The best plant cultivars old and new
Words: Graham Rice
In the Plant Heritage Marquee, a fascinating cross section from Britain's living library of garden plants is on display. The Plant Heritage National Collections, each devoted to just one type of plant, aim to keep examples of modern varieties, classic varieties, and old and overlooked varieties of the focus plant. No one wants good plants to be lost forever.
So for the National Collection of Hostas Mickfield Hostas have gathered more than 2000 cultivars, and they’re adding to them at the rate of about 150 a year. That's a lot of hostas. But it's important to keep all the old ones to preserve the gene pool which can be used in developing new cultivars. And when new ones appear, they can be compared with older varieties to make sure that they really are different.
There are thousands of wild species of Rubus – that's the genus that includes blackberries and raspberries as well as some lovely ground cover plants and other species with attractive white winter stems. Barry Clarke's collection covers most of these and he's adding to it by collecting species from the wild – he is just back from Taiwan with more than 30 species for the collection.
This shows another important use of a National Collection, keeping a collection of species from around the world to assess their value in British gardens and use them to develop new cultivars.
The National Collection of Malmaison Carnations illustrates another important role. Jim Marshall has single-handedly revived interest in these deliciously fragrant carnations, so much so that they've gone from rarely being grown at all to cut blooms being sold in supermarkets. For although their fragrance is impressive, the flowers are rather messy so the neater perpetual flowering carnations took over.
Jim also has a collection of early perpetual flowering carnations. One of them, brick red 'Duchesse of Norfolk', which arose at Floors Castle near Kelso in Scotland in 1937, developed a sport, a natural mutation. The sport is pure white and Jim named it 'Earl Kelso', one of the other titles of the Duke of Roxburghe whose home is Floors Castle.
This illustrates another way in which National Collections can be valuable as new varieties arise in the style of historic varieties held in the Collection.
The Plantagogo National Collection of Heuchera aims to prevent the need to rescue old cultivars that start to disappear as new cultivars become more popular. There's been a vast flurry of new heucheras in recent years and Plantagogo are not only collecting new introductions as they come out but have also collected together all their predecessors. They are also making the earlier cultivars available for sale so collectors and gardeners can buy them easily so making it less likely that they will ever disappear.
Finally, it's important to remember that National Collection holders can be all sorts of people from keen home gardeners to HRH The Prince of Wales, from nurseries to National Trust gardens and private gardens large and small. But clearly, trees and shrubs present a special challenge simply because the plants are so large.
The Sir Harold Hillier Garden, for example, has 12 collections including oaks and pines – and you need a lot of room to collect trees like that. But, in its way, the small collection of Veratrum held by Shrewsbury gardener Margaret Owen is an important as Prince Charles's beeches or those 2000 hostas.