By: Jim Purdie
I would like discuss the subject of
pruning your plants. The ideal time to be thinking about carrying out this exercise
is in the Spring which coincides with your plants beginning to start sending out
new growth as the weather starts to warm up after the cold winter months.
This
is brought about by a few things the most important being that daylight hours
begin to get longer as the sun on its journey begins to get closer to your country
where you live, be it in the northern or southern regions of the world.
Also,
as it gets closer, the weather begins to warm up and this causes the sap to flow
and in so doing it causes the roots to start to draw more nourishment from the
soil. This causes the plant to go into a growing mode with new shoots beginning
to appear at the eyes on the mostly bare sticks we have seen during the winter.
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Always make sure, if you live in areas where you experience frosts, not to do your pruning until the danger of frosts have passed as frost will burn off the tender new shoots.
We prune our plants for a variety of reasons. I will list the most important reasons that we have to prune for:
1. To train a plant or bush into a
desired shape.
Whenever
I start to prune I try to think how the bush grows and prune the plant according
to the way it grows. By that I mean if the plant is an average grower, I will
prune off about a third of the bush. If the bush is a tall fast grower I will
prune off about a
half and if the
plant is a slow low grower I will only just prune
the tips otherwise it takes too long to recover if you give it a hard prune and
you will miss out on the flowers for that season and have to wait until next year
to see some blooms.
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I prune just above an outward pointing
eye, using a slanting cut away from the eye, so any water will run away from the
eye, and also it encourages the new shoot to grow outwards instead into the middle
of the plant, and I always try to end up with a pruned bush, which is in the shape
of a vase. Make sure your secateurs are kept clean and sharp, so they will give
a clean cut, and I like to dip my secateurs in some alcohol or methylated spirits
between bushes to prevent spreading any disease.
Some members do not prune all the branches
at one time so they are able to still have blooms while they wait for the new
growth to flower. These remain-ing branches can be pruned once the new growth
commences flowering.
If you are growing in pots this is a good time to think about doing a root prune at the same time as you prune the top of the plant, and repot into some fresh potting mix, with some slow release fertilizer included in the mix, either into the same size pot if it is the biggest you want to go to, or the next size pot if it is in a smaller pot.
When the bush is putting out a lot of new growth this is the time when I apply fertilizer high in nitrogen to promote new growth and apply this until you see new buds starting to form and then I start to use a fertilizer higher in potash than nitrogen to promote flowers instead of nice green leaves.
The fertilizer mix I use after pruning, for the plants I have in the ground, is one that I mix myself, and is as follows:
b.
2
of Super Phosphate;
c.
1
of Sulphate of Potash;
d.
½
of Magnesium Sulphate or Epsom Salts; and,
e. Ό of Sulphate
of Iron.
mix all this well together and apply
a good handful around each bush. Then I cover this with a good cover, about 2
to 3 inches, of a suitable mulch. This will keep the roots cool in the hot weather
to come.
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Digital
Collage By: Carlos C. Quirino, Jr.
Photo of Cheo: Jim Purdie © 2003
A "good bush" means different things
to different people. In Europe it is basically a compact, natural branched
plant which when pruned responds with several new branches. 
In the US and 0z, it needn't necessary
be that compact, is considered generally acceptable if it forms a nice
bush with proper pruning; hence, needn't necessarily be a good natural
brancher and two branches per pruned stem is I think think considered
OK. Now both of these "good bushes" are generated by slightly different
needs based on climate, growing condi-tions, etc. However, it has occurred
to me that in the past the interpretation of a "good bush" is too narrow.
For example, I can envision special purpose bushes such as hanging baskets,
the patio, etc. in which case neither of the above "good bushes" would
be ideal on a patio. I could well envision a plant which cascades over
the side of the pot making a mound of greenery with blooms. If one can
develop a similar type bush of small enough size, it might be adaptable
as a hanging basket plant.
My point is that I think it is worth considering hybrids with growth habits
that do not fit the classic garden variety profile. For that reason I'm saving
a few of those Miss Liberty seedlings that have inherited what is considered the
worst of Miss Liberty qualities, i.e., a bush that has curling or spiraling branches
that fall over the edge of the pot.
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You
won't want such a plant in your garden, but might find it very attractive on the
patio, around the pool, on a terrace or in an apartment where you want low profile
color.
This brings to mind another aspect of a cv bush type. Miss Liberty, again
as an example, is a notorious floppy bush, but if you grow it like Allan
Little does (Photo, left inset: 
Persephone Standard Bush: Allan Little © 2002),
it is respectable and compares favorably to the typical "good bush" form,
although still perhaps not ideal.
What I'm getting at is that a cultivar may or
may not have a typical growth habit and in many cases, it varies from one bush
of the same cv to another. I have several cultivars for which I have double and
triples of the same plant, essentially all grown and pruned similarly, yet I find
different growth habits.
Red
Snapper for instance has two growth forms for me: 1) an open rigid bush
with lateral somewhat twisted branches with pom-poms of leaves at the
end and, 2) one with vertical growing better foliated branches, which
needs support. Same cultivar, two different appearances.
Now if I were trialing this cv and only had one
plant, I might come up with two entirely different opinions of its growth habits.
Another example, as I mentioned recently, I have a heavily pruned Rum Runner both
because of the demand for wood and because it was growing into an awkward bush
with lateral branches. Now, I can hardly imagine a HOTY candidate of the stature
of Rum Runner having been considered for a HOTY award if it had the growth habits
of mine. (Right top photo: Gabriela bushed in pots: C. Quirino
© 2002).
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I
also have several others with duplicate plants - Improved Crimson Ray, Dragon's
Breath, Fantasy Charm, High Voltage, to name but a few, and in every case one
particular plant for a given cultivar will have a notably nicer classic bush type"
than the others of the same cultivar, which all goes to point out that there is
some variability, even significant variability, in bush type for a given cultivar.
We've had occasion to talk about this before,
i.e., Black Knight and Eva Paoloni - which are for most people not ideal
bushes, but for others are quite acceptable. I know, when we talk about
the bush type of a given cultivar, we are talking about averages, but
the above will perhaps serve as food for thought concerning the subject
of hybrid-izing and the significance of bush type (Photo,
left inset: Mellie May bush from Greg Lindsay: R.Johnson © 2002).
I suspect that if we
would get the opinions of beginning hibiscus growers, especially those that grow
in pots and in confined spaces, e.g., an apartment, their ideal bush type may
not be that which is generally considered best and based on the typical garden
variety profile, i.e., as an in-ground plant for the garden.
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SPECIES AND HYBRIDS
By: Colleen Keena,
The
species of hibiscus that occur in Australia range from plants found only in Australia,
such as Hibiscus splendens, H. divaricatus and H. heterophyllus,
to plants with a widespread distribution, e.g. Hibiscus diversifolius and
Hibiscus tiliaceus, now Talipariti tiliaceum. H. trionum
has forms such as var vesicarius that occur only in Australia. Plants can be small
like H. trionum and H. sturtii, through to large shrubs such as
H. heterophyllus, H. divaricatus and H. splendens. Many are
useful plants. The petals of Hibiscus heterophyllus, or of crosses from
it, can be made into a delicious jam, cordial or syrup. Seeds of Hibiscus heterophyllus
were collected on the Baudin expedition of 1800 and grown by Empress Josephine
at Malmaison. The botanist Aim θ Bonland wrote of its medicinal qualities, noting
that it tasted like sorrel and could be grown in a vegetable garden. It was painted
for the Empress Josephine by P.J.Redoutι. This botantical painting can be seen
in Napoleon, the Empress and the Artist by Jill, Duchess of Hamilton.
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Hibiscus insularis
 H. trionum var vesicarius |
 H. sturtii |
(All Photos In Photo
Gallery:
Colleen Keena © 2002)
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This
article has been compiled by Colleen Keena from Queensland, Australia, Kristin
Yanker-Hansen from California, USA and Marcos Capelini from Sγo Paulo, Brazil
and is part of the Marvellous Mallows series.
PART 1
INTRODUCTION
Many
times in novels or in films the hibiscus flower is referred to as fragrant. Yet
in reality very few have that trait, except for the white hibiscus species from
Hawaii.
Hawaii has a number of species of the Hibiscus family.
Although some of these also occur in other countries and may have been introduced
to Hawaii (P1;W1), there are a number of species of hibiscus which are endemic
to Hawaii (W2).
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One of the species
endemic to Hawaii is Hibiscus arnottianus.
It is noted for its
fragrance (W3). It is described as a spectacular shrub during its flowering
season with its large, white flowers. While the frag-rance and beauty
of Hibis-cus arnottianus are impor-tant features, it is often
used by horticulturists to hybridise with Hibiscus rosa-sinensis (W4)[H.
arnottianus Bush In
Therefore,
while Hibis-cus arnottianus is a beauti-ful plant in its own right,
with fragrance and spec-tacular flowering,its com-patibility with Hibiscus rosa-sinensis is a feature that has not only been
of interest to early hybridisers but continues to attract those interested
in developing new forms of hibiscus. This interest in hybridising was
reflected in the very first issue of Hibiscus International by Jill
Coryell (W5) and will be discussed in Part 4 of this article.
THE SPECIES
Hibiscus
arnottianus is an evergreen multi-trunked shrub or small tree, growing to
8 - 10 m (2430 ft) high, with a dense crown of foliage and smooth trunk and branches.
The leathery, dark green, ovate leaves are entire (with smooth margins) and are
5 15 cm (26 inches) long. The leaf veins and stems commonly are red. The tubular,
slightly fragrant, solitary flowers, measuring up to 4 inches across, are white
with pinkish veins or pure white with red filaments and a magenta staminal column.
The papery fruiting capsule is about 2.5 cm (1 inch). It contains seeds covered
with fine yellowish-brown hairs (tomentose)
(Upper right photo: H. Arnottianus
Bush in
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subsp.
Arnottianus
has smooth young stems, leaves, pedicels, and calyces;
native to Oahu (Wahiawa to Niu Valley).
subsp. Immaculatus has unusually deeply crenate leaves and a white staminal column; native to Molokai (Wailau, Waihanau. and Papalaua valleys).
subsp. Punaluuensis a robust form with moderately coarse pubescence on young stems, leaves, pedicels, and calyces; native to Oahu (Kaipapau to Waiahole).
Cultivars have been selected by the Harold L. Lyon Arboretum: 'Kanani Kea' a selection with large flowers and good form. 'Shy Girl'-flowers with a pink blush on the back of the petals and edges (W6).
One of the subspecies, Hibiscus arnottianus subsp. immaculatus was design-nated as endangered in 1992 (W7).
The flower buds of Hibiscus arnottianus subsp. immaculatus were eaten, or are eaten still, by Hawaiians as a gentle laxative. Cordage was also made from the stripped bark (W8). A more detailed description of the species and subspecies is available (W9).
PART 2
CULTURE
INTRODUCTION
Hibiscus arnottianus is now grown well beyond Hawaii. For example, it is
grown in areas as far apart as California and Queensland, Australia, and in a
range of conditions. Any consideration of culture needs to take into account the
environment in which Hibiscus arnottianus occurs. Hibiscus arnottianus
is found in dry to wet forest areas at 300 m - 800 m (1000-2500 ft) elevation.
It grows best under filtered shade in moist, well drained soils, but it will tolerate
full sun (W10). Although this plant will thrive in partially shaded areas, for
at least the subspecies immaculatus, it will bloom more in full sun (W8)
(Left photo: Colleen Keena © 2002).
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CULTIVATION
Although in its original location Hibiscus arnottianus grows best under
filtered shade, references on cultivation recommend a full sun position (W:10)
with the ideal being an open sunny situation (P3).
Experience
with growing it in California and Queensland sug-gests that established
plants can recover from light frosts (-4C/25 F) but if planting it in
an area where frosts are likely, growing in a pot so it can be sheltered
in winter is recommended.
As already noted, Hibiscus arnottianus occurs in well drained soils.
References relating to cul-tivation indicate that it grows best in rich sandy
soil (P3) or an organically rich, well drained soil (W8) (Upper
right photo: Richard Johnson © 2002). Although it will ultimately become
a small to medium size tree, it is a slow grower and will remain a shrub for many
years (W3). It is long-lived, hardy and resistant to root-rot and borer (P3).
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WATER
REQUIREMENTS
Although occurring naturally where there are moist well-drained soils,
Hibiscus arnottianus will tolerate dry con-ditions (W10). Its
water requirements are described as moderate (W3) although liberal water
and fertiliser should be ap-plied during the flowering season, which
is summer and autumn (P3).
LANDSCAPE USES
Hibiscus arnottianus may be used as a single specimen plant,
in groups for mass plantings, or as a screen or hedge plant. Its medium-textured
foliage and flowers make it attractive for landscape uses (W10). It
can also be planted as an accent in front of dark backgrounds such as
a rock wall to show off its beautiful white flowers (W8). It can be
grown as a large container plant (W10). When grown in a container, it
can be positioned to enjoy the fragrance (Upper left
photo, in Tahiti: Richard Johnson © 2002.
PRUNING
The two-day blooms are produced freely on short spurs from older wood
and so it is best left unpruned. However, a severe pruning, about halfway,
in spring every four to five years is recommended to keep the plant
healthy and in a good shape (P3).
PESTS
It has no significant insect pests or diseases although Chinese rose
beetles and white flies may cause minor damage (W3). There may also
be some pro