Weeping trees
For those who love the shape and form of weeping trees, Mary Lovell-Smith explains the scientific reason why some trees grow down rather than up, and suggests great weeping trees and shrubs for your place.
Best varieties for New Zealand gardens.
despite their rather mournful name, weeping trees can add much joy to a garden. Consider the sublime beauty of arguably the most famous cascading tree, the weeping willow. Or the majesty of another humped behemoth, the weeping elm found in older suburbs, towns, parks and botanic gardens up and down the country.
These two examples can get large, but because weepers grow down rather than up, many remain as small trees, perfect in smaller modern-day gardens.
Although this pendulous growth habit is found in nature, most ornamental weeping trees are cultivars originating from a genetic mutation. More than 75 genera include weepers; from larches and other conifers to apricots, ashes and birches. As such, they seldom run true to seed and must be propagated vegetatively.
Weeping willows have been cloned for centuries. In comparison, we have been cloning the weeping swamp cypress ( Taxodium distichum ‘Cascade Falls’) for a mere decade or two in New Zealand, according to Pip McVicar of New Plymouth’s specialist conifer nursery, Cedar Lodge. Pip says that a weeping sport of the southeast United States’ native swamp cypress was discovered in Auckland in the late 1990s by nurseryman Graeme Platt – and all ‘Cascade Falls’ come from this one plant.
Why plants weep is still open to conjecture. Boston botanist Peter Del Tredici, in an article in the New York Times, says he believes it is caused by the single dominant growing point which enables plants’ trunks to grow straight up being disrupted, and the trees develop by superimposing one layer of horizontal growth on top of the previous one.
Another theory holds that lignification, a process which strengthens the plant vascular body, giving the tree rigidity, is delayed in these mutations, allowing gravity to set in before the stems have time to stiffen.
Because the species is usually more vigorous than the mutation, weeping trees are often grafted onto species rootstock.
Hamilton’s Wairere Nursery stocks several varieties. Owner Lloyd Houghton says most are grafted onto seedlings of the same species almost at ground level (known as low-worked or L/W).
“Every now and then we get high-worked standard (H/W), which are grafted at set heights on a pole like rootstock,” he adds.
He says that the advantage of H/W grafting is that the tree trunk is created immediately, rather than the gardeners having to remove the lower branches to create their own bare tree trunk over the ensuing years.
The higher the graft the more pronounced the weeping. Conversely, some weepers if left to their own ungrafted devices will do what can only be described as crawl – with nowhere to droop to, the branches spread outward. The likes of Pinus densiflora ‘Pendula’, the weeping Japanese pine, were popular in 1950s rock gardens, often reaching 2m or more across, with a height of only 30cm.
Between these prostrate pines and the mighty weeping redwood Sequoia sempervirens ‘Pendula’, which can
Although weepiness is found in nature, most ornamental weeping trees are cultivars originating from a genetic mutation.
reach 50m high, are a myriad other weepers of many shapes, sizes, forms, colours and habits, both deciduous and evergreen.
What they do share apart from their pendulosity is a propensity to be the star in a garden, whatever your style.
To incorporate them successfully with other plants takes some thought however.
“Never crowd them,” is the advice of Christchurch landscape architect Emily Hastie of Kamo Marsh Landscape Architects. “Weeping trees need breathing space. They are often sculptural and thus the statement piece, the feature. You would not want to cram other plants around or underneath them,” she says.
Also, “as weeping plants tend to lead the eye down, particular care should be taken when choosing the groundcover or any smaller plants beneath it.”
Long-time weeper devotee Lloyd Houghton says the trees often go well near ponds, where their appearance not only leads the eye down but the water emphasises their cascading aspect.
He says their size also makes them useful for planting under power lines or windows, and of course in pots.
While Lloyd and Emily predominantly use weepers as specimen trees, both confess they like sometimes to group the trees together. “It can be effective and fun creating layers with several, for example, different weeping and horizontal maples to create a living art piece,” says Emily.
Lloyd suggests grouping the same weeping plant at differing heights.
Keeping a weeping tree in shape will require pruning, and while different species have different requirements, generally the theory is to prune to enhance its natural cascading form. This usually entails cutting out unruly and wayward up and outward growth, thinning branches and lifting what is known as the curtain (the cascading branches) to reveal the trunk.
How high to lift the curtain is up to the gardener’s discretion but failure to do so at all may mean the tree will end up looking like what Lloyd describes as “a blob” and with no structure.
Mind you, some weepers, particularly conifers, have a charm of their own when left with no visible trunk – rather like a yeti or other strange creatures. It’s all a matter of individual taste, of course.
“As weeping plants tend to lead the eye down, particular care should be taken when choosing the groundcover or any smaller plants beneath it.”
1 Cool conifer
For a real curiosity, try a well-trained weeping blue Atlas cedar ( Cedrus atlantica ‘Glauca Pendula’). Slow growing and sinuous, it could grow to 3m or so in 10 years but also up to 7m wide, its drooping needles often resembling a waterfall.
It would be a novel and effective way of screening off anything from neighbours to an unsightly eyesore. Support is necessary for training but once the trunk and branches are sturdy enough, it may be removed.
Plant in full sun.
2 Local treats
Endangered in the wild and often difficult to buy, but well worth persevering in the pursuit of, is our native weeping broom Carmichaelia stevensonii. Found naturally only in the Awatere, Wairau and Clarence river valleys of southern Marlborough, this small tree has little but showy pale lavender-coloured flowers produced in summer on weeping leafless branches. It grows in a variety of free-draining soils, but will only flower well in full sun.
Eye-catching, too, is the yellow rimu ( Dacrydium cupressinum ‘Charisma’) discovered by Taranaki nurseryman Vance Hooper. Much smaller than a regular rimu, this weeper will only reach about 2.5m in 10 years. Give it rich moist soil, shade and shelter from strong winds when young.
3 Silver lining
Vita Sackville-West used the weeping silver pear ( Pyrus salicifolia ‘Pendula’) to cloak a statue of the Virgin Mary in her White Garden. Enough said. Its narrow grey-green leaves lined in a downy silver and clusters of single white flowers in spring have made it a long-time favourite of gardeners. Growing to 3-4m high (depending on the height of the graft) and a similar spread, it is useful in small to medium gardens as a specimen, or in larger ones as a romantic avenue. Its lustrous pale tones are enhanced when planted against a dark background.
It likes good, well-drained soil in full sun and is wind tolerant.
4Ace acers
Graceful weeping maples are perfect for small gardens, with many only growing to 1m high by 1m wide plus they look fab in pots.
Most of these weepers are Acer palmatum dissectum cultivars, whose graceful pendulous branches are clothed in finely dissected leaves. The range of these means the biggest problem is not finding one you like, but choosing one of the many you like. Colourwise, there seems no end of choice, from moody purples and hot pinks to bicoloured sunsets to brilliant greens – and that’s not even talking about their autumn splendour. The foliage of most common green-leafed forms starts off lime in spring, deepens to emerald over summer, before turning copper, purple and finally a fiery red.
These maples are happiest in the morning sun to light shade, and sheltered from harsh winds.
5Kiwi classic
Young specimens of weeping elm ( Ulmus glabra ‘Camperdownii’) and Ulmus glabra ‘Pendula’), are becoming increasingly rare, more’s the pity. They are magnificent, as when fully grown, they can reach up to 7m high by 7m in diameter (creating magical secret rooms under their dense canopies). But they are just as charming when young. Just choose your spot thoughtfully, for though you may not live to see it in 60 years, you want future generations to be able to enjoy it.
Plant in full sun, and medium to light soil. Elms take any amount of pruning with little apparent effect.
6Pip’s pick
Pip McVicar of New Plymouth’s Cedar Lodge Nursery says while the nursery stocks six different weeping conifers, her top choice might just be Taxodium distichum ‘Cascade Falls’, the weeping swamp cypress.
Why? “It’s just really good. It’s burnished all the way to the ground. It has beautiful soft green cascading foliage in early spring and a lovely colour change in autumn when it turns a bright orange.”
It won’t grow any taller than the 1.5m rootstock on which it is grafted, and is easily trained along fences. Pip recommends only pruning it should, say, you want it narrower.
While it will grow very close to water, such as on the side of a pond, it doesn’t need to, she says.
7Downward facing dog
For a floral extravaganza, you could always head for the weeping flowering cherries. But why not go for a more sophisticated flowering weeper such as the dogwood Cornus florida ‘Pendula’ and the slightly more floriferous Cornus kousa ‘Elizabeth Lustgarten’.
A delight in spring when their starry white flower bracts dot the fresh new leaves, both are small, graceful trees, growing only to 2.5m high. If you love those dogwoods with their horizontally layered branches, don’t be surprised to find these unusual weeping forms creeping into your list of favourites.
Plant in the sun in rich soil.
8Stranger things
Wairere Nursery’s Lloyd Houghton likes the unusual, which is why, he says, he is such a big fan of weepers. When pressed for a favourite, he reluctantly settles on two, the weeping mulberry Morus alba ‘Pendula’ (his own is a stately 35 years old) and the Japanese pagoda tree Sophora japonica ‘Pendula’.
With large, glossy heart-shaped leaves, edible fruits (loved by birds and humans) and strongly weeping habit, the mulberry deserves plenty of room to spread, says Lloyd. It can reach more than 8m.
Give it full sun in rich, moist soil. Lloyd describes the pagoda tree – with its deep green oval leaflets which turn soft yellow in autumn and creamy pea-like flowers in summer – as simply stunning.
Although this statuesque beauty grows readily in most spots with good soil, sun is necessary for flowering. Like the mulberry, it can also grow large; given decades and not much pruning, the pagoda tree can also reach 8m wide by high. ✤