The ash with plenty of dash
With vibrant leaves and beautiful berries, the rowan’s a real autumn dazzler
YEARS ago, my parents decided to nurture my love of the natural world by giving me I-Spy Trees, a spotters’ guide to 45 species found in Britain.
Common oak, silver birch, elder and a host of others that flourished in the countryside around our East Midlands home were soon ticked off, but I had to wait until we went on a family holiday to North Wales to snag the evocatively named mountain ash.
It was autumn, and the dense bunches of brilliant red berries were displayed on branches clothed with leaves that had turned fiery shades of yellow, orange and red.
Mountain ash, or Sorbus aucuparia, is native to our shores, and found largely in the north and west of the country. Its relative obscurity on our landscape, and its good looks, struck a chord with my younger self, and it’s been my favourite native tree ever since. In fact, I even fought hard to call my baby daughter Rowan – a colloquial name for this tree – but I was overruled by my wife, and our daughter became Lily.
Our native mountain ash is the parent of numerous ornamental hybrids and belongs to a large family of highly decorative trees from overseas. These all have pretty white flowers in spring but are most valued for their autumn foliage and clusters of berries in shades of white, yellow, pink, orange, red and brown.
These deciduous beauties look good at the tail end of the year, and if you plant them now, you can enjoy a spectacular autumn finale for several decades to come. Containergrown and bare-root specimens will establish quickly in moist soil, forming roots that will enable them to romp away in spring.
Introduced during the 1950s, Sorbus aucuparia ‘Sheerwater Seedling’ is a splendid form of our indigenous mountain ash with heads of scented white flowers in spring followed by clusters of orange-red fruit. Eventually growing to about 20ft, this tree is good for restricted spaces due to its upright habit.
Another superb red-berried form is S. commixta ‘Embley’, a small tree from Japan and Korea. Aptly named S. commixta ‘Olympic Flame’ has a compact, columnar habit with orange-red berries and leaves that take on fiery tints in autumn. Once known as ‘Dodong’, it was renamed for the 2012 London Olympics.
S. aucuparia var. xanthocarpa (sometimes sold as ‘Fructu Luteo’) boasts orangeyellow fruit. It has a broad, rounded head of branches and will reach 25ft within 20 years or so. Victorian gardeners were clearly impressed, as the tree was awarded the Royal Horticultural Society’s Award of Merit back in 1895.
The most popular yellow-fruited mountain ash has long been Sorbus ‘Joseph Rock’, which also has feathery foliage that turns crimson, purple and gold when temperatures nosedive. ‘Sunshine’ is a worthy successor thanks to its larger and even longer-lasting fruit.
The first time I clocked S. cashmeriana, I didn’t realise it was a mountain ash as I was so used to seeing varieties with red or orange berries – this species from Kashmir boasts marble-size, snowy-white fruit that can last until spring. Fairly slow-growing, it will reach 16ft and has leaflets that turn gold before falling. Mountain ash trees prefer fairly fertile, well-drained soil in sun or dappled shade. Larger ones make excellent specimens for lawns or can be planted with other trees and shrubs in a woodland-style garden. Shorter varieties are perfect at the back of a border or in the middle of a bed.
Planting container-grown ones is easy. Dig a round hole that’s about twice the diameter of the container and the same depth. Spike the sides and bottom with a garden fork to allow roots to penetrate easily. Place the tree in the centre and fill the gaps with soil, firming down as you go.
BARE-ROOT specimens need planting at the same depth as they were growing before being lifted from the ground – there should be an obvious ‘tide mark’ of soil on the trunk. Dig a hole that’s twice the diameter of the root system and deep enough so the mark lines up with the surface.
After planting and filling the hole with the excavated soil, give the ground a good soaking. Spread a 3in layer of bark, leafmould or garden compost over the surface to lock in moisture and prevent weeds growing. Keep the mulch clear of the trunk, though.
For the best display of berries, feed trees with a high-potash fertiliser in spring and midsummer to encourage flowers and fruiting. It’s not necessary to water mature specimens, but young trees need plenty of moisture.