For research purposes and the seed of the nation, Kathy is also testing 40 varieties of potato, and a collection of other fruit and vegetables. She has even introduced Scottish Dumpies, a rare breed of short-legged hens with an acute sense of hearing, which once, allegedly, served as look-outs for Bonnie Prince Charlie. When the visitors have retreated, the Dumpies are allowed to roam the garden in search of slugs.
Kellie, near St Andrews, has no flamboyant Italian-style design or planting, rather it is a gem of practical gardening: a mix of flower borders, lawns and shrubs, extensive fruit and vegetable plots, surrounded by impressive walls. It is a vision of how you would like your own patch to be - crammed borders and riotous colour, with the odd surprise.
The garden first served up produce to the Oliphant family in the 16th century, when the outline of the current walls was laid, along with the paths and borders. The structure has largely survived the test of time, even through long periods of disrepair in the 19th century and ownership of several families, including the Earl of Mar and Kellie.
It might have crumbled completely into ruin, were it not for Sir Robert Lorimer, the renowned Edinburgh architect and garden designer. In 1876, the Earl of Mar and Kellie accepted a leasing agreement - which was to last 60 years - and allowed the Lorimer family to restore house and garden in characteristic artistic fashion. Robert's brother, John, the eminent Scottish painter, lived at Kellie and contributed to the project, while sister Louise wrote up the garden's delights.
Victorian touches crept in, principally through the blue walkway, a summer border of sweeping blue catmint and towering delphiniums, the summer house and two corner gardens. The lawns were laid only in 1955 by sculptor Hugh Lorimer and his wife, Mary, the last in the family chain before the transfer to the National Trust in 1970.
Kathy took over seven years ago and has quietly hauled up four lawns, restoring vegetable plots and borders and banning all chemicals. Roses were a traditional feature of the garden: "Nuits de Young" and "Roger Lambelin" have recently been introduced from specialist growers. The policy is only to use plants which were available in the last century and to conserve rarities.
She revels in researching and preserving the nation's crop heritage, pointing out that the Victorians would have a pea catalogue with 60 varieties - "now you get eight". Veg and fruit are her passions, along with her organic approach, which also encourages bird life in the garden - 67 species have been spotted.
Even as a girl in Lancashire, she drew pictures of gardens and was fascinated by plants. But it took a few devious routes to reach Kellie. She trained in Liverpool as an environmentaloutdoor education teacher, but it was not for her. "Nobody told you what to do when a 14-year-old told you to eff off," she says. Undaunted, her interests drew her into residential work with disturbed young people in Cheshire, Manchester and Cumbria before she concluded that too was not for her.
"I'd had enough after eight years," she says. "Self-preservation had to come into it. In this job, you can end up physically exhausted, but in that job I was emotionally exhausted." She turned to a one-year course in horticulture at Isle College, Wisbech in Cambridgeshire, and from there to a career as a jobbing gardener in Cumbria.
Ten years ago, she married and came north to Fife where she worked as a seasonal gardener at Kellie. Three years later, she was appointed head gardener and in winter, the only gardener. Her current seasonal assistant, Duncan, who maintains the magnificent castle lawns, was once a groundsman at Wembley.
Despite its formal layout, Kellie enjoys an almost free-range planting scheme. Kathy likes plants which self-seed and the informality and tranquillity of the garden are among its chief appeals. "I like to see people falling asleep on benches and children making daisy chains on the lawns," she says. "You won't be rich being a gardener, but it's an idyllic job."
Kellie Castle gardens are open throughout the year from 9.30am to sunset. The castle is on the B9171, three miles north of Pittenwee