Urban Gardener: Yellow fever

It's raining, and I'm perched rather precariously on a wobbly ladder against some scaffolding overlooking a tiny garden in Hither Green in south-east London. Below me, waiting to have their picture taken, my partner's grandchildren Florence, age seven, and Otto, age six, are being extremely patient.

"OK, not too much smirking. Good. Now can you stand in that clearing?"

"That's our den!" says Floss, a little indignant that the hallowed space should just be referred to as a clearing.

"Sorry, your den. And it's OK to smile now."

Otto, whose front teeth have just fallen out, tries to keep tight-lipped but another wobble throws him into hysterics.

"Why do you want to put our garden in the paper?" says Floss.

"Because it looks good and it's a great example of how nature can look after itself."

Florence and Otto are no strangers to gardening or our allotment and, with a backyard that would put a smile on the face of Van Gogh, they are as curious as I am to know why my own efforts at growing sunflowers are so hit-and-miss. Every year we try but it takes an inordinate amount of effort to keep slugs and snails from demolishing the seedlings before they can toughen up to look after themselves. While sunflowers hate the constraint of containers and never reach anything like the size they would if they start their life in open ground, potted specimens planted out during a sustained period of dry weather (when slugs are less active) are our only hope.

Curiously, Florence and Otto have the same "no-kill" policy where slugs and snails are concerned (and there is no shortage of them in their garden), yet for the third year running sunflowers have flourished against all odds. Their plantation came from three plants we gave them, the seed-heads of which were left to feed the birds through winter. But because of Fatty (a tabby who more than lives up to his name and probably couldn't catch a bird if he tried) they never came and the seed dispersed naturally throughout their 4m x 6m garden when the plants collapsed. The following spring, when Florence and Otto's parents were about to give the garden a makeover, a sea of sunflower seedlings was a good enough reason to procrastinate. I didn't rate their chances but the sheer volume of seeds that had spent the whole winter getting ready for their big push managed to defeat the snails and the garden was transformed into something much more magical than a patio and raised beds could ever hope to be.

Winter came, the sunflowers were chopped and again won hearts and minds when the seedlings appeared the following spring. Now, at the end of its third season, and despite the fact that the flowers have reverted to their wild variety with smaller heads, it looks like I'm out of a job where design is concerned, a relief if I'm honest, as I doubt I could do anything that could make such an impression. Admittedly there isn't the "all-year round interest", but I think people generally get a bit too obsessed with this and the contrast between the brown sticks of winter to a jungle of sun is actually more impressive and something that Florence and Otto will remember for the rest of their lives.

The garden also reminded me of a recent visit to a two-acre site where a prospective client was about to embark on building a new house and garden. The land that had been left vacant for two or three years was a fascinating example of how nature can work when left to its own devices. Seedlings of birch, sweet chestnut and oak had already staked their claim and would soon become natural, not ordered, woodland without any help from humans. It may sound like I'm talking myself out of work but some of the best designers and plantsmen take their inspiration from nature and most gardeners that move to a new home will usually like to wait for each season to pass before making drastic changes. It's simply a game of Follow my Leader.