Salix is a hugely diverse genus of deciduous tree and shrubs. They range from large trees such as the weeping willows down to species that suit being planted in a rock garden. They can offer attractive foliage, catkins and some have coloured winter stems, which, like Cornus, are produced when plants are annually coppiced.
The most well-known is S. × sepulcralis var. chrysocoma Award of Garden Merit (AGM), perhaps not known so much by its long Latin name but as the weeping willow.
A hybrid of S. alba var. vitellina and S. babylonica, it has inherited frost hardiness and golden shoots from alba and the strong weeping habit of babylonica. It is often seen planted next to streams and ponds, where it thrives in damp or wet soil. The reflections cast by the leaves in water are a beautiful sight.
Some closely related varieties provide highly decorative contorted branches that are a real treat in winter because they provide a striking silhouette. S. babylonica var. pekinensis ‘Tortuosa’ (syn. S. matsudana ‘Tortuosa’) is perhaps the most impressive, a medium-sized tree with bright-green leaves, while S. × sepulcralis ‘Erythroflexuosa’ AGM is a much smaller tree and has paler green leaves with juvenile orangey/yellow shoots.
Several Salix produce lovely coloured shoots after being coppiced. One of the best is S. alba var. vitellina ‘Yelverton’ AGM, which has vibrant reddy/orange or yellowy/orange stems. Another closely related variety is S. alba ‘Britzensis’, with bright-red young shoots. S. alba ‘Chermesina’ offers a strong reddy/orange, while S. daphnoides has lovely dark-purple shoots with a silvery bloom.
Other Salix offer attractive foliage. Some of the finest of these are the fine-leaved S. exigua AGM and S. elaeagnos subsp. angustifolia AGM, also known as the narrow-leaved olive willow.
While some species such as the weeping willow prefer damp or wet soil, generally Salix will grow well in most soils apart from dry ones. S. caprea and S. purpurea are exceptions that can cope with dry sites. Species range from fully to frost hardy and most like a position in full sun. Plants usually only bear catkins of one sex, and it has to be said that male catkins are usually more striking than the females — how different to humans.
Plants being grown for their colourful winter shoots or juvenile foliage should be cut back hard in early spring, every one-to-three years. Propagation can be carried out by semi-ripe cuttings in the summer or hardwood cuttings in winter.
What the specialists say
Vince Edwards, key account manager, Coles Nurseries, Leicester
"Salix is a generally easy crop to grow but larger examples of named forms have a high-value return for the grower. Unfortunately at present they have a limited appeal within the landscape design sector. Its use is primarily limited to plantings in parks and other public open space.
"The species or varieties that stand out for me are the more decorative forms. S. ‘Chermesina’ and S. daphnoides are both very useful trees that add effect and colour to the landscape.
Specimens of the more interesting named forms can also be used as shrubs and should perhaps feature in greater numbers, including vitellina, caprea, elaeagnos and matsudana ‘Tortuosa’. These all have interesting features and effects that can and should be used more in larger landscape schemes.
"Perhaps the lack of use is more related to the issues and concerns that poor maintenance schedules have on the design and long-term visual effect of the area in which they are planted.
"As a genus Salix is pretty tough and suited to our climate and environment. Powdery mildew, canker and scab can be issues but not of sufficient cause to not specify and select the use of Salix."
Robert Player, proprietor, Garden Associates, Central London/Hertfordshire
"From more than 300 species, ranging from the tropics to the Arctic, including 19 natives, from 3cm to 30m-plus high, the only willow that seems to be universally recognised is S. alba ‘Tristis’, the weeping willow. There is no other tree in any of my gardens that has such an emotive following — it is simply loved by all. Possibly it’s the graceful movement, swaying in the wind, or maybe it’s simply a tree that everybody knows and recognises.
"However, this very large and diverse genus, early to flush and late to drop, for me is all about catkins and twigs. This genus requires moisture in any form, so the gravelly nature of central London is not ideal without a handy lake, but entering the heavier clay soils north of Hyde Park, once established Salix thrive.
"We grow and coppice S. alba ‘Chermesina’ syn. ‘Britzensis’, which produces up to 3m of brilliant orangey/red wands in a season.
S. alba vitellina does the same in a vibrant yellow and S. daphnoides more of a dull purple. These, used in conjunction with dogwoods, bring the winter landscape alive.
"Also for winter framework there is the contorted willow or dragon’s claw, S. matsudana ‘Tortuosa’ from China. Its twisted and contorted branches are a showstopper. To propagate, snap off a small branch, leave it in a bucket of water and, hey presto, roots appear in no time.
"We successfully grow Salix from the mighty ‘Tristis’ to the short, stocky S. hastata ‘Wehrhahnii’, but never, never that little horror (in my opinion) S. caprea pendula — a top worked pendulous small ‘tree’ that is agreeable when covered in catkins but a magnet for willow canker and dieback. I am not a fan.
"Willows should be grown in the hope to attract the Large Willow Aphid. If you have not seen one then put it on your bucket list. They are huge, like small bats. You can see them looking back at you and saying: ‘Go on, spray me — if you dare.’"
Species and varieties
S. babylonica var. pekinensis ‘Tortuosa’ (syn. S. matsudana ‘Tortuosa’) is the highly attractive twisted willow that has contorted stems. Its leaves are a lovely bright green and it produces yellow/green catkins. It is a hardy, fast-growing and upright tree. Height: 15m. Spread: 8m.
S. caprea, the pussy or goat willow, is a UK native with great importance for wildlife. It becomes a hardy, short-trunked tree, usually only reaching 5m in height, that retains its shrubby nature. Trees are male or female with different catkins — slender light-green females or silky grey bud-like males with showy golden anthers. Tolerates drier conditions than most willows. Height: 5-10m. Spread: 3-6m.
S. caprea ‘Kilmarnock’ is a popular weeping form of the goat willow that has a dense head of yellow/brown shoots. It produces broadly elliptic, toothed leaves that are dark-green above and grey/green beneath. Grey male catkins appear on bare shoots in mid spring. Height and spread: 1.5-2m.
S. elaeagnos subsp. angustifolia AGM (H5) (syn. S. incana), or the hoary willow, is a hardy, upright shrub with rosemary-like long leaves that are green/grey when young and turn yellow in the autumn. Sender green catkins are produced with the leaves. Height: 3m. Spread: 5m.
S. exigua AGM (H5), the coyote willow, is a hardy, large, branching shrub with lovely silvery/grey leaves and slender catkins produced in the spring. Unlike many other willows it prefers a dry, well-drained soil and can fail in very wet areas. Height and spread: 3-4m.
S. integra ‘Hakuro-nishiki’ AGM, the flamingo willow, is a very popular dwarf, weeping Japanese willow tree. Often seen grown as a standard in front gardens or on patios, it bears slender yellow catkins in early spring, then creamy pink variegated leaves unfurl and last through to autumn. After the leaves have fallen, the orange stems look good throughout the winter.
S. purpurea ‘Nancy Saunders’ AGM is a lovely willow with glossy maroon shoots, soft-blue/grey leaves and small silver catkins in spring. Will become a large branching shrub if left unpruned but often coppiced to produce fresh new shoots. Height and spread: 4m (2m if coppiced).
S. × sepulcralis var. chrysocoma AGM (H5) (syn. S. alba ‘Tristis’) is the most widely grown weeping willow, a fast-growing tree that forms an elegant weeping dome once established. It has pale-green narrow leaves borne on golden yellow shoots that slowly darken to brown as they mature. Plant next to a stream or pond, where it will thrive in damp soil. Height and spread: 15m.
S. × sepulcralis ‘Erythroflexuosa’ AGM (H5) is another form that features striking contorted
branches. It is a small tree that bears pale-green narrow leaves on young orange/yellow stems that fade to brown as they mature. Height: 5m. Spread: 3m (or cut back to 30cm every spring for colourful and contorted new growth).
Thank you to Floramedia, which supplied the images for this article from its photo library