere before? Not in the flesh, as it were, certainly not in any garden I'm familiar with, but on television, accompanying a news item, just a few weeks before. The police had raided a couple of farms and found barns full of plants raised under heat-lamps. But surely not - they couldn't be? In our garden?

We let the things keep on growing, hoping they'd produce some innocent and pretty flower. They just went on looking more and more like those newsworthy plants. I looked them up in an illustrated guide to herbs and medicinal plants and they still looked too much like those things they couldn't possibly be. A bit broader in the leaf, perhaps, but still very like them. My mother's good on plants, but not that sort. But we do know a couple of people with misspent youths.

We took a photo and emailed it to them. "We don't know where they came from or what they are," I wrote, not entirely truthfully. "Any ideas?"

You could almost see the grins on their faces as they replied.

"My lawyer has advised me to make no comment at this time," said one. "Gosh," said the other. "I'm sure I've seen those leaves on a T-shirt somewhere. Have you tried smoking it or baking it into a chocolate brownie?"

The very idea! I may have lived through the Sixties, but my student days were during the early years, long before the Summer of Love.

"It's probably cannabis ruderalis," our informant went on. "Which is the one that tolerates a temperate climate but doesn't get you particularly high. It'll probably grow another foot or so and then bud, at which point I suppose you could harvest it and make a fairly useless spliff."

Useless or not, what we wanted to know next was if it was any more legal to grow it than the other sort. Our informant drew on his alarmingly full knowledge of the subject to answer that too. "It's every bit as illegal to cultivate or harvest it - unless you have a hemp licence."

Does it count as cultivating it if you have no idea how it got into your herbaceous border? We weren't going to wait to find out. My husband had a bonfire the very next day and they've gone.

As to how they got there, it seems it's not a case of someone spiking the seed packets in B&Q. Most likely, said another knowledgable friend, it's grown from bird seed. Most bird food packets contain hemp seeds, and just now and then one of them germinates.

As for the sunflowers, only one sickly plant ever struggled into existence and that was eaten by slugs. It's not been a good summer for sunflowers. But maybe, in years to come, I'll remember it as the summer when I nearly became a Cannabis Gran.