You know you’re getting old when your teenage children go out on a Saturday night and you stay in - but you don’t mind because you’ve got a garden visit to look forward to on Sunday and you want to be up early to pack the pork pies, hard boil the eggs and fill the Thermos.

Yes, I’ve reached that stage of life when the sensible sandals come out, the picnic rug goes in the boot and I start collecting clippings from the Sunday colour supplements about where to see the most spectacular arboretum or neatest herbaceous border.

It started a couple of years ago when I wanted to catch up with an old school friend from Watford Grammar and she suggested meeting in the gardens of Serge Hill in Bedmond, where the award-winning Tom Stuart-Smith has designed his own contemporary garden alongside the very traditional one at his parents’ Queen Anne house next door.

Both gardens were open as part of the National Gardens Scheme, which raises money for healthcare charities by asking people to open their gardens to the public for one day each summer.

To my surprise, I was absolutely dazzled by the gardens and also interested to learn the scheme began in 1927 when a member of the (then) voluntary district nursing organisation came up with the idea of raising money by capitalising on the nation’s obsession with gardening.
Garden owners could charge visitors "a shilling a head", which would help fund training for nurses.

Since then, I’ve dragged my friends, husband and children around all sorts of private gardens, with the bonus (for a nosy parker like me) that I get to gawp at the often fabulous houses too. Envious, moi?

On Sunday, for instance, we visited nine gardens in the tiny and preposterously pretty village of Dinton between Thame and Aylesbury, which is well worth the hour’s drive from Watford.

The village is so jaw-droppingly gorgeous it has been used several times by the makers of Midsomer Murders, which must surely be dead good (ha!) for business.

Even my daughters were impressed, which is really saying something.

Of course my kids think my new-found love of gardens means I’m just days away from insanity, bunion removal operations and tying my handbag to my Zimmer frame, but I see it as a late flowering interest in how the other half spends their Sunday afternoons.

Certainly, no one could call me green-fingered.

Far from it; in fact during the flat-sharing days of my 20s and 30s, I was the one who managed to kill the cacti in the sitting-room by watering them and suffocate the more cool-blooded plants by putting them on the shelf above the gas cooker.

Yet it should be in my genes to be good with plants.

My paternal grandparents made a decent living growing flowers commercially and to this day, I remember playing hide and seek between the regimented canes of sweet peas and runner beans in their garden as being one of the highlights of our holidays there.

Somehow, in the unforgiving climate of Northern Ireland, they grew rows and rows of prize-winning dahlias and spiraea, flowers which still have the power to make me gasp in wonder whenever I see them.

I also loved racing through the magnificent terraced Italian gardens that led down to the beach at Scarborough, where my maternal grandparents lived, and thinking if the Italians could garden like this and still find time to run Scarborough’s celebrated ice-cream parlours, theirs really was the dolce vita.

I also remember my Yorkshire grandmother telling me the same joke every summer about Pansy blushing when found in the same bed as Sweet William and wondering why on earth the grown-ups found this so funny.

Who knew that horticulture could be so subversive, even in those politically incorrect days? 

I’d like to think my mid-life interest in gardens is evidence of a hankering to return to the innocence of childhood, when life was simpler and your dad got home in time to water the roses and you got to help your mum pick raspberries for tea.

When rockeries were still fashionable, decking was something you found on ships and garden gnomes were naff but loveable, not some post-modern ironic style statement.

It could be nostalgia, it could be I want my children to appreciate colour, perfume and texture in gardens, just as my grandparents tried to teach me.

It could be that I will do anything to drag them away from their screens on a Sunday afternoon, even if I do have to fork out for cake in the village hall afterwards.

Whatever my motive, my reward comes in seeing my children’s cynical adolescent faces light up in amazement when they walk into a lovingly tended garden and see what a combination of hard work and imagination (with a little help from nature) can achieve.