Sorbus
Many of the most colourful forms are plants collected on Asian hillsides and these demand good drainage in winter and cooler conditions - perhaps under taller trees. Those on heavy soil may struggle and they don’t generally do well in paving. If you can succeed, however, they make a fine winter spectacle as many hang onto their berries.
The easiest to grow
The Mountain Ash (Sorbus aucuparia) is a well-known tree with the common name of Rowan. It’s a British native (but is also found across Europe) and it bears clusters of orange-red berries that form by September. These are highly prized by birds so they rarely last into winter. The edible berries can also be used to make Rowan jelly. It’s very hardy and in Southern Europe it tends to grow in cooler, mountainous places.
The finest form is probably the variety known as edulis. This was introduced in the early 1800s and it’s a vigorous, medium sized tree with larger leaves and berries. There is a laciniate form (with lacy leaves) called 'Asplenifolia' and this pyramidal tree is often planted in parks.
The hybrid yellow-berried 'Joseph Rock' is thought to have aucuparia blood by some, but this is one sorbus to avoid. It is very prone to disease - including fireblight. This produced red lesions on the stems.
More of a challenge
These need good winter drainage and a sheltered site, but if you prepare the planting hole well and add lots of organic matter these trees should do well.
Heavy water-logged clay is a potential problem, but the victorians planted delicate trees like these on raised mounds.
Sorbus villmorinii AGM
This is a red-berried form originally collected by Abbe Delevay in 1889 in western China. The red berries fade to pink-white and match the purple-pink midribs on the green ferny leaves. Although prone to fireblight (a disease that attacks the shrubby and woody members of the rose family) a good specimen cannot beaten so it’s worth planting.
Sorbus commixta 'Embley' AGM (The Chinese Scarlet Rowan)
From Korea and Japan, this small columnar tree is tolerant of most soils and positions. The foliage colours up to burnt orange in autumn, making it unique among the berrying rowans. The clusters of red berries and pale, speckled bark are also features.
Sorbus hupehensis AGM
Discovered by Joseph Wilson in China and introduced into Britain in 1910, this rowan has distinctive grey-blue foliage and large clusters of white berries, sometimes tinged in pink. However, there are pink berried forms (like 'Pink Pagoda') that make stunning displays. The berries are rarely touched and the pink-berried forms looks splendid planted over plummy hellebores.
Sorbus cashmeriana AGM
A delicate tree with serrated leaflets and clusters of white berries held on red stems. The berries always last well into winter and early spring.
How to grow
- Buy a container-grown specimen from a good nursery and plant it in spring if possible - keeping it well watered fro the first growing season.
- Dig a planting hole the same depth as the pot, or the root ball of the tree, and loosen the soil in the bottom. The planting hole should be wide enough to leave a 20-cm gap when the tree is placed inside. In fact the larger the hole the better.
- Remove the pot and place the tree in the hole so that it is upright and the surface of the compost is flush with, or slightly raised above, the soil level of your site.
- Mix homemade compost or John Innes no 3 with the soil removed from the hole (a 50% mix of each) and refill around the tree, firm gently and remove excess soil, so that the bumpy graft union is not covered. If this rots the tree dies.
- Place the stake at an angle to the tree to avoid penetrating the root mass and knock in until it is firm, ensuring the top of the stake is adjacent to the tree. Tie the tree firmly to the stake using a buckled tree tie that can be adjusted. The stake should stay in place for a year but do check it regularly.
- Always water all newly-planted trees during hot, dry weather.
Suppliers
Ornamental Trees - www.ornamental-trees.co.uk
Barcham Trees - www.barcham.co.uk
Bluebell Nursery and Arboretum - www.bluebellnursery.com