The annual Gardening Scotland show is a must for keen gardeners and this year's was no exception.

Whether as an exhibitor, a speaker or wearing my Herald hat, I've been going ever since the event's inception. No longer do exhibitors set up shop in a converted cattle shed, as I did in the early days. Congratulations are due to Jim Jermyn and his team for their resourceful work over the years.

People visit Gardening Scotland to learn and be inspired. For most, the show gardens are the high point, crammed with ideas for good design, colour combinations and plant varieties. I enjoyed the Garden of Hope - A Pathway To Healing and The Lost Gardeners Of The Great War, but my favourite was The Perennial Garden. Designers Amber and Martin Crowley thoroughly deserved their gold medal and best-in-show awards.

The garden commemorates the 175th anniversary of Perennial, the charity for gardeners in need. Its logo, the arum lily, was represented at the back of the garden by two towering steel lilies and the troubled life of the gardeners was illustrated by dark, velvety purple alliums and spiky, near-black foliage. As the gardeners recovered, colours softened and lightened near the front. Astilbes, oriental poppies, geraniums, salvias and many others blended with and were contrasted by a striking blend of foliage.

In other gardens, though, there was far too much concrete and decking, hard landscaping seeming more important than the few frightened plants that looked like an afterthought. Some designers used improbable plantings for visual effect, but rhododendrons and lavender stoechas, for example, simply could not co-exist in the real world. The artistic effect was good, but gardeners looking for ideas might go away thinking they could grow acid and alkaline-loving plants next to each other.

Since Gardening Scotland is Scotland's largest flower show, it should highlight plants and techniques best suited to this country. Even though most exhibitors came from the south, the leading Scottish nurseries - Macplants, Binny's, Kevock and Glendoick - showcased what's best for Scotland. They raise their stock here, so you can be confident the plants will cope with your growing conditions, either outdoors or under protection. These experts can also advise on plant suitability, how a plant will grow and to what height.

Tweed Valley Fruit Trees is another gem for Scottish gardeners. Nick Edwardson established his business near Innerleithen in the Scottish Borders two years ago and has built up an impressive collection of apple trees along with some pears, plums and damsons. Almost a third of his apples are Scottish heritage varieties, so he's a worthy successor to John Butterworth, whose nursery closed a few years ago.

It's always fun finding new or unusual gardening aids or products. Slate, a popular material at the moment, was not only a key element in The Perennial Garden, but I came across two firms offering recycled slate pots and ornaments. Two years ago, Jeanette and Gerard Van Der Veen had a mass of old slates after re-roofing their house so they started making bird boxes. After establishing their firm, Slate And Nature, they began designing feeders, nests and even a letterbox.

I then chanced upon a slater, Martin Willcocks. During the snowy winter of 2012 he couldn't work on roofs, so he kept his squad busy making slate pot holders. He's now developed a sideline: Fifty Shades Of Slate. Sounds like a novel form of recycling.

And finally, you may remember I declared this the Year of the Thistle to mark our big vote in September. So, you can imagine my delight when I saw the ornamental thistle, Cirsium rivulare "Atropurpureum", in several show gardens and on nearly every flower stand. This is hopefully a sign of things to come.