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. ¼ 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 è 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.Redouté. 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 São 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 (24–30 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 (2–6 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 problems with thrips, and aphids. Stink bugs may cause bud drop
(W10). In the sub-tropical areas of Australia, scale and mealy bug may
be a pest.
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CARE
AND MAINTENANCE
No special care is required (W10). (Right
Photo: Close-up of staminal column of H. arnottianus - Geoff Keena © 2002).
PROPAGATION
Rooting terminal cuttings is recommended (W3) although either terminal
or stem cuttings can be rooted with rooting hormones under mist (W10). Hardwood
cuttings, pencil thickness, devoid of leaves, 12 - 16 cm (5 - 6 inches) long,
taken in spring and placed in coarse river sand and peat, strike readily (P3).
As the plant sets seed readily, it may be grown from seed sown in the spring
(P3). However, seedlings may not be true to type (W10). Seedlings are slow-growing
(W3).
Hibiscus arnottianus also can be propagated by air-layering
or grafting onto other Hibiscus species (W3; W10).
PART 3
HYBRIDISING
As
was noted in the introduction, there was an article on hybridising hibiscus in
the first issue of Hibiscus International. The author wrote that although hibiscus
hybridising was tried at earlier times and in other places, Hawai'i was in fact
the place where any large scale hybridizing took place, and the first recording
of this was in the mid 1800s. She continued that large scale interest took off
around the turn of the century, and by 1911 there was a Hawaiian Hibiscus Society,
with several thousand hybrids displayed at the first show. Native Hawaiian hibiscus
such as H. kokio (koki'o 'ula'ula) and several varieties of native Hawaiian
whites (Koki'o ke'oke'o) were often used as parents, crossing with plants introduced
from other places (W5).
Many
variants of Hibiscus arnottianus have been or are in cultivation, and some
have been hybridized with Hibiscus rosa-sinensis (Wilcox & Holt, 1913;
Bates, 1965 in W9).
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In relation to the varieties of native Hawaiian white
hibiscus, hybridising records can be confusing. Early records may have used common
names, e.g. 'Ornamental Hibiscus in Hawaii' of 1913, (W11). This reference states
that Hibiscus arnottianus is a native white species which occurs under
several quite distinct forms, at least from the horticulturists standpoint. These
forms are commonly called Tantalus White, Waianae White, Punaluu White and Nuua-nu
White.
The text notes that Hibiscus
waimeae*(W11) is also a native species with pure white flowers, and occurs
under at least three forms, referred to as Knudsen White, Rice White and Lydgate
White. It continues that Molokai White is apparently an undescribed species. There
is also a description of a cross between Knudsen White and Punaluu White, that
is, is a cross between Hibiscus waimeae and Hibiscus arnottianus.
Crosses between the two native white species are a further complication.
Another source of confusion, such as in the International
HIBISCUS rosa-sinensis Register and Checklist (W12), arises from the fact
that not only might common names, rather than botanical names have been used in
the records, but subspecies may not be shown. Common names include Punaluu White,
Nuuanu White and Tantalus White. Botanical names are given as Hibiscus arnottianus,
Hibiscus immaculatus and Hibiscus punaluuensis.
In the Hibiscus Register (W12), common names given in
the records include Tantalus White (Albo Lacinatus), Punaluu White (Ross Estey),
Waianae White (Annie Hobron). Botanical names include Hibiscus arnottianus
(Agnes Galt), Hibiscus immaculatus (Mrs James E. Hendry) and Hibiscus
punaluuen-sis (numbered seedling).
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Crosses
in the Bulletin (W11) and in the Hibiscus Register (W12) where Hibiscus arnottianus
was a parent, indicate that seedlings range in colour from nearly white, to pale
pink, light crimson pink, to pink suffused with apricot to yellow.
Hibiscus
arnottianus has a number of features of interest to hybridisers.
Firstly, it sets seed readily (P3). It is interesting that most of the
crosses shown in the Hibiscus Register list Hibiscus arnottianus
as the pod parent (W12). The exception to this is Punaluu White which
is shown as the pollen parent of five crosses, including Ross Estey
(W12). Secondly, the blooms last two days. The third feature is that
the flowers have an exquisite fragrance (P3). This characteristic is
pos-sibly of most interest to current hybridizing prog-rammes.
One
of the people involved in using Hibiscus arnottianus in a planned hybridizing
programme is Brian Kerr who lives in southeast Queensland, Australia. The gardening
conditions where Brian lives are described as sub-tropical.
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PART 4
Hibiscus arnottianus is described as having flowers which are weakly fragrant (W9) whereas the flowers of Hibiscus waimeae are described as strongly fragrant (W9). Hibiscus waimeae can be divided into 2 subspecies: subsp. hannerae and subsp. waimeae (W9).
I
have most interest in Hibiscus waimeae, especially Hibiscus waimeae
subsp. hannerae as I have read about the 'pervading odour' of Hibiscus
waimeae. For now I will work with Hibiscus arnotiannus.
I agree that there is much confusion. What
is a true Hibiscus arnotiannus? What we have in southeast Queensland as
Hibiscus arnotiannus may be a hybrid between some of the native Hawaian
types. Hibiscus arnottianus as I know it just does not match with the descriptions
I have read of this species or its subspecies.
My
experiences so far are that Hibiscus arnottianus (hereinafter referred
to as "A") is well suited to growing in full sun, enjoys a yearly prune and will
remain a dense shrub with this treatment. Its growth speed is quite good. For
grafting purposes, it can be used as understock and itself has taken on Albo Lacinatus
(hereinafter referred to as "AL"), Landersii and some of my discarded seedlings.
Cuttings will root easily, but are slow to get going at my place.
The blooming capacity of Hibiscus arnottianus
is amazing, with hundreds of blooms on a 1.5m bush. It does not seem to need a
great deal of attention and can grow well in a variety of soils, the best results
coming from sandy soils, high in mineral matter. Blooms last one day only in hot
weather and two days in the cooler weather. The hibiscus beetle loves this white-coloured
bloom of course. It is not resistant to Erinose mite.
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Hibiscus
arnottianus does not self seed readily under Sunshine Coast conditions, though
I do get the occasional small pod resulting in one or two seeds only. It will
set seed readily when hand pollinated and produces large, full pods averaging
perhaps a dozen seeds. The highest number of seeds were achieved when using Hibiscus
schizopetalus (hereinafter referred to as "S").
I have used Hibiscus
arnottianus with a variety of today's coloured blooms to give myself a varied
base of colours to use in future breeding. The main aim here is to put the blooming
capacity and self rooting ability of Hibiscus arnottianus into new cultivars
resulting from this cross. I think it is a good idea to cross back to older varieties
every few generations.
My interest in inter-crossing the older varieties
and species started as one of general interest, but is now a search for knowledge,
a search to try and find, prove and confirm the parentage of some of the older
varieties and to produce a frilly edged, mini white. Perfume would be a bonus.
Also, by back-crossing with modern day blooms in a variety of colours and then
inter-crossing these, to try and produce some frilly edged, yellows, purples,
browns and multi-colours on attractive, perhaps caney, bushes. Hibiscus arnottianus
does fit in to this programme with its contribution as the best bloomer, white
colour and perfumed background. As far as perfume is concerned, I cannot detect
much odour from Hibiscus arnottianus. The only perfumed hibiscus at my
place is my Hibiscus arnottianus (A) X Albo Lacinatus (AL) seedling.
The
following are the crosses so far using the following pollen parents:
1. A x (Purple Robe
x Hibiscus schizopetalus)
2. A x (Shirley Howie x Alex Pimm
-1)
3. A x (Shirley Howie x Alex Pimm -2)
4. A x Leopard
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5. A (x) AL: has produced very tall A look-a-likes in all but one. This was the slightly, frilly-edged mini with a flowery perfume that I posted to the IHS List.
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6.
A (x) S: with all blooms being
near exact replicas of AL in habit and bloom colour. The most interesting of these
is one with speckles evident, like you see in Patricia Noble (Sport of Ross Estey
- this having A in its background). These speckles are not unlike Ali Uii speckles
in some way, though not as 'standoutish' as they are on a pale bloom and not as
wide-spread. Leaf colour, shape and bush habit is noticeably different to me,
but not to other observers. It appears that these speckles do not come through
in photography.
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7.
A (x) Cuban Variety (CV): A deliberate cross to try
to produce the ultimate bloomer in any colour that resulted, with maybe perfume
as an afterthought; also to get a compact bush, as both produce compact bushes
in my crosses so far.
8. A
(x) (Cuban Variety x Albo Lacinatus) (CVAL-1): A deliberate cross to try
and resurface the blooming capacity of A and the amazing blooming capacity of
CV in any colour that resulted, with maybe perfume as an afterthought; also to
get a compact bush. The result of this cross will be put to A (x) AL above, the
white, mini, slightly perfumed, fringed single.
9. A
(x) Herm Geller (HG): A x HG has not bloomed, but the bush needs
men-tioning as it is so well formed. However, the leaf seems to suffer
from a brown fungal type infection in winter on the top of the leaf.
Initially the marks look appealing, but eventually the leaf dries and
falls off, leaving a stark, unattractive bush.
10. A (x) Nasali Pink
(NP): crossed these as NP (Right photo: Jim Purdie ©
2002) is a great bloomer - to produce one with excellent blooming capacity
and to get a compact bush., as both produce compact bushes in my crosses so far.
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All others are progressing in varying ways and if they survive the red spider and cold and wet (and a batch of bad, heavy potting mix), will hopefully bloom in the next year.
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REFERENCES: (Printed Material)
2. Howie, J. (1980) Hibiscus Queen of the flowers.
First Edition, Prestige Litho Printing Co., Australia.
3. Beers, L. and Howie, J. (1985) Growing Hibiscus, Kangaroo Press Australia.
4. Gast, R. Chapter 2 in The Genetic History of Hibiscus rosa-sinensis in
Beers,
L. and Howie, J. (1985) Growing Hibiscus,
Kangaroo Press Australia.
REFERENCES: (Web Links - as of 30 June 2003)
2. http://www.botany.hawaii.edu/faculty/carr/hibiscus.htm
3. http://www.hawaii.gov/health/oeqc/garden/eioegkeo.htm
4. http://www.internationalhibiscussociety.org/hiv1n1.htm#_Hybridizing_
In_Hawaii_3
6. http://www.tropical-seeds.com/tech_forum/flowers_orns/oahu_wt_hibiscus.pdf
7. https://ecos.fws.gov/species_profile/SpeciesProfile?spcode=Q2BC
8. http://starbulletin.com/2003/01/03/features/garden.html
9. http://www.hibiscus.org.au/part2.htm
10. http://www.tropical-seeds.com/tech_forum/flowers_orns/oahu_wt_hibiscus.pdf
11. http://www.hibiscus.org.au/hawaiian.htm
12. International HIBISCUS rosa-sinensis Register
and Checklist, 2002 (CD) ICRA (Hibiscus) Register/ChecklistWeb: http://www.geocities.com/auhibsoc/ira/register.htm
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Board of Directors
President: Jim Purdie –
Past President: Richard Johnson – Tamanu,
Vice-President: Carlos C. Quirino, Jr. – Metro
Secretary/Treasurer: Richard Mansbridge –
American Rep: Robert Cook –
Australian Rep: Graham Boytell –
European Rep: Jean-Francois Giraud –
Asian Rep: Carlos C. Quirino Jr.
Pacific Rep: Richard Johnson
Webmaster: Joseph
Dimino –
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Rights Reserved © 2003
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