Frost causes problems for all gardeners but it strikes an arctic chill into the heart of two thistle growers, as Bill Knox discovers

BILL and Joan McHugh have been casting frosty glances towards the weather forecast for weeks - but they are beginning to chill out a bit as their shot date approaches.

They are partners in Skipness Plants at Tarbert in Argyll and their exhibit at the National Gardening Show will launch their Arctic Glow, a new globe thistle plant, on to the horticultural scene - despite the frosts which have threatened it.

They know it may not be at its peak, but hope things will be better than last year: ''We had a frost during the second week of May. It wiped out many of the plants we had nursed along for months towards the Strathclyde target. By some frantic switching around we managed to still have a display - but it was nothing like what we had planned,'' said Bill.

''Many exhibitors suffered. There is nothing easy about preparing for a show. It can take months of careful calculating and tending. Then just one night of frost can destroy a lot of hopes.''

It is 11 years since the Glasgow couple came to Skipness, seven miles south of Tarbert on the Loch Fyne road to Campbeltown. He had been working in England after having gained years of experience with Glasgow Parks Department and Auchencruive College in Ayrshire.

''I had been seeking a place where I could establish my own plant nursery business. At Skipness I found exactly what I wanted.

''It was an old walled garden of one and a half acres. It was overgrown, but ideal.

''After that, it was mainly a matter of getting to work on it.''

Today Skipness Plants of Argyll supplies thousands of plants, to customers. It has 1500 different varieties and one of its main strengths is that damp, mild weather - if the frost stays away at the right times.

The new globe thistle originated in the United States - the Argyll plants came from seed obtained in Germany. A striking plant, with grey foliage, it has white flowers in June and in August and experts praise it as a good example of the Skipness enterprise's specialisation in plants, shrubs and climbers not usually found in garden centres.

''We will also be introducing another plant to horticultural enthusiasts,'' promised Bill. ''It is Campion Silene dioca Clifford Moor, and we are the only Scottish nursery raising this plant.

''It was first found as a natural variation in Yorkshire, a plant which has striking gold foliage and which grows to a height of about 50 cm. The flowers are an attractive pink and we are releasing it for the first time at the show.''

Other plants to be featured in the Skipness exhibit in one of the floral marquees will include a range of eryndiums, timed to show both foliage and flowers.

''Getting our plants to Strathclyde Park means a 115-mile journey from our base,'' said Bill. ''But we found, as did everyone in horticulture, that last year's event was a huge step forward. Business was good and using the same formula of innovation and high quality we think we can look forward to another winning event.''