|Official Plant Name||Salix|
|Native Area||Temperate Northern Hemisphere|
|When To Sow||January, February, March, November, December|
|Flowering Months||March, April|
|When To Prune||February, March|
Full Sun or Partial Shade
Exposed or Sheltered
1 – 12M+
1 – 8M+
Most soil types
Moist but well-drained
Willows are found in a remarkable variety of sizes and shapes, and they grow nearly the world over.
However, the vast majority are known only to botanists while several species are immensely popular, with a couple even being iconic trees.
It is these ‘essential’ Willows that we discuss. Willows are integral components of the British landscape, be it the forests or front gardens.
Willow: The Worldwide Tree
‘The Willow Tree’ as we know it is actually rather more than one tree – over a hundred in fact.
But that is far from all: Willow Trees are members of Genus Salix which comprises about 460 species. Many of them are shrubs, both erect and creeping.
Members of this genus are commonly supposed to be native to the sub-arctic and temperate regions of the Northern Hemisphere. In fact, Salix species are native to both hemispheres and all climatic zones from sub-arctic to tropical including equatorial.
Some or another species of Salix is native to nearly every country, and these include Willow Trees. For example, Humboldt’s Willow is native to South America and Cape Willow is native to Southern Africa.
Most Willow Trees, though, are native to Europe, and also northern Asia and a belt of land spanning the United States and Canada.
These deciduous trees are among the earliest ones to regenerate in spring, their pretty and colourful catkins that emerge in early April usually precede the leaves.
The leaves are almost always simple and alternate, and those of most species are lanceolate while some species have oval leaves.
Almost all Willows are dioecious meaning that a tree bears either male or female flowers, in the form of catkins.
Sizes, Shapes and Colours
Many Willow varieties are first-rate landscaping and architectural trees for any number of reasons.
These attractively-branching small to medium-large trees are shapely and elegant to begin with, and they are amenable to pruning and shaping.
Some species grow to over 15 metres while other varieties’ sizes are very much on the small side so they make perfect trees or large shrubs for small front yards.
Some species are pruned and trimmed to create living hedges.
Many varieties’ trees bend and sway while producing a melancholy sough as the wind rustles through them which is a quality not many trees share with the Willow.
And then there are those hues the foliage comes in – yellow-green, bright green, chalk green, pink, silvery, bronzy, and golden! Many species’ foliage also changes in shade with the season, usually becoming progressively deeper and warmer.
The various Willow species have weak wood and weaker wood. These trees are notorious for snapped limbs after a minor storm or even high winds.
But the flip side is that Willow wood is pliable with much more flex than other woods and it is also lightweight; indeed, a particular type of willow, Salix alba, is the only wood used for making cricket bats.
In addition, Willow is the wood of choice for baskets and wickerwork, and also for divining rods, wands, and woodcraft including sculpture.
Background and Origins
The Salix genus has existed since at least the late Cretaceous Period, making a home and habitat for itself in floodplains and riverine areas.
Millions of years later when the earliest humans arrived on the scene, they developed settlements along riparian and estuarine zones where they found an abundance of Willow trees.
They found the wood to be excellent for a number of uses – to build dwellings, make tool handles, weave baskets, and more, as confirmed by archaeological finds dating to 8000 B.C. and beyond in the ancient walled city of Ur, Sumer, by the Euphrates.
Thus, the first wood used by early humans to make their dwellings and utility objects at the dawn of civilization was probably that of a Willow.
Genus Salix shows its greatest diversity in temperate Europe, and the British Isles have had their own native species since the retreat of the glaciers at the close of The Great Ice Age 18,000 to 20,000 years ago.
These native species comprise four Willow Trees proper plus another four Salix shrubs.
S. Sepulcralis Chrysocoma – Golden Weeping Willow is one of the more robust Willow species, and is also one of the most aesthetic and popular. Those well-known ‘weeping’ branches dripping with weepy foliage, as it were, make a beautiful sight and more so because of the golden sheen that the young green leaves have, and which they revert to in autumn. A height of 8 to 10 metres is usual for this species but some specimens can grow to 15 metres. Uncommonly for Willows, this variety is usually monoecious though dioecious types are also found. RHS Award of Garden Merit.
S. babylonica var. pekinensis ‘Tortuosa’ – Dragon’s Claw Willow or Corkscrew Willow exhibits an upright habit but with a ‘twist:’ the limbs, branches and even the leaves are incredibly contorted and twisted as if they have been tortured, hence the name of the tree. Because of this rare attribute, it is the form and figure of the tree that is of sculptural interest; as a result, it is when the tree sheds its leaves in autumn that the very uncommon character of this tree comes into focus. It is relatively fast-growing and reaches a height of 12 to 15 metres.
(It bears mentioning that the extreme and extraordinary contrast that two species of the same genus, Weeping Willow and Tortured Willow, make with one another is unparalleled in the Plant Kingdom as one is entirely graceful and flowing and the other so impossibly gnarled and jagged.)
S. caprea – Goat Willow or Pussy Willow is one of the species native to the British Isles. It has two distinctive features. First, unlike most Willows this one has broad, oval leaves. Second, it produces fairly big, furry cream-grey catkins with the male ones being bigger and thicker. These bring to mind a cats’ tails, hence the tree’s informal name. It can be pruned to grow as a shrub though it is usually (fortunately) grown as a tree. It is on the small side, reaching a height of 8 to 12 metres.
S. alba – White Willow is a native of the British Isles where it is found in nature by riverbanks and other waterways. It has some interesting attributes and even more interesting habits. It is one of the fastest-growing Willows and also one of the largest, attaining heights between 20 and 25 metres at maturity. As a result, in high winds, even by Willow standards, its boughs break frequently. For this reason it is usually carefully pruned. Its narrowly lanceolate leaves, though of a dull, bluish-green hue, appear silvery-white from a distance, especially the undersides, and this effect gives this species its informal name. Slazenger, Gray-Nicolls, Duncan Fearnley, and Gunn & Moore all covet S. alba. Guess why?
S. integra ‘Hakuro Nishiki’ – Flamingo Willow is technically a shrub but makes the smallest of trees with an average height of 2 metres, topping out at 2.5 metres. The narrow, lanceolate leaves at up to 10 centimetres long further set off the small size of the tree. The defining characteristic of this highly ornamental tree is colours – and more colours. Fresh spring leaves are pink; as they mature they become variegated pink and green. At the same time its catkins are a creamy yellow or golden yellow. Summer foliage is predominantly green but with pink and creamy variegation. And when the leaves start to fall in autumn, you still get colour as the exposed branches are a rich bronzy reddish-orange. This little tree is ideal for a townhome’s courtyard garden. RHS Award of Garden Merit.
S. irrorata – Blue-Stem Willow, our last entry, is not really a ‘Willow Tree;’ rather, it must be called a Willow shrub. Tree or shrub, this species is also spectacular because of its season-long display of colours, and it too is an excellent choice for a townhome’s courtyard garden as it grows to only 2 to 2.5 metres with a spread of 3 to 4 metres. Numerous branches emerge from ground level. Even as they sprout they are of a light blue through lilac to lavender hue, a colouring it maintains in some or another shade through to autumn when it is particularly striking when the branches are bare. In late winter it bears small white flowers. Spring ushers in even more colours as this Willow produces grey catkins with prominent red anthers. RHS Award of Garden Merit.
Habitat and Growing Conditions
Other than Antarctica and Oceania, some or another species of Salix is found on every continent and nearly every region covering every climatic zone.
Where Willow Trees proper are concerned, they predominantly inhabit temperate zones in the Northern Hemisphere, particularly in Europe.
Their preferred habitat is a full sun location in moist ground, including heavy, damp soils. They are very frequently seen growing by or near water, from high banks of ponds and streams down to estuaries.
These trees are fully hardy in the United Kingdom, with the different species having hardiness ratings of H6 and H5.
Where to Plant Willows
Willow trees in the main should be planted in full sun and in consistently moist soil such as that by a brook or a pond.
It must be pointed out that an equally good question is, ‘Where not to plant Willows.’
Willow trees’ strong roots naturally seek out sources of water and they have been known to pierce and damage underground pipelines, sewage lines, and septic systems. So be sure to plant Willows at a healthy distance from such underground structures!
Where you should best plant a Willow Tree is entirely dependent on the species. Consider the Golden Weeping Willow and the Tortured Willow.
The traditional siting beside a stream or pond for a Weeping Willow is really the best one for it, and more so when it is accompanied by surrounding complementary greenery such as ferns and flower bushes.
It is a pastoral landscape tree. In distinct contrast, Tortured Willow is a rugged landscape tree, even an ‘accent tree’ with a ‘hard’ character. It should be planted in an isolated location all by itself where its form will stand out.
Flamingo Willow can be planted quite close to your dwelling where its attractive seasonal colours can be viewed from the bedroom windows as well as from the dining room.
Blue-Stem Willow could just as well be treated as an accent shrub and planted by the walkway near the front door for your guests to admire.
Feeding, Care and Growing Tips
The keys to growing thriving Willows are moist, even damp, soil and full sun exposure.
Willows flourish in fertile soils. A mixed loam, which may be heavyish, amended with organic compost is perfect for Willows.
A soil pH in the Moderately Acidic to Neutral range – 5.6 to 7.3 – is ideal though these trees will do quite well in even Strongly Acidic soil.
If, besides full sun, the planting site is by any waterway or pond, then that’s twice as much joy for the tree and less maintenance for you.
Many, though not all, Willows take root quite readily from cuttings. In end-spring to early summer, take a softwood cutting of 40 to 50 centimetres, and simply put it into moist soil of the type outlined above, be it in the open ground or a container.
Continue watering it, and when you see fresh shoots emerging you will know the cutting has taken root.
For the most part, though, Willow trees are propagated from young potted specimens bought year-round or bare-root plants bought from winter to spring from specialist nurseries.
Both forms are easy enough to (trans)plant. If planting a bare-root sapling, set it in a pail of water first and allow the roots to soak.
The planting hole should be deeper and wider than the root system. Spread out the roots, backfill the hole, and push and pack in the soil between and over the roots.
Give the new tree a generous watering, and ensure that it continues to get an ample supply of water.
Among trees, Willows number among the few that are happy feeders. An annual ‘treat’ of an organic, balanced slow-release fertilizer right at the start of spring will be beneficial to the tree’s new bloom.
Under normal circumstances Weeping Willows should not be pruned. Other Willow Trees may be pruned when they are young.
White Willow should be pruned for balance and with a view to the size-versus-strength ratio of each of its limbs.
A few Willow species are typically pollarded or coppiced, which is not a requirement but a choice.
Any pruning should be done during the winter when Willow trees are dormant; if they are pruned during their active, growing phase, they will bleed sap which is injurious to these trees’ health.
At the sapling stage select the most upright, strongest stem as the leader and prune the others. This will become the trunk of the tree.
In the second year and the following year, choose well-spaced branches that are ‘correctly’ growing upward at an angle. Prune branches that are close to the horizontal or to the vertical, and remove weaker or unhealthy branches that are crowding stronger ones.
As the tree grows keep a lookout for any shoots that develop off the trunk otherwise they will become unsightly branches near the bottom of the tree.
Very interestingly, Willows in the main are healthy trees that are not known to be unduly affected by pests and diseases but at the same time, the list of pests and diseases that can affect them is very long indeed.
The somewhat serious pests include aphids, gall mites, sawfly larvae, and willow scale. Caterpillars and flea beetles are the less serious problems that may affect these trees.
Most any variety of Willow can be sickened by willow anthracnose, scab, and rust diseases. In addition, a smaller number of varieties can also get willow heart rot, crown gall, honey fungus, root rot and tar spot.
The above ‘laundry list’, as it were, is not meant to alarm; it is provided only for the sake of completeness.
It should be noted that a particular variety will be more susceptible to one or another pest or disease whereas another variety will be more susceptible to some other pest and disease.
It would be wise to ask the seller exactly which pests and diseases you need to watch out for as to your particular variety of Willow Tree.
Where to Buy Willow Trees
Willow Trees, being very popular, are widely available at nurseries that sell shrubs and trees. Larger garden centres in your neighbourhood are sure to stock the varieties we have listed above.
Nurseries that specialise in trees commonly sell Willows online.
They are sold in bare-root form in winter and early spring, and as potted plants year-round.
Kersie learnt the basics of gardening as a toddler, courtesy of his grandfather. In his youth he was an active gardener with a preference for flowering plants. He is a professional and vocational writer and his freelance projects have spanned various kinds of writing.