Yuccas not Yukkies
If you like your plants spiky and architectural,
this is for you.
Angus White, Architectural Plants, Cooks Farm, Nuthurst, Sussex
Chamaerops No. 7, published online 23-10-2002
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Left: Yucca recurva - or is that recurvifolia?
Right: Small but beautifully formed - Yucca whipplei.
Some people don't like Yuccas. They think they are
nasty spiky things and call them "yukkies". They think
this is terribly funny and rather clever which, of course, it isn't.
These people are hopelessly deluded and the only reason they feel
like this is because they're boring and stupid. The people, that
is, not the Yuccas.
That's the nice thing about writing for a magazine
like this; you know you're preaching to the converted and can really
get your rocks off.
Having said all that, it's quite true of course
- they are nasty spilcy things. Some of them are vicious in the
extreme, but, they're also - at least some of them are - beautiful
dramatic, exotic and bold. They didn't get their common names such
as "Spanish Dagger" and "Bayonet Plant" for
nothing you know.
They all come from the New World, most from the
southwestern United States, some from the southeastern and central
United States and some from Mexico and Central America. The best-known
and hardiest ones grown in the British Isles come exclusively from
the United States. They all look spiky to a greater or lesser extent
and they all send out tall flower spikes covered in masses of almost
spherical flowers between pure white and cream. An essential point
to grasp right at the beginning of the road to Yucca-enlightenment
is the two broad groups into which the Yuccas fall:
1. The Clump Formers. These consist of many separate
plants within a clump. When an individual flowers it subsequently
dies but is replaced by more shoots, so the clump is preserved.
The individual plants never form what could be described as a trunk.
2. The Trunk Formers. Botanically described as arborescent,
these form trunks on which the rosette of spiky leaves always appears
to sit. When they flower, instead of dying, they branch. Flowering
can result in two, three, four, or even five new shoots being created.
Each shoot then goes on to create its own trunk - or what one would
normally refer to as a branch.
Intelligent Cultivation
Yuccas are and have been for some time, grown quite
widely in Britain. The common perception of their desirability seems
to be largely based on their dramatic flowers rather than the wonderful
architecture of the plant itself. Therefore, little thought seems
to go into the subject of how the plant actually looks for the 49
weeks of the year when it's not flowering. As with so many plants,
it's a simple matter of standing back, looking at your plant and
asking yourself whether it really looks the way you want it to and
if it doesn't, what are you going to do about it.
Trim & Feed
Remove old, dead and tatty leaves and dead flower
spikes and get the plants to grow vigorously by plenty of feeding
(springing 'Blood, Fish and Bone' round the plant in the spring
is very effective). You might have to remove branches that have
formed following flowering in order to create a single trunk, remove
suckers to encourage healthy top growth or just remove the brown
bits. It only requires common sense and a little imagination.
Once one gets into this more 'manipulative' attitude
towards growing things - a whole new world opens up. It's so easy
and yet it's so rarely done; people don't do it because other people
don't do it and they apparently think that other people don't do
it for a reason. What reason? I don't know - maybe they've just
never thought about it.
Thoughtful Approach
At our nursery we spend much time going on about
this more 'thoughtful' approach to growing plants. Healthy plants
grow more vigorously, have more new growth on them and therefore
look better. Remove the brown bits, avoid trying to grow inappropriate
plants in inappropriate places (Trachycarpus palms on the front
at Shanklin?) and use your secateurs in a creative and thoughtful
way. What could be simpler? Despite this apparent simplicity, Japan
is the only country where such an approach is part of their horticultural
tradition; they have a great emphasis on evergreens, non-flowering
plants and their sculptural qualities. In Europe the emphasis is
so often on flowers and little else; thoughtful cultivation extends
little further than topiary and the pruning of fruit trees.
It could be the mystique that surrounds the correct
pruning of fruit trees, rose bushes and other flowering shrubs that
inhibits the creative use of secateurs. People actually seem frightened
to use them. "But will it be all right?" is a frequent
rejoinder to the suggestion that someone cuts off the old flower
spikes and dead leaves on a Yucca. Yes, is the answer, it will be
all right. As with any idea that people are not familiar with, the
vocabulary surrounding it is an important tool for getting the idea
across. One has to experiment before coming up with the necessary
'catch phrase'. It is 'manipulative' but I must confess to finding
that word has too many unpleasant associations to be a useful adjective
in this case. I quite like 'thoughtful', because that is exactly
what it is...any suggestions? Maybe there's an expression in Japanese
that could be translated. Intelligent cultivation?
Brown Bitting
As the plant gets older, the old leaves die, hanging
down on to the slowly forming trunk (unless it's a Clump Former
in which case they lie on the ground looking grim) - just like a
palm tree. For aesthetic reasons already mentioned, these dead leaves
need removing. The contentious issue here is whether to pull them
off or to cut them off as near to the base as possible. For a nice
clean trunk, pulling the old leaves off is essential. BUT, if this
removal goes too far up towards the new leaves, the dreaded rot
can be introduced. Once the trunk of a Yucca gets rot into it you
must snap into action as soon as the ghastly discovery is made (bad
smells and black soggy bits). Surgical removal of the offending
area with a sharp knife followed by liberal applications of a powdered
fungicide (Benlate, for example) rubbed in well with the finger
is a sure remedy.
Sun Or Shade?
More contentiousness. If it's thought that the most
attractive aspect of growing Yuccas is their spectacular flower,
then a position in full sun is essential. BUT, is the most attractive
aspect of growing Yuccas their spectacular flowers? With the clump
forming species like Y. flaccida or Y. filamentosa then the answer
is probably 'yes'. Any other redeeming features they might have
are not immediately obvious - so why not enjoy the flowers? Some
of the trunk-forming Yuccas consist of a single rosette of leaves
that have a beautiful symmetry. Once a plant like that has flowered,
new shoots will emerge from amongst the head of leaves and the symmetry
will be lost. Having cast doubt on the desirability of the larger
Yuccas flowering, we need to investigate ways of discouraging them
from flowering. So far, there's only one way we know, and that's
growing them in the shade.
Some Of The Hardy Yuccas
Yucca aloifolia: One of the most distinctive
of all. We have a specimen that was dug up from a Chelsea garden
because it was "just too big". It had reached 12 feet
in about 15 years. This is unusual and reflects the warm microclimate
found in Central London, but even in rural Sussex we have specimens
of 4 or 5 feet that survived a low of -17c in February 1991. Despite
this they are not as hardy as some Yuccas and need careful positioning
in warm spots with perfect drainage. They only flower very reluctantly
so measures to stop them flowering and branching are quite unnecessary
plus they wouldn't do well in the shade anyway. They have leaves
that persist for a long time, sticking horizontally out from the
trunk, which usually has a diameter of some 4-5 inches. The leaves
have the most vicious points of probably all the Yuccas and yet
the profile of a well-grown plant is quite soft - I always think
of it as the prettiest of the Yuccas, despite its horrible armament.
There is a variegated version, which is occasionally available.
Smaller and slower growing but just as dangerous. It's very beautiful
but rather more frost tender.
Yucca recurva or recurvifolia: Look it up
in your plant book and it'll rather unhelpfully tell you that this
plant has recurved leaves; an expression I had a lot of trouble
with (i.e. I didn't know what it meant) until I realised it meant
bent. So the leaves go up when they leave the plant and then half
way up they bend and go downwards. The newly emerging leaves don't
bend, they go straight up, it's the older leaves that recurve. A
well-grown and vigorous specimen on a single trunk is a fine sight;
elegant, exciting and very frost hardy. This plant is considerably
m ore prone to flowering that Y. aloifolia and so a suitable candidate
for the shade. Some of the most magnificent specimens I've ever
seen anywhere are in the Cornish Gardens - whether in the sun or
shade, but only because they seem to grow such huge heads of leaves.
I'm sure this is a function of their reluctance to flower probably
due to the cooler summers encountered in that part of the world.
In the southeast, with its warmer summers, growing in shade is probably
the only way to inhibit flowering.
Yucca 'Vitoria Emmanuel II': A magnificent
monster of a plant, a hybrid, (originally bred by Carl Sprenger
in his nursery in Naples in the I 870s), between the two previous
species - Y. aloifolia and Y. recurva. This one is worth growing
for the flowers; it combines the frequency of the flowering of Y.
recurva with the hugeness and brilliant whiteness of the Y. aloifolia
parent.
Yucca gloriosa: The classic Yucca beloved
by Victorian gardeners with its thick trunk and stiff straight or
incurved (opposite to recurved?) leaves. Despite being so well known
a difficult plant to acquire. Like so many plants, the more you
get to know about it, the more confused you get. There seem to be
so many forms, I sometimes wonder if I've ever seen two the same.
By far the most spectacular plants I've seen, are multi-branched
but on a single and very stout trunk of some 3-4 feet. So the plant
couldn't have flowered for the first 5 to 10 years of its life.
Why? Possibly because they are grown from seed. Seed of Yucca gloriosa
is unobtainable in our experience because the flowers can only be
pollinated by the Yucca Moth, which only exists in certain parts
of the United States, and even if viable seed was formed, what form
of Y. gloriosa would you get? Normally, this plant can only be propagated
by division or rooting occasional offsets. As with any vegetative
form of propagation, this means that the new plants will think they
are mature and ready for flowering - and one is back to this problem
of preventing them flowering at an early age. Interesting isn't
it? The variegated version of this plant is produced by micropropagation
and is therefore fairly widely available. As with all variegated
plants, smaller and less hardy than the type, but still reliably
hardy in most of Britain and a splendid looking plant.
Yucca X floribunda: This plant is widely
sold as Yucca gloriosa throughout Europe, but it isn't. We are now
quite sure of the identity of this plant, a hybrid between the clump
forming and very free-flowering Y. flaccida and good old Y. recurva.
Plant this in a sunny spot and disaster will ensue. It almost flowers
itself to death. Yes, it flowers like mad, but the Y. flaccida parent
says "you have flowered so you will die if you don't send up
new shoots from the ground", so a forest of floppy leaves emerges
from around the original plant and the Y. recurva parent says, "you
have flowered, so you must branch". The result is a most unholy
mess of leaves and exhausted branches, usually resulting in the
eventual demise of the original trunk. This is the plant for shade
- even dense shade, where flowering is most unlikely and a single
trunk with a lovely rosette of leaves will be the result. Immensely
frost-hardy, this is the sort of plant to use where something like
a Cordyline australis wouldn't be sufficiently hardy.
Yucca glauca: Lots of very straight narrowish
bluish leaves, forms a small trunk, rarely flowers but doesn't die
if it does. Understand? So hardy that it would probably thrive on
Baffin Island, this is a landscape plant that needs to be used in
relatively large number to create a really good effect. In a good
rich soil, this could reach 4 feet across and 3 feet high. Removal
of the old leaves (Brown Bits) and prolific planting is about the
extent of Intelligent Cultivation that can be used on this plant.
Yucca whipplei: When small, this can be confused
with Y. glauca. A clump former with long thin bluish leaves, very
sharp at the ends. Eventually grows anything up to 8 feet across
with a massive flower spike up to 15 feet tall. This plant has a
wide geographical range between the Californian Coast, Arizona and
Mexico and the usual confusing array of different forms and different
degrees of frost hardiness. This will account for the apparent confusion
of accounts as to where you may or may not grow it in the British
Isles. Undoubtedly a very impressive plant but a very slow grower
in its first few years.
Some other impressive looking Yuccas that need further
investigation: Yucca rostrata, Y. schottii, Y. thompsoniana and
Y. treculeana.
Finally; many of the books mentioned in bibliographies
on this subject are out of print and hard to come by, but, the ten
page entry on Yuccas in my Bible, W J Bean's "Trees and Shrubs
Hardy in the British Isles", is essential reading with many
delightful quotes and purple passages.
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