Gardens: Inveraray Castle Gardens are being

"Iona gave me a pair of clippers and asked me to go out into the garden and cut back a plant," Eleanor says. "I grew up in South Kensington and found this really difficult." Nervously she trimmed just one centimetre off the offending shrub and quietly hung up her secateurs.

Ten years later, Eleanor is now mother to Archie, seven, Rory, five, and two-and-a-half-year-old Charlotte, and the situation is very different.

While refurbishing the family's private apartment within the castle and persuading her husband, Torquhil 13th Duke and Chief of the Clan Campbell, to install a woodchip boiler that feeds 112 radiators took precedence, she recently began to think seriously about the garden.

Seduced by the glorious yellows, oranges and reds of the rhododendrons and azaleas, the blossom of the prunus and their fiery autumn foliage, Eleanor found herself increasingly drawn to the plants she could see from within the castle.

"The garden rapidly became more and more of a priority," she says.

Both she and her husband relished the challenge of building on the existing scheme while breathing new life into areas that had become overgrown and neglected.

"I'm learning fast," Eleanor enthuses. "I've got to learn. Torquhil is no good in the garden, he's much better with a chainsaw on the river bank."

With the skilled help of head gardener Jamie McCarthy, and his team now in place, work is ongoing to rejuvenate the planting while retaining the character of the design. The formal garden opened to the public for the first time last year.

Set within a magnificent, 18th-century designed landscape punctuated by mature trees with steep hills rising in the background, the castle grounds are a short distance from Loch Fyne. Built of blue-green stone, the castle, like the landscape, owes much to the efforts of the 3rd Duke, who demolished and re-sited the entire village of Inveraray to accommodate his project.

Although the gardens were originally planned as early as 1600 when the Lime, Town and Glen Shira, also know as the Grand Approach, avenues were laid out, the 3rd Duke later added the Watch Tower known as Dun na Cuaiche, The Doocot and Frew's Bridge. He also rerouted the River Aray to form canals and cascades.

Eleanor explains: "Walter Paterson, from the 2nd Duke's staff at Caroline Park near Edinburgh, was recruited to be his gardener. Paterson was said to be a skilled plantsman and landscape gardener and was partly responsible for the cascades and lawn formation."

A century later the two-acre formal garden was laid out with two circular and two Saltire flowerbeds divided by a gravel path edged with a band of grass.

Subdivided by horizontal paths, the remaining rectangles, known as the Flag Borders, are further sliced into triangles with a broad perimeter path.

Using the background structure of spring plants with autumn foliage, such as azaleas, rhododendrons and pieris, a plan was established to extend the season by adding a collection of summer plants, the names of which Eleanor has enjoyed learning.

"Jamie and his team of two gardeners – there used to be 14 – are propagating plants such as varieties of purple-leaved heuchera, lupins and hostas."

Jamie is keen to "add as much structure and jazz," to the scheme as possible including surprising architectural plants, such as fennel and artichoke. On a romantic note he is growing some of his favourite blue nigella, purple verbascum, in addition to eryngium, sweetpeas and clouds of verbena bonariensis, a magnet for bees and insects.

This year work started on developing the border at the foot of the garden where the structure of elegant stone statues creates a striking focal point.

Here among the foliage of established dwarf rhododendrons, such as Blue Diamond and Blue Tit, he has planted 60 teasel, dipsacus fullonum, a bi-annual with spiky leaves to contrast with the soft, low-growing foliage of stachys lantana.

An injection of colour comes from orange and red day lilies. Adding these herbaceous plants, Jamie says, has created a strong note of interest into an area where "there was not much colour after the rhododendrons finished flowering."

Torquhil recently instigated a programme of daffodil planting: last year 5,500 daffodils were planted and this autumn a further 10,000 bulbs will ensure a remarkable display in the spring.

Work has already begun on transforming the area close to the arched bridge, the site of the old village with its spectacular loch views, into a wildflower meadow.

Known as the Main Lawn, this area has sprung into life, as Jamie explains: "We had no idea how many wild flowers there were down there until the grass was left to grow. We have planted a mix of additional wild flowers such as daisies and vetch and 200 mecanopsis." The latter, he says, "seed like nobody's business."

The plan is to cut the meadow just once a year in September, raking up the debris in October.

Despite these exciting plans, Eleanor is realistic about how long it will take to fully understand the garden.

"It takes time," she says, "but we have the advantage of being young and we have got a lot of time to learn. We must concentrate on what we can do with limited resources."

Essentially this remains very much a family garden. "Lots of hide and seek goes on among the shrubs and we have Easter egg hunts to which local and visiting children are welcome.

I've got no plans to do a garden like Alnwick; I need to get my head around this. Aren't we lucky to have this wonderful place?"

With an energetic duchess unafraid of rolling up her sleeves and doing much of the work herself, "it takes a day to wash a chandelier," she says, it is certain that these gardens surrounding one of Scotland's most visited castles will be given the care and attention they need to bring them into the 21st century and beyond.

Inveraray Castle Gardens are open until 31 October, admission 4, www.inveraray-castle.com

This article was first published in The Scotsman, 23 July, 2011