Gardener’s
Corner – Wisteria: winding and wistful
But what has finally motivated me to
rest my bones and get typing was a Daily Mail article about wisteria, which the
newspaper claims can add 5% to the value of a property. If you can bear to read it (and an
entertainingly mixed comments section), here’s the link.
Without
doubt, wisteria does add drama, romance, and a wonderful “country cottage” look
to old and new properties alike. It melts hearts, fills the air with fragrance
and is a magnet for bees. However, as with all climbing plants, the amount of
effort increases with the height and volume of growth. A £40 investment (just)
might buy 2-3 weeks of bloom, but wisteria needs hand pruning at least twice a
year - which means several hours up a ladder. It is deciduous, so there will be
a bare, disorganised framework of silver-grey woody stems randomly covering a
sunny wall. And just how invasive is it?
Lacking any
gardening experience 26 years ago, I planted five wisteria shrubs against our long
south facing wall. Four have survived 26 years, narrowly avoiding destruction
by what appeared to be field mice nibbling the bark, which was eventually
countered with chicken wire wrapped around the main trunks. Currently there are
long racemes of scented pea-like flowers draping gently over the windows. It is
overwhelmingly lovely. Our 1870s brick-built home hasn’t been undermined by its
roots or overwhelmed by its rampant growth - mainly because of the effort taken
to manage it. So here is a quick checklist of ideas, tips and “learnings from
experience” to help make sense of the hype and/or help you decide whether
wisteria is for you – and if not, what else might make a suitable alternative.
There are three
types of wisteria readily available – Chinese, Japanese, the native US variety
Wisteria frutescens which is considered less vigorous- and several hybrids. All
wisterias flower in late Spring before producing foliage; they send out long,
untidy shoots of light green foliage and tendrils after flowering and throughout
the summer, until the cold weather causes the leaves to turn yellow and drop
off. The spectacular flowering is over within 3-4 weeks; the plant is then
smothered in foliage until autumn and the plant is then completely bare until
new flower buds form in early spring.
The long
racemes of flowers can form seed pods which drop during the colder months and (like
the plant itself) are toxic. Wisteria can take 15 years to begin flowering reliably;
a plant grown from seed is a long experiment as it may not come true to form,
and nurseries typically propagate by grafting to save time and ensure
consistency. A lot of wisteria is only limited in height and vigour by the
availability of support that they can find: the stems coil so tightly that they
will kill a living support (such as a small tree). They also continue to shoot
not only from the stem and upper framework (vertical stems), but also from the
base (lateral stems, which need removing before they take root). In summer,
their tendrils can become a nuisance near paths and doorways- a gust of wind
can easily create a whip-like smack of vine tendril across an unsuspecting
face!
Chinese and
American frutescens wisteria twines counter clockwise,
whereas Japanese wisteria twines clockwise. The bigger hybrids can grow 70-80-
feet and they require very strong support, usually strong wires fixed into
masonry/ solid wall. The stems only need attaching to the wires during the
first few years; thereafter they will interlace and thicken along and up the
wires towards the sunlight. Full sun is vital and a warm
wall optimises growth. All wisteria will produce a thicket of lush, top-heavy growth
if left unmanaged. So do think carefully about who will be responsible for
setting up a solid wire or trellis structure, pruning back twice yearly, and disposing
of prunings and leaf fall. An expert guide on growing
and pruning wisteria (with heavenly pictures!) can be found here.
Wisteria is
available in shades of purple, white and pink. Shades of purple offer the most
“classical” look; however, I have seen beautiful displays of white wisteria
work well against the right kind of brick, stonework
or painted surface. Many hybrids are bi-coloured (usually purple or pink
combined with white).
Given a
sunny spot, reasonable soil and strong support, wisteria is very easy to grow,
and it should not need fertilising or watering once established. Other than
mice sampling the stems, I have not known it attract any other pests or
diseases. But do watch out for bees – they love wisteria flowers and can linger
all day! As a member of the legume (pea) family, wisteria
creates its own fertile environment by fixing nitrogen in the soil - which
other plants can also take good advantage of. The roses, peonies and hibiscus
under my wisteria have never needed extra fertiliser, and they are good
companions to extend a colourful display right into the autumn.
Roots: the
root system will be as extensive as is necessary to support a rampant climber –
but a good wire/trellis structure is likely to check root growth by reducing
the extent of the root system needed to anchor the plant. There has been no
evidence of root damage to our 1870s home in the UK, but the paved patio alongside
the wisteria is prone to “lifting”, indicating that the root system extends
some way under it. In warm locations where wisteria is known to grow more
aggressively, it is wise to avoid planting within the vicinity of underground
pipes or major structures – perhaps use a pergola, trellis
or archway where the plants can romp well away from vulnerable areas. In the UK
the plant doesn’t distribute seeds in the same way that a shrub such as
buddleia might spread – however, the tendency to self-seed can be problematic
in other countries/ climates.
It is very
easy to grow wisteria in large containers – mindful that they will need
watering during the growing season. Despite this, there are several advantages
to consider:
a.
Containerised
wisteria works well in smaller spaces.
b.
Containing
the roots will act as a check on overall growth.
c.
After
the fabulous few weeks of flowering, the container can be swapped for a
different one offering summer interest (for example, a repeat flowering rose).
d.
A
containerised wisteria can therefore be treated as an annual display feature, possibly
eliminating the need for a permanent support structure fixed to a wall. A tall
wooden trellis can suffice as temporary support for a shorter variety.
e.
The
main stem of a containerised wisteria can trained around a wood/steel support to
create a “standard tree” which will naturally “weep” with fragrant blossom from
the top of a corkscrew-like trunk (remember to prune off the lower shoots).For those with deep pockets and no patience, it is
possible to buy specimens already half- or fully trained as standards.
f.
A
shorter, containerised shrub can be pruned back more easily (you may not even
need a stepladder!)
Given plenty
of sun and a little skill, a 6-8 foot standard
wisteria can also look stunning as a small feature tree. In larger gardens,
pergolas and arches can be expanded or linked to form breathtakingly beautiful
arbours, seating areas and tunnels. However, it is difficult to combine wisteria
with other climbing shrubs (such as roses or clematis) because of the untidy
growth habit and different pruning schedules. Instead, I grow tall shrub roses under
the wisteria to provide summer-long colour.
Varieties of
wisteria… I can only offer a guide based on what sells and works in the UK:
·
Best
for beautifully fragranced, frothy long racemes: Wisteria Sinensis (Chinese) or
Wisteria Floribunda (Japanese) varieties. These tend to be vigorous and more
suitable for large spaces. Available in purple, white and pale pink. Wisteria
Sinensis “prolific” is very free-flowering and one of the best for fragrance.
·
Best
for smaller walls, pergolas, arches and containers:
Wisteria Formosa hybrids grow up to 30 feet/ 9 metres and are more manageable.
Other suitable varieties include brachybotris
(“silky”) and valderi “lavender lace”.
·
Favourites
for containers and training into a standard tree are the Frutescens varieties
“amethyst falls” and “longwood purple,” which in the UK might top 5m but can be
maintained at a much smaller height.
Returning to
the Daily Mail article, the £40 investment quoted in the newspaper may
buy you a good, healthy specimen – but it may not be ready to flower for some years.
A 6’ grafted specimen ready to bloom next Spring is more likely to cost at
least double that sum. Well worth
checking how long you will have to wait before you buy it! And when you add on
the cost of installing strong wires and twice-yearly pruning (even if performed
yourself), the cost is not so cheap. Another consideration is that (like
swimming pools) one person’s love of wisteria is another home hunter’s
nightmare. Plant it for yourself, and not in the hope that it will boost the
value of your home. Personally, I love looking forward to the day it first
breaks bud, as a sign that the worst of winter is likely behind us.
What alternatives
are there to wisteria for a spectacular late Spring- early Summer
display? If you are wanting the classical “look” of a wisteria-smothered wall,
it is hard to think of an alternative that will bloom at the same time and in
the same way. The most obvious alternative is Laburnum, a similarly rampant
member of the pea family with acid yellow racemes of scented flowers that also
bloom during late Spring or early summer. As with wisteria, all parts of
laburnum are highly toxic to humans and animals (especially the seeds). It can
be used in the same ways as wisteria, but its acid-luminosity is far bolder compared
with the cool shades of wisteria.
For a less
rampant, better behaved early summer display, perhaps consider the deep
evergreen foliage and bright blue flowers of Ceanothus, which will not grow as
tall but is more manageable and it keeps its stunning foliage in winter. Or an
early-flowering rambling rose (the very reliable Veilchenblau
will give you a rich purple-blue display for 2-3 weeks on bright green, almost
thornless stems that can be wound around most structures). Repeat climbing
roses are better behaved than ramblers and come in many shades and sizes; they
bloom a few weeks later and will flower again intermittently until the first
frosts. Clematis also comes in many shapes, sizes and
colours; these are more delicate and can be useful on their own, or to provide
colour and scent woven through a rambling rose after it has bloomed.
If I have
whetted your appetite, here are some good online sources in the UK of wisteria and
other shrubs I’ve mentioned. Online nurseries often provide good information
and are terrific value if you can cope with waiting to get your hands on the
plants during busy periods. Otherwise, the advantage of visiting a garden
centre is that there will be professional advice on hand and instant
gratification when you buy something. Given all that I’ve mentioned about
growing from seed, do avoid buying an unnamed wisteria plant (especially if
very cheap) because it may not bloom or perform as you might expect.
Gardening Express has supplies of several varieties of
mature (6’) and smaller wisteria plants, as well as some unbeatable offers on
soft fruit, fruit trees and dozens of garden plants.
Crocus also has a good selection of wisteria plants in varying sizes depending
on your budget and patience.
Wishing you
happy gardening – whether it’s warming up or cooling down where you are!
Sian Lloyd
June 2023