Looking back, I am not sure how this started. But sometime in the spring of 2005, we found milkweed growing in our front garden. Our next-door neighbour, Clare, who runs a neighbourhood flower shop, persuaded us not to pull it out.

Since then, the two adjoining gardens have had bumper crops of milkweed. We grow other flowers around the milkweed — such as Norm’s deep purple dahlias and scarlet cannas — to make it clear we know the difference between weeds and flowers. And Clare is always reassuring, telling us she has customers who come into her store and pay real money for milkweed. But I haven’t seen a lot of other neighbourhood gardens with our stunning display of milkweed.

So, what would cause otherwise sane gardeners to add milkweed to the mix? Monarch butterflies.

I have learned from Clare that the larvae of these bright orange butterflies with their dramatic black edging feed exclusively on milkweed. And like so many things these days, milkweed has fallen victim to habitat destruction. I guess there are fewer and fewer grassy fields to support the growth and spread of milkweed. So, Clare and I have had to do our part.

What is also amazing about milkweed, Clare tells me, is that the leaves and stems of milkweed are toxic to vertebrate herbivores. When Monarch larvae eat milkweed leaves, they, too, become toxic, as do the butterflies they metamorphose into. This tends to keep predators at bay, as eating the larvae or butterflies makes the predators sick.

I figure our two households have contributed considerably to the growth of Toronto’s Monarch butterfly population. In fact, we have a personal stake in their well-being. So, one day last week, I coerced my photographer husband into coming to the beach with me when I walked the dogs so he could take photos of the Monarchs. The goldenrod was blooming and the orange of the adult Monarchs up against the flowers was striking.

He no doubt thought he had done his part.

But when I went to the beach this past Sunday morning, it was beyond striking. It was amazing. There were thousands of Monarch butterflies, turning the sumac, poplars and goldenrod a vibrant orange in the early morning light. As dog walkers passed by or the dogs got too nosy, the Monarchs would flutter up — an orange cloud.

I am not sure why it happened. It was a particularly windy day. Perhaps, they were holding up, waiting for the wind to die before they attempted crossing Lake Ontario on the way to their winter home in Mexico. (West of the Rockies, the Monarchs winter in California.)

During the summer, Monarchs have a life span of two to five weeks and reproduce several times. But the final generation — those born in late summer or early fall — live eight to nine months. Long enough to make the trip to Mexico and back again in the spring, when the cycle begins again.

Whatever the reason, I got on my cellphone and once again summoned Norm — and our daughter, Kate — to come to the beach. It was worth the trip.

Our garden has generated some interest from readers — or, rather, Norm’s and Kate’s adventure with Roll ’N’ Grow has. Despite the promises of the TV ads, they met with only modest success. The roll that they put into the window boxes actually bloomed. Maybe the window boxes just held the water better, but there we have a bevy of little flowers — Western wildflowers, the package says. We don’t talk about the rest of the Roll ’N’ Grow experiment.

TESSA WILMOTT, EDITOR-IN-CHIEF