As a garden writer I do try to keep up with plants old and new. However there is one trio that races ahead of me all the time — heucheras, tiarellas and their hybrids the heucherellas.

Just when I’ve told myself the darkest heuchera of all is ‘Osbidian’, I spot another that’s even blacker on the Plantagogo exhibit (tel 01270 820335/ www.plantagogo.com) at the Malvern Autumn Show. It’s called ‘Binoche’ and it’s new, well 2010. It was bred by Dirk Scheys who has a nursery in Belgium and named after the French actress Juliette Binoche. It’s part of a star-studded set that includes ‘Birkin’ and ‘Bardot’. Apparently ‘Binoche’ is not as dark as ‘Blackout’, also bred by Dirk Scheys, although this one passed me by.

I find it all very interesting that you get leaves that vary between the colour of coal, sweet tea, ginger, marmalade, pewter, silver or chocolate. Some have veins, or ruffles or crinkles. When I was a young gardener plant breeders like Alan Bloom were raising heucheras for their cut flower appeal. Now heucheras are foliage plants and very good ones too, whether in garden or container. Modern methods have given plant breeders advantages. They can look at DNA and assess whether two plants share the same number of chromosomes, in other words check their compatibility. They can use micropropagation to raise large numbers of plants quickly, by growing them in glass tubes under lights. Heucheras respond well to this system. However the initial process is still the same as it ever was. Plants have to be hybridised by hand and recorded. Seeds have to be sown and raised in the conventional way and then someone with an excellent eye has to evaluate thousands of them in order to identify three or four star performers.

Dan Heims, who co-owns the American nursery Terra Nova, is a heucheraholic. His team go through this process yearly “producing some of the highest priced compostable material ever created” to use his words. His book, co-written with Graham Ware, Heucheras and Heucherellas published by Timber Press, outlines the process of selecting and trialling. Once trialled in several countries, a name has to be thought of “with the aid of plenty of rum and Coke”, to quote the book. At the end of the day Dan Heims and his team need a good eye for a plant, just as Alan Bloom had, the will to do it.

Heucheras are also bred in France by Thierry Delabroye. Heuchera ‘Caramel’ is one of his best, and the golden leaves have red undersides. He is also the raiser of Geranium ‘Sandrine’, a golden-leaved hardy geranium with black-eyed, purple-pink flowers. It’s named after his wife, who spotted ‘Caramel’ as a seedling. I was in search of a Heuchera ‘Lime Rickey’ (Terra Nova 2004) at the Malvern Show, but the heuchera specialists have moved on to others including ‘Pear Crisp’. This crisply ruffled heuchera, with leaves the same yellow as a ripe pear, is one of a series from Terra Nova. I bought both and will use them in winter containers for I find winter light flatters heuchera foliage. The leaves do not fade in low temperatures, but now I have the challenge of finding something to go with them.

On balance, the ones with veined and marbled leaves are easier to place as they can be blended with other foliage plants.