STANDING in the middle of the fernery at the Museum Gardens is what looks for all the world like an exotic tropical tree – something from the upper reaches of the Amazon, perhaps.

It’s nothing of the sort. This is just a humble yew tree – one that has been turned on its head and planted with its roots in the air.

It seemed like a good idea, says head gardener Sjaak Kastelijn. He and his team took the tree down because it was blocking the light.

“We wanted to develop that border, and it has opened it up a lot more. But instead of throwing the tree away, we thought we would put it back in place in the garden. It is great for wildlife. We’ve had wrens nesting in it!”

It is an example of Sjaak’s quirky approach to garden design that, over the last two and a half years, has seen a slow transformation taking place at Museum Gardens.

The fernery is just a part of it. Tucked away in a cool, shady corner at the side of the Yorkshire Museum, it is a celebration of this most ancient of plants. Because of the museum’s collection of fossils, ferns – which have been around for hundreds of millions of years – are obvious plants to have in the gardens, says Sjaak (his name is pronounced ‘Jack’, in case you are wondering).

“They are fantastic plants, and the thing is, if you find a fossil, nine out of ten times it will have a print of a fern on it.”

So this fernery is a way of connecting what is outside, in the gardens, with what is inside in the museum. Sjaak has underlined that by including some chunks of ancient Yorkshire limestone with fossil plants embedded in them. These, plus the upended yew, make for a fernery with a difference.

Sjaak, who is very Dutch – he grew up on a dairy farm near Utrecht – makes no apologies for this. “A garden is a form of art,” he says.

That’s certainly a philosophy he is putting into practice at Museum Gardens. There’s that up-ended yew, for a start.

Wood from a pear tree which blew down will be used to make seating (a wonderful example of recycling), and regular visitors can’t fail to have noticed the way Sjaak and his team have used stone from St Mary’s Abbey (not to mention Roman stone coffins, some of them from St Leonard’s Hospital) as features in the gardens, setting off the plants and beds but also forging a connection with the museum’s Roman and medieval architecture. He has also cleared out the undercroft of St Leonard’s Hospital, so for the first time in ages you can get a view right through it. There are plans to introduce seven information panels in the undercroft, turning it into a feature itself.

Art and design is only a part of what he is bringing to the gardens, however. He also wants there to be a clearer focus on the botany, too.

When they were first developed by Sir John Murray Naysmith in the early 1800s, the Museum Gardens were designed as botanical gardens to showcase exotic species brought back by travellers from around the world.

These were intended to complement the collection of fossils and other geological specimens in the museum itself.

Over the years that side of the gardens got lost sight of.

They are hugely popular with picnickers and people on their lunch break – something like 1.3 million visitors pass through here every year, Sjaak says – and provide a stunning setting for the museum and the ruins of St Mary’s Abbey. But how many visitors can really identify many of the exotic plant and tree species?

Sjaak hopes to change all that. As part of an ongoing five-year plan, he and his team aim to return the Museum Gardens to something more like what the founders intended.

He won’t be slavishly trying to copy the gardens of the 1800s – but he will be trying to focus more attention on the amazing plants here. He and his team are already making a great start, with beds such as the one he calls the Prairie Border: a large central bed near the entrance to the gardens.

Beneath the trees that shade the bed is a wealth of low, ground-hugging plants – some fern-like in appearance, some grasslike, others colourful or spiky.

What makes this bed special however, is that every one of the plants here – apart from a few tulips to add colour – is a native of the American prairie. The bed harks back to that glorious age of exploration when Britannia ruled the waves and British explorers were bringing back the exotic species they had discovered on their journeys to grow at home.

Among the plants here are asters, echinacea and tradescantia, named after the naturalist John Tradescant who travelled all over the world in the 1600s collecting plants and seeds.

The Prairie Border is a classic example of Sjaak’s aim of making the gardens beautiful, as well informative. “There are different layers to it,” he says. “It looks nice, but at the next layer, it is about the prairie itself. Only about one or two pert cent of the original prairie is left.”

Everywhere you go, Sjaak is starting to do that. He plans to expand the rockery near the Marygate entrance to the gardens, and aims to ensure it pays tribute to York’s famous Backhouse nursery which, during Victorian times, was known for its rock gardens. There are also plans to create an Observatory Border just below the observatory itself, with plants named after the stars or in the colours of the planets, or in patterns of black and white to represent night and day.

There will also be a mini-waterfall opposite the fernery, and it may also be possible at some stage in the future to build a new glass house for hothouse plants – though that is unlikely to be within the next few years.

As well as introducing exotic new species, Sjaak and his team will also be introducing better signing and labelling, to help visitors understand more about the gardens. Ultimately, his aim is to have all the plant species in the gardens identified, each with a little plaque saying what it is, plus more general interpretive panels explaining the general theme of different beds.

He never wants to lose sight of the fact that these gardens are here for people to use, he says. But they are about much more than just grass and trees. “I also want this to be somewhere where people can learn something, can be amazed by the beauty of nature!”

HE may hail from the other side of the English Channel, but Sjaak Kastelijn has made no secret of his love for his adopted city of York.

He and his wife Cecile even went so far as to name their son – conceived during a brief visit in 2006 – after the city. Shades of Brooklyn Beckham – though York Kastelijn has a much classier ring to it.

Sjaak and his wife had been regular visitors to the UK. “We had been coming for about ten years on our holidays,” said Sjaak, 39. “We’d been to Scotland, Wales, Cornwall, Devon, everywhere except Yorkshire.”

And then they spent a night at the Pinfold Cottage Bed & Breakfast during a four-week tour of England – and decided the city was the “most beautiful place on earth”.

“We went back home from this holiday, and thought ‘we could live here’,” Sjaak says. “York is a fantastic place, full of heritage, but a light and open city.” Add in the beauty of the Yorkshire Dales, Moors and coast, and it makes it hard to beat, he admits.

Brought up on a dairy farm near Utrecht, he originally wanted to be a journalist. When that didn’t work out – “I was more interested in going to parties!” – he found himself working for a landscape gardener at Sittard, near Maastricht. He did a four-xyear degree in horticulture, then got a job at Mondo Verde, a themed garden park with glasshouses, and Japanese, Chinese and English gardens.

He rose to be head gardener, but after he’d been there for several years, the park was taken over by new owners, who wanted to turn it in a Dutch version of Flamingo Land. Sjaak and Cecile decided it was time to move on.

They’d always loved Britain. “It’s the space, the natural environment,” Sjaak says. “We loved Scotland for walks, and we loved the British people – they are very, very friendly – and the way people are so involved with the heritage here.”

He began looking around for a gardening job here – and when, after that brief visit to York in 2007, he learned that there was a job going at Museum Gardens, he jumped at it.

The family now live in Crayke. In addition to his gardening duties in York, Sjaak and his wife also run The Dutch House at Crayke – a combination of ecological sculpture garden, tea room and arts studio.


Museum Gardens – a history

The ten-acre Museum Gardens were first planted in the 1830s, at about the time the Yorkshire Philosophical Society opened the purpose-built Yorkshire Museum.

Landscape architect Sir John Murray Naysmith was appointed to draw up a design, and the gardens were laid out to show off the various buildings – such as the museum itself and the ruins at St Mary’s Abbey – within the boundaries, and to house plant specimens from around the world. At one point, there was a glasshouse for tropical plants such as sugar cane, coffee, tea, ginger, cotton and rare orchids, and a pond containing a rare water lily, the Victoria Amazonica.

• There are guided walks of the Museum gardens, led by experienced garden guides, every Sunday from noon to 1pm for those who want to find out about the botanical specimens and rich archaeology.