They were created in 1898 by the remarkable Arthur Kilpin Bulley, a man of curiously contrasting parts. He once stood for Parliament as a women's suffrage candidate - but today is chiefly remembered for his role in the development of English gardening. "I always say that Bulley was the greatest patron of 20th-century plant introductions - arguably the greatest there's ever been," declares Peter Cunnington, the garden's long-serving curator. "I would have loved to meet him."
Bulley was born in 1861 in New Brighton, across the Mersey from Liverpool, one of 14 children of a cotton broker. His interest in gardening began to develop at an early age. On leaving school he joined the family firm, and his appetite for uncommon plants was whetted when he went overseas on business. In 1898 he bought 60 acres of land at Ness on the Wirral, between Birkenhead and Chester, to build a house with a large garden and space for a plant nursery. A lifelong socialist and philanthropist, he kept part of the garden open all the time for the free enjoyment of villagers, later adding a bowling green and tennis court.
In 1903 he established Bees Nursery at Ness, selling plants raised from seed sent to him from Europe and Asia. The following year he dispatched George Forrest on the first of several expeditions to remote parts of China, to search for still greater rarities. Forrest was to become a legendary plant hunter and Bulley one of the great patrons of horticultural exploration. Bees moved to larger premises near Chester in 1911, soon becoming a household name through its cheap packets of seeds, sold for decades at Woolworth's. Bulley, meanwhile, continued to improve the garden at Ness. It still contains several plants brought back by Forrest and other explorers (including Francis Kingdon Ward) in the early years of the century.
Bulley died in 1942, and in 1948 his daughter Lois presented the garden to the University of Liverpool, on condition that public access would continue. In the years since, it has become a valuable research centre and an increasingly popular attraction for visitors.
Next weekend a gala festival will celebrate both the gardens' centenary and the 50th anniversary of the university's ownership. There will be stalls selling plants raised at Ness and experts will be on hand to answer horticultural queries. Local craftspeople will display their wares and for children there will be face painting and other attractions.
Although the rhododendrons and azaleas are just past their dramatic peak, there is plenty to enjoy next weekend. Look out for the brilliant blue meconopsis, or Himalayan poppy - one of Bulley's great passions. A series of trails through the gardens, each described on an individual leaflet, guides visitors to items of specific interest.
One, the China Trail, traces plants brought back from the Far East by Forrest and the other plant hunters. Yet, while the core elements of Bulley's gardens have been preserved, there has been continual evolution to keep up with the times.
"I want it to move on," said Cunnington, as he walked me round. "We aren't trying to maintain it as an historic relic. Bulley wouldn't recognise much today." There were three main elements to his original gardens. The first was what he called the specimen lawn, to the north of the house, where he placed some of the prized shrubs and trees that had been discovered for him. To reach it today, visitors first go through the rose garden, approaching its best just now, and on to a broad grassy area edged by rhododendrons and a pine wood - a cool retreat on a warm day.
A few of the later-flowering rhododendrons are still strutting their colourful stuff, supplemented by lilies and penstemons. On the specimen lawn itself, the huge Magnolia thompsoniana should be in flower next weekend, and perhaps the lovely Cornus kousa. Both were planted in Bulley's time, as was the Pieris formosa forrestii, named after George Forrest. This variety is not hardy in most parts of the country but Ness, with water on three sides, enjoys mild winters. On the rare occasions when the Pieris has been felled by frost, it has quickly recovered its vigour.
Nearby are the old nursery packing sheds and stables, surmounted by a bell. It would be rung at five to six every morning to summon estate workers from the village, and again at half past five in the afternoon, when they were allowed to down tools. Bulley's social conscience did not extend to shortening the working day.
The next area is what he called his seasonal garden, a series of rectangular beds that peaked at different times of the year. During the Second World War, the beds became overgrown because nearly all the gardeners were conscripted. When the University took charge the area was grassed over to become a lawn, with a wide herbaceous border running down the eastern side. Just beyond is a heather garden, and nearby a collection of home-bred Ness Holt azaleas. This new strain comes into flower in June and July, later than most, so they should be at their best next weekend.
Looking west from here, tremendous views open up over the River Dee and its surrounding saltmarsh, an important wild bird habitat. A sleek modern suspension bridge carries a road over the marsh, and beyond is Moel Famau, the highest peak of the Clwyd hills.
The third principal element of Bulley's domain was the three-acre rock garden, constructed from local red sandstone and sited in a deep pit created by the extraction of marl - limey clay used by farmers as a fertiliser. During the war this garden too ran out of control, submerged beneath brambles and gorse. In the Fifties it was cleared and planted with low-growing shrubs, for ease of maintenance, but now Cunnington is slowly restoring it to its original purpose, replanting it with Alpines.
Near a small pond are clumps of Primula bulleyana, a candelabra-shaped yellow flower discovered by Forrest in China and named after his patron. Since Bulley's time, a charming new rockery has been built of tufa, a porous stone, and the illusion of a Swiss landscape is enhanced by a picturesque waterfall.
Bulley was obsessed with Alpines and in 1921 was the prime mover in a scheme to create an Alpine garden on the side of mount Snowdon, planted with the distinctive flowers of the European and Asian hills. His enthusiasm got the better of his judgment, and he was attacked by patriots and conservationists for introducing alien plants on to the much-loved mountain, with the risk that they would over-run native species.
The Snowdon garden was eventually abandoned amid acrimony. As far as Cunnington is concerned, it amounts to the sole blemish on Bulley's record as a conscientious plantsman. "Very much out of character," he muses sadly.
On the slope from the rock garden up to the old house, now used as the garden offices, a series of south-facing terraces have been created where the most tender shrubs and perennials can survive - even a banana tree made it through the winter. Climbing up, the honey scent of Euphorbia mellifera mingles with the contrasting aroma of the curry plant (Helichrysum serotinum), whetting your appetite for tea in the billiard room that Bulley built for his son Alfred's 21st birthday.
Since Cunnington joined the staff in 1966, he has seen the public areas double in size and immeasurably increase their appeal. Ness gets about 130,000 visitors a year, but he believes he could double that with better facilities, in particular a large conservatory to draw people in the lean months between autumn and spring. Although still part of the university, the gardens have been hived off as an almost self-supporting unit. They offer courses on propagation, pruning, flowering and garden photography, and a series of Sunday lectures in the winter. Open-air concerts, theatre, plant sales and car-boot sales are held from time to time. The visitor centre is licensed for weddings, with home-grown myrtle available for the bride's bouquet, in the Victorian tradition.
All this may or may not make Bulley turn in his grave. If his ghost were to show up at next weekend's festival, to see family groups licking ice- cream among his precious Alpines, enjoying the clowns, face-painters and morris dancers, what would he think? "I'm sure he would approve," says Cunnington. "He was very broad-minded."
! Ness Botanic Gardens are at Neston, off the A540 between Chester and Birkenhead, tel 0151 353 0123. Open daily except Christmas Day from 9.30am, entrance pounds 4; pounds 5 on Garden Festival days, Sat 6 and Sun 7 JuneReuse content