The till at Triscombe Nurseries is an old fish-box, payment is strictly by cash or cheque only and there are no displays of scented candles or a restaurant – it's a proper nursery, then, not a garden centre, writes Chris Rundle

S tuart and Mary Parkman may have produced a son whose work as a computer expert takes him round the world but at their business, the cash drawer in the till is still the original one made by their predecessor – from an old fish-box.

Neither does the "office" boast such a thing as a card machine – payment is strictly by cash or cheque. Though your eye might well be caught by the heap of potting compost in one corner, the ancient garden tools hanging on hooks as though they have just been put away, and the piles of books and catalogues.

Your attention could well also be drawn to a pot saucer containing bird seed – particularly when a robin or blackbird flies in through the open door, weaves its way between Stuart and Mary and alights on the bench to feed from it.

And although you might think you are in a garden centre of some kind, there is no piped music, no displays of scented candles and other fripperies and no restaurant. After all, says Stuart, look at the state of his hands: he'd be the last person you'd want to serve you a cup of tea.

No, this is a plain, simple and very old-fashioned plant nursery, a flourishing survivor from the time before we even coined the phrase "garden centre", where the object is not to sell you ornamental bird baths or floral wellington boots with your plants, but to send you away with the knowledge of where and how to plant and raise them.

Triscombe Nurseries lies on a south-facing slope of the Quantock Hills and is reached down the narrowest of lanes from the A358 between Taunton and Minehead. And if the term "south-facing" conjures an image of a benign climate then think again: we are 500 feet up here, though sheltered – the 500-foot contour line follows the lower boundary of the Victorian walled garden that has been supplying gardening enthusiasts across the West Country for decades.

They still come, from Barnstaple, from the Dorset coast, from Cheltenham, to stock up here and not merely because Stuart and Mary plant, propagate and graft all their own plants, shrubs and trees, not just for the sound wisdom they give away with each purchase – but because they know they are unlikely to get a failure.

After all, if plants can survive 500 feet up on the Quantocks then they're pretty much guaranteed to do well pretty much anywhere. But not everywhere. "We've got a pretty good knowledge of the region, so when people tell us where they live we can generally tell them whether or not a plant will do well with them," said Mary.

"We occasionally get people coming in from the middle of Exmoor and asking for this or that and when we find out where they're from we just have to tell them that the some things just won't do where they are.

"That's not the kind of advice you are likely to get from a garden centre."

Garden centres may be catering for a new generation of amateur gardeners but they do suffer from a depressing uniformity. Seen one, seen them all – and all the identical, but strictly limited ranges of plants they sell.

One of Triscombe's regular customers lives just 200 yards from one of the South West's best-known garden centres, but prefers to drive 40 miles to find the right number of varieties of any particular species to suit her planting schemes.

Within the walled garden and the various plant houses you will find 2,000 plant families alone represented.

Fancy an apple tree for the garden? Taking into account varieties and types – bush, standard, half-standard, espaliered, cordoned, fan-trained or stepover – and you have 720 to choose from. And Stuart and Mary can offer advice about each and every one. That's the result of more than 30 years' immersion in the business.

They run an enterprise based in what was once the walled kitchen garden of nearby Triscombe House but which was sold off, together with an adjoining house and an orchard, to pay death duties in 1954.

It then fell into the hands of Jeane Attwell, (who in her younger days had posed for the cherubic pictures painted by her artist aunt Mabel Lucy Attwell), her mother, and a friend, the motorbike-riding Dorothy Whitehead.

Jeane Attwell had been the first woman in London to sign up for the Women's Land Army and had got to know the West Country when she worked as a carter and gardener in Stockland, near Bridgwater. It was after running a nursery in Alcombe, Minehead, that she became involved in the great Triscombe project. And some project it was.

"The garden was like a wasteland," said Stuart. "It had been badly let go and it was totally overgrown. There was no man around to help and it took the three women about two years to clear it and start growing stuff and to get the first plants out: they were January King cabbages." With the ideal acid soil underfoot the trio made a first brave venture into soft fruit, but gave up after losing the first season's battle to the squirrels.

But they soon settled down to run a wholesale nursery, supplying shops as far afield as Evesham and Exeter with vegetable, herbaceous and alpine plants. Stuart arrived on the scene as a 19-year old on Decimalisation Day in 1970 and was pushed into the deep end right away.

"None of them wanted anything to do with the new currency and it was all left up to me: my first job was to go round and change all the labels," he said.

"Then it became clear that Miss Atwell didn't want to bother with the customers – she just wanted to get on and grow things. So that kind of thing was all handed over to me as well."

Mary arrived a year later after having worked at Nettlecombe Court, in the nearby Brendon Hills – but found there was a huge amount to learn.

"I really didn't know anything about the commercial side of the business," she said. "I used to stop up at night and swot and swot to learn all about the plants, and try to hang on to what I was learning."

Stuart and Mary married in 1975 and were soon so adept at running the business the owners simply left them in charge when they took holidays.

And when Miss Attwell died they were able to buy it, setting up on their own 23 years ago. But by the late 1980s running both a wholesale and a retail business was proving too much of a challenge, even with staff.

"We couldn't cope with the two sides of the business, and more and more customers were coming out to us. So we decided to go down the retail route – really because I like meeting and talking to people," said Stuart.

Triscombe is now rated among the top 75 plant centres in the country, with an almost unrivalled reputation for growing alpines. But the more you look around, the more marked the difference between this and the standard model garden centre becomes.

"We don't buy in plants, we grow them," says Stuart. "We take all our own cuttings, we graft all our own fruit trees – and we very rarely get a failure.

"And there's still quite a lot of heavy work involved: stuff has to be moved around by wheelbarrow, and it's all quite physical."

In fact, says Mary, you have to be prepared to literally put your back into it if you want to work at Triscombe – though from the length of service clocked up by the four staff, they evidently enjoy the experience.

"But it's as different as can be from an ordinary garden centre," she said.

"All the staff are interested in there is taking your money. Here, our staff can talk to people about the plants they are buying, give them advice and help. And that's what our customers really want – not piped music."