It isn't obligatory to pop into Bettys Café when you go along to Harlow Carr Garden. However, there's no doubt that it's a pleasure when you visit the Royal Horticultural Society's most northerly outpost to sit by the window with a pot of tea and a sandwich or scone and look out on the visitors strolling around the cared-for landscape.

When we visited, in the middle of April, the gardens were in that waiting period between late winter and spring. Lots of work was going on. A new path was being laid through the Winter Garden, which runs from the Queen Mother's Lake to the main entrance. A fine, wide terrace and steps were being built from that entrance.

Some of the borders were waiting to be planted. A couple of the Gardens Through Time' were still in winter limbo. The wildflower meadow down by the bird hide had yet to reveal the glories it will become later.

But at any time of year there's plenty to see at Harlow Carr. The rhododendrons were a delight, as always. The trees were bursting into leaf, with red acers adding their glow to the fresh green of their neighbours. Along the side of the stream which runs through the edge of the woodland the spectacular skunk cabbage, named after the stench produced by its roots, produced dramatic splashes of yellow. Next to the outdoors café down by the Study Centre a bed of tulips, every one standing erect, attracted the eye with a jumble of colours.

By now the landscape will have changed. Planting will have taken place. So will germination and growth. The ever-changing face of Harlow Carr will have entered a new phase.

Streamside, for instance, will move on so that during June and July the edge of the water will be adorned with pink, mauve, purple and yellow candelabra primulas while at the end of July the Giant Himalayan cowslips will burst into spectacular bloom.

Elsewhere along the water's edge there will be a range of hostas growing alongside ornamental rhubarb and in the shade of Brazilian rhubarb, which produces the largest leaves of any outdoor plant grown in the UK.

The Queen Mother's Lake was constructed in 2002 and has provided Harlow Carr with a larger expanse of open water than the streams and ponds. Wildlife has moved in, in the shape of ducks and moorhens. The extensive planting on its bank is becoming established.

At one point the lake is overlooked by a white peak, a scale replica of the Eiger which is part of the popular Gardens Through Time feature reflecting the changes in gardening styles from the Regency period to the present day - the latter represented by Dairmud Gavin's "new tech" garden with its perennials and grasses viewed through a large round window in a fence and illustrating an age when outdoors living continues from daytime to night with the help of patio heaters and lighting.

We are fortunate to have this attraction within such easy reach of Bradford. For those who fancy themselves as gardeners, it's inspirational. Stroll around its paths and arbours and meander down its woodland trails and you come across neat labels advising you of the Latin and English names of plants you might never have seen before. And you'll see what can be achieved when those plants you have dotted around your own borders in ones or twos are clustered together.

For those who appreciate statistics and technicalities, here are a few. Harlow Carr Garden covers 58 acres (or 23 hectares) and is set 550ft (167 metres) above sea level in a shallow valley divided by Harlow Beck, alongside which runs the Streamside Garden.

The site is an exposed one, with a temperature range of minus 11C to 30C, giving an annual mean temperature of 7C. Frost can sometimes continue until early June and rainfall which can often exceed a metre a year can add to the problems of waterlogging, meaning the drainage needs constant attention.

The soil, above a bed of millstone grit, varies from silver sand to alluvial silt and very heavy clays which, without regular improvement can become baked hard in summer and sticky and waterlogged in winter. The sulphur springs in the area turn the soil dark and acidic in places, yet elsewhere it's neutral and even alkaline.

Such a variety of challenges! Yet thanks to the experience and expertise of the Harlow Carr gardeners they are able to turn them to their advantage and cultivate a wide range of plants in the land at their disposal.

The site was once the Forest of Knaresborough. The discovery of sulphur springs in 1734 led to its development a century later as a spa, with a hotel (now the Harrogate Arms) and a bath house which is now the home to the Study Centre close to the children's playground and bird hide.

Although the well heads in front of the bath house were capped off, the occasional whiff of sulphur escaping from beneath the Limestone Rock Garden serves as a reminder of the history of this area.

Harlow Carr Botanical Garden was opened in 1950, four years after the Northern Horticultural Society was formed with the aim of "promoting and developing the science, art and practice of horticulture with special reference to the conditions pertaining in the North of England".

The society leased 10.5 hectares of mixed woodland, pasture and arable land at Harlow Hill from Harrogate Corporation and the seeds of success were sown.

Factfile

RHS Garden Harlow Carr is in Crag Lane, Harrogate, off Otley Road (B6162) about a mile and a half from the town centre (tel: 01423 565418) and is open every day of the year except Christmas Day from 9.30am to 6pm (March to October) or 9.30am to 4pm (November to February). Last admission is one hour before closing.

Admission charges: RHS members free, adult non-members £6, students £2.20, children (six to 16) £2, under sixes free, groups of more than 10 £5 (group visits must be pre-booked on 01423 724690. There is a 400-space free car park.

Bus service 106 runs from Harrogate bus station every 20 minutes, Mondays to Saturdays, and every 30 minutes on Sundays in the summer. For details contact Harrogate and District Travel on 01423 566061. Alight at the end of Crag Lane, just a short walk from the garden entrance. Or trek to Harlow Carr from the centre of Harrogate via Valley Gardens.

Harlow Carr has a well-stocked plant shop to help you part with any cash you might have left after you've paid your admission charge and enjoyed a treat at Betty's.