The many varieties of Sorbus – both mountain ash and Swedish whitebeam – have bestowed clusters of flowers, colourful leaves and striking berries on Rosemary Verey’s Gloucestershire garden. Here she selects some of her favourites.
Now and the next two months are the best times to plant trees in your garden, so they have enough time for their roots to settle before the hard weather sets in. Make your selection from a catalogue or by visiting a good nursery. One visit is worth 100 catalogues, but anyone anticipating planting new trees will have looked around and taken notes.
We have been delighted with the Sorbus we were advised to plant on our alkaline soil (limestone), in the Cotswolds. The Sorbus family divides into two sections, the mountain ash (aucuparia) with pinnate leaves and the Swedish whitebeam (aria) with simple leaves.
They are a wise choice for drier conditions and even poor soil. They give major interest in spring with their flowers, in summer they provide shade so are ideal lawn trees, and in autumn their berries and leaves provide a diversity of colour.
I do not recommend our native mountain ash or rowan for the garden, the berries ripen in August and the birds will immediately steal them. My two selections with red berries are Sorbus commixta ‘Embley’ (left) (AGM), an upright 6-7 metre tree with outstanding and long-lasting colour in October and November and generous clusters of orange-red berries.
S. sargentiana, named for Charles Sprague Sargent, director of the Arnold Arboretum in Boston, has pinnate leaves up to 12 inches long, with 6-inch leaflets. These turn brilliant vermilion tones in late autumn. The bunches of scarlet berries are huge: I’ve counted up to 400 in a single cluster. Find a specimen with branches coming from near the ground, so you can appreciate the berries at eye level.
Joseph Rock went plant hunting in China, around 1900, for Professor Sargent, and brought back a yellow-berried form – named S. ‘Joseph Rock’ (AGM). It fruits reliably every autumn, and the birds ignore them until food is scarce.
Do include S. cashmiriana, an upright 5-6 metre tree with fern-like leaves and large pure white berries. In our garden the birds tend to peck and drop them.
S. hupehensis (AGM) is different in that its foliage has a grey tinge, looking silvery in sunlight. The berries start pink, turning to white. It is too large for a small lawn, but does well used as a windbreak or to hide an ugly building, or in a Sorbus collection.
My last choice is S. vilmorinii (AGM). Catalogues tell you it will grow to 6 metres, but on our poor Cotswold soil it has remained small, only 3 metres, so we can appreciate the clusters of pendulous berries (below). These start rosy red, changing to pink and then to white. It fascinates visitors when all these colours show simultaneously!
In the aria section, the Swedish whitebeams have simple, ovate leaves. In spring S. aria ‘Lutescens’ (AGM) is striking in the distance with silvery leaves looking like flowers. Later they turn green with grey undersides. The fruits are cherry like.
Sorbus latifolia, the ‘Service tree of Fontainbleau’ is broad-headed with russet-yellow berries. You can see S. l. ‘Mitchellii’ (AGM) at the Westonbirt Arboretum, Gloucestershire. This whitebeam was discovered by the late Alan Mitchell. It has a rounded head and reaches 8-10 metres, and is distinct for its massive leaves, about 15 cm each way. I used S. ‘Leonard Sprenger’ in a tree planting for friends and they are delighted with the large flowerheads and great clusters of orange-red fruits.
General thoughts when buying and planting trees:
1. Ask the nursery to mark on the trunk which side faces south
2. Dig a square hole (not round) and loosen the sides with a fork
3. Have enough good compost in a wheelbarrow, also a stake/s, and ties
4. Lay a stake across your hole to mark the ultimate level of the soil – this is to guide you for depth when planting
5. Spread the roots out and carefully place the stake to avoid these
6. Infill with compost, allowing this to filter between the roots, firming often
7. Secure the main stem to the stake/s
8. When planting in grass allow enough open soil around the trunk to prevent mower damage
9. Water well then either lay flat stones or carpet around the trunk to retain moisture
Note: AGM = Royal Horticultural Society Award of Garden Merit
See also the Helping Hands workshop:
How to plant and stake a tree
How to store bare rooted trees