14.
Questions and Answers
An easy way to diagnose your problems!
We have endeavoured to supply answers to the questions most asked about
hibiscus that we receive each year. Some specific problems cannot be solved
without inspection of the plant, whilst others are readily rectified.
Learn to observe your
plants - accurate descriptions of problems assist in recommending treatment,
many symptoms being similar but requiring different treatment. We sincerely
hope that our answers lead to better hibiscus!
Pests and
Diseases
Q. My plants are not flowering.
Although they look very healthy, there is no sign of any buds!
A. Hibiscus require full sun to
produce
good flowering wood, so the plant
could be growing in a shady position, otherwise the plant has been infested
with tip‑borer. This very small borer attacks the growing tips in spring,
automatically tip‑pruning the plant. The loss of the growing tip at this
time prevents the green wood in maturing into flowering wood. Spray regularly
during spring with Endosulfan or Carbaryl.
Q. Although I have been keeping it
moist, my plant is wilting.
A. Sounds as though you may have kept
it too moist, and it is suffering from either root‑rot or collar‑rot.
It is best to discard the plant and improve the drainage in that position, and
replace the soil before replanting.
Q. My plant suddenly turned yellow and
lost all its leaves.
A. This plant has received a severe
shock possibly caused by spraying with either Malathion or Lannate or other
systemic insecticide. Spraying on a very hot day, using too much white oil,
overfertilising or not watering the fertiliser in properly after application
are possible causes. Cultivating too close to the main stem, borer infestation
or collar‑rot may also be to blame.
Q. One large branch on my plant has
suddenly died.
A. Your plant has borer. Cut out the
affected parts immediately, and next pruning time, cut the plant back very hard
and drench the stems with either Chlordane or Dieldrin.
Q.
How do I get rid of the Hibiscus Beetle?
A. The problem with this beetle is
that it penetrates the buds before they open, making it safe from spraying
materials. The general rule is to apply a follow‑up spray about two days
later. The beetle becomes immune to spray very quickly, therefore rotation of
sprays is necessary. Use Endosulfan, Carbaryl, Diazinon, Mesurol (Methiocarb)
alternately for best results and Dieldrin and Lebaycid occasionally. A suitable
wetting agent aids in applying the spray to give better coverage. Both Diazinon
and Mesurol will cause slight discolouration in blooms for several days after
spraying. Spray when the first signs of beetles are evident, thus preventing
heavy infestation.
Q. When is the best time to spray?
A. Early morning, after the dew is off
the plants and the flowers are open is the best time for spraying. Never spray
your plants in the middle of a hot, sunny day. Be sure to water your plants a
day or two before you spray them, since wilted plants are more likely to be
injured. If a plant is injured by spraying, its leaves will turn yellow and
fall off (over a period of several days). Malathion and Lannate are both likely
to cause injury and should not be used on hibiscus.
Q. Some of my plants have yellow,
rusty spots on their leaves.
A. This is Alternaria and it usually attacks
plants that are deficient in fertiliser during periods of high humidity and wet
weather. Fertilise the plants and spray with either Zineb or Benlate.
Q. The foliage of my plants has become
malformed, stiff, twisted and deeply serrated and the flowers are like plastic
or cardboard.
A. This is phytotoxicity and it is
mainly caused by hormone weedicides, usually 2‑4‑D or 2‑4‑5‑T.
Care must be taken when using these toxic substances anywhere near hibiscus.
Systemic insecticides used regularly or at stronger‑than‑recommended
rates can also cause problems with plants. The plants will eventually grow out
of it. Hard pruning in spring usually helps. Cases of weedi‑ toxicity
have been recorded when neighbours have used these sprays and the slightest
wind has carried the drift onto plants.
Q. Something is eating my plants!
A. Before a cure can be found, the
cause of the problem must be identified. Caterpillars and grubs leave small,
round droppings where they have been feeding. Check for these and spray with Endo‑
Carbaryl or Dipel. Snails and slugs usually leave their silver trails behind,
and often congregate under branches close to ground level. They are always
active on dewy mornings. Spray or bait with Mesurol (Methiocarb) or
Metaldehyde.
Grasshoppers also feed upon
hibiscus look for large holes in leaves that have rough edges. Grasshoppers are
usually easily visible and are best removed by hand as spraying is a little
ineffective unless actual contact is made.
There have also been cases
of plants being eaten by some unknown marauder, and these have been traced to
rabbits, deer, possums and the odd kangaroo or wallaby has also been known to
try hibiscus leaves.
Q. How do I get rid of ants?
A. The answer to this is get rid of
the reason why ants are on your plants and this is usually because they are
attracted to the honeydew excreted by aphids. Endosulfan, Diazinon or Lebaycid
may be used for this. Sometimes ants are attracted by the nectar that forms in
the base of some flowers. A light application of Chlordane around the
base of the main stem will deter them in this case.
Q. Can I use insecticide dusts on my
plants?
A. Yes, in fact many people believe
the dusts have a better residual effect than liquid insecticides.
Q. My leaves are being eaten by a
caterpillar, because I can see its droppings yet I cannot see any?
A. Have a look in the soil just under
the plant and you will most probably find the culprit‑Army Worm. They
feed at night and during the day bury themselves in the soil. They are usually
solitary and are best disposed of by hand once found; however, saturation of
the soil with Endosulfan will control them.
Q. My plants develop black spots and
markings on the leaves, particularly in cooler weather.
A. This is a fungus that attacks some
varieties of hibiscus more than others. Healthy plants resist infection better
than unhealthy ones so fertilising helps, as does early applications of Benlate
or Zineb.
Q. My leaves are curled and twisted
and the flowers not as vibrant.
A. Your plant appears to have developed
a virus which may spread by the use of infected vegetative parts for
propagation and by insect vectors such as aphids and leaf hoppers. Severely
infected or damaged plants should be destroyed and replaced with healthy
plants, and sterilisation of grafting and pruning implements that have been
used on suspect plants is a commonsense practice.
Q. Every winter some of my plants die
back.
A. This is a fungus infection known as
black splash. The disease manifests itself by elongated, dark‑brown to
black areas on the stems or branches of hibiscus. These areas are usually
sunken, and as they grow they join and merge, eventually encircling the branch,
causing it to die. Cut off and burn the affected portions. A spraying of
Benlate will often help in controlling black splash.
Q. My leaves are becoming crinkled.
A. Always check on the undersides of
leaves for aphids. Often they have done considerable damage before they are
detected. Aphids usually are the cause of crinkled leaves. Use Endosulfan,
Diazinon or Lebaycid for effective control.
Fertilising
Q. My buds are dropping off.
A. There are several causes of bud
drop and any one or a combination of several of them may cause the dropping of
buds before they open. Many people are of the opinion that some insect snips
off the buds as they appear to be cut cleanly at the break. This is not so.
Hibiscus simply jettison buds when they are under stress, and they are put
under stress when they do not have enough water or food. Changes in weather and
severe infestation of Hibiscus Beetle may also cause bud‑drop. Ensure
that your hibiscus has regular watering and suitable fertilising. Excessive
amounts of nitrogen in some fertilisers have been known to trigger off bud
drop. Overwatering can often leach some essential nutrients from the soil.
Mulching helps conserve moisture and nutrients in the soil resulting in more
flowers. Hibiscus should never be allowed to dry out in the flowering season or
bud drop will occur. Changeable weather during flowering time may also cause bud
drop, particularly when there is a large difference between the minimum and
maximum temperatures. Heavy infestations of the Hibiscus Beetle will often
cause bud drop and regularly spraying is required to combat this pest.
Sometimes certain varieties carry a bud dropping characteristic and when
hybridised with other varieties, the progeny may have this undesirable trait.
The hybridiser should consider this factor when selecting parent plants. Some
varieties are notorious bud droppers, and full, heavy doubles are more likely
to drop buds than other types.
Q. My foliage is going brown around
the edges!
A. Either too much fertiliser has been
applied or else the plant was not
watered well before and after applying fertiliser. Regular watering will break
down the fertiliser more rapidly, and any excess fertiliser still around the
plant should be removed.
Q. How often should I fertilise?
A. Hibiscus are gross feeders and
require regular fertilising particularly during the flowering period. Nutrients
are leached from sandy soils much faster than heavier clayey soils, therefore
such soils need fertiliser applied more often. In sandy soils a suitable
fertiliser should be applied about every three weeks. In heavier soils every
four to five weeks should be sufficient. At the end of the flowering season a
well‑balanced fertiliser should be applied to carry the plants through
winter. This same fertiliser should be applied after pruning. The regular
applications of recommended fertiliser should begin again in late spring as the
first buds appear.
Q. What is the best fertiliser?
A. Nitrophoska red, Aboska 27,
Nitropep and Redchip are all brand names of suitable fertilisers for hibiscus.
However, these are not available everywhere and therefore a fertiliser with an
N.P.K. of around 13.13.21 or similar should be used. The high percentage of
potash is necessary for continued production of blooms. Consult your local
nurseryman to find a suitable fertiliser. Avoid foliage fertilisers with high
nitrogen concentrations and slow‑release types.
Q. Do hibiscus like manure?
A. Yes. Any kind of animal manure is
beneficial and provides the organic matter necessary to keep plants healthy.
Hibiscus benefit from dressings of manure applied about every five to six weeks
throughout the flowering season.
Q. Will hibiscus tolerate lime?
A. Yes, although hibiscus prefer a pH
of around 6.5 they do well in soils with pH readings from 5.5 to 7.8. When the
pH level of the soil falls below 5.5 applications of lime are required to lift
these levels to a more suitable one for hibiscus. Regular dressings of manure
may also alter the pH levels of soil. In this case a light dusting of lime once
or twice a year is beneficial.
Q. Do hibiscus like foliage
fertilisers?
A. All fertilisers are manufactured to
certain requirements, and should be used according to your needs. Some foliage
fertilisers are high in nitrogen and promote rapid growth in young seedlings
and cuttings; however they may cause bud drop on large flowering plants by
causing too much growth. Others are
more balanced and are ideal to use.
Always read the label before applying, thus avoiding disappointment.
Q. Can I use poultry manure on
hibiscus?
A. Yes, particularly during the
flowering period.
Q. Should I mulch my plants?
A. Yes, mulching is most beneficial in
conserving both moisture and nutrients and helps in keeping weeds down.
Mushroom compost is an ideal mulch; however there are many materials one can
use, and some of these are available more readily in some areas than others.
Q. My plants keep going to leaf.
A. Your plants may not be getting
sufficient sunshine for the wood to harden into flowering wood, or else you are
using a fertiliser with too much nitrogen. There are a few varieties of
hibiscus that flower on older wood, and when these are pruned they tend to
produce a lot of foliage until such time as the wood throws out the short spurs
from which most flowers are produced on those varieties (e.g. 'Wilder's White'
H. arnottianus).
Q. My leaves are turning yellow with
green veinings.
A. You have a deficiency problem. Most
probably it is iron. Use chelated iron or GU 49 iron. Apply a complete
fertiliser and dressing of manure.
Q. What about compost‑can I use
it on my hibiscus?
A. Yes, a compost heap helps return to
the soil what the plants are taking out. Ensure that the compost is well broken
down before application or this process may take some of the available nitrogen
from the soil. A good mulching several times a year is most beneficial.
Q. How do I apply potassium for better
blooms?
A. The use of potassium nitrate to
improve the quality of hibiscus blooms is recommended during the flowering
period. Use at the rate of V2 cup to 20 L water and apply one cup of this
solution to each mature plant. Potassium nitrate is also available in pelleted
form and may be applied dry. Remember when applying either dry or in solution
form you run the risk of burning your plants unless you use very small amounts
at any one time, and water well before and after application.
Planting
Q. Can I grow hibiscus in clayey
soils?
A. As long as good draining is provided, hibiscus will grow in heavier
soils. Where the subsoil is suspect it is a good idea not
to dig into this for planting, but to
raise the level of your garden bed sufficiently to allow for the drainage.
Gypsum helps in breaking down these soils as does the addition of composts and
manures.
Q. My plants in the lawn don't do too
much.
A. If you are to grow hibiscus or any
other shrub for that matter in a lawn, then you must provide an adequate area free
of grass where the plant does not have to compete for food and water. Grass
tends to take all the water and fertiliser away from plants and virtually
starves them to death. The more one waters and fertilises the more the grass
grows. Provide an area about 750 mm (30 in) wide around your plants or better
still make a good garden bed and grow your plants away from the grass.
Q. What depth of soil is necessary to
grow hibiscus?
A. That depends on the size of
hibiscus you want to grow! Most growers prefer to grow the smaller plants
simply because they can fit more varieties in. Naturally you cannot grow a 6 m
high shrub in half a metre of soil. You can, however, grow very good hibiscus
in only 300 mm (1 ft) of soil as long as they are the lowergrowing types. In
some areas where rocky outcrops restrict the depth of soil excellent specimens
of hibiscus are to be seen. It's a little like growing plants in pots, as long
as you keep the plants well watered and fertilised success is ensured. Where
the depth of soil is limited care should be taken to never allow the plants to
dry out and lose condition.
Q. What is the best position for
hibiscus?
A. Full sun all day and protection
from cold winds in temperate areas. Partial shade and shelter from strong winds
in tropical areas. In glasshouses or indoors in very cold areas.
Q. Will hibiscus do well in very sandy
soil?
A. Yes, in fact they prefer sandy soil
as long as liberal amounts of good organic material capable of retaining
moisture and nutrients are added. Usually more fertiliser is required
throughout the season and mulching is necessary during summer, as is plenty of
water.
Q. What is the best time for planting?
A. Here again it depends on your area.
It is not advisable to plant hibiscus during winter in temperate zones, and
although they may be planted the rest of the year late spring and summer are
best. In tropical areas they may be planted all year around. Hibiscus syriacus and other cold‑tolerant
species may be planted during winter when they are dormant.
Q. When can I transplant a hibiscus?
A. The best time for transplanting is
just after pruning in the spring. Plants that are cut back are much easier to
handle at this time. Generally hibiscus will transplant at any time other than
late autumn or winter. Always treat plants with a little Hormone Formula 20
after transplanting for best results.
Q. Will hibiscus grow under trees?
A. They will, grow and survive under
trees but they will never flower or reach their potential unless planted in the
full sun. The trees would compete for food and moisture, resulting in stunted
plants. In tropical areas plants under trees are best if left in pots.
Q. Can I transplant a large hibiscus?
A. Yes, but the question arises is it
worth it? Large plants may require a lot of manpower to move them successfully,
and take a long time to recover. This time could be better used by encouraging
a new, healthier plant to vigorous growth to act as a replacement. The
improvement in modern hybrids suggests that some older plants are best replaced
with better varieties.
Q. How close can I plant hibiscus?
A. This depends entirely on which
varieties you are planting. Some of the lowgrowing varieties can be planted as
close as 60 cm (2 ft) apart; medium growers about 1 to 1.3 m (3‑4 ft)
apart and tall growers around 1.4 to 2 m (4‑6 ft) apart. Space must be
allowed to fertilise and mulch, to keep the plants in tiptop shape.
Q. I have just taken out a large old
plant. Can I plant another in the same position?
A. You can, provided that you replace
the old, burnt‑out soil with fresh, rich material. Plants take certain
trace elements from the soil, and when plants of the same species are planted
in the same spot they rarely do well unless the soil has been completely
replaced or worked over thoroughly.
Pots
Q. How long can I keep a plant in a
pot?
A. This depends on the type of hibiscus and size of pot. Naturally a slow, lowgrowing variety will stay in a pot a lot longer than a more vigorous one.
The rule is they can stay in a pot until such time as they begin to become
unproductive and lose condition. Most plants will stay in a 45‑50 mm (18‑20
in) pot for about five to six years.
Q. My plants in pots are not doing
well.
A. This could be caused by a number of
things ranging from bad drainage or position to incorrect potting mix. Check
these things first, particularly if
you have used general all‑purpose potting mix as this is sometimes not
suitable for hibiscus.
Q. What is the best size pot to use?
A. A 45‑50 mm (18‑20 in)
pot is ideal, however plants may be started in much smaller sizes and gradually
increased until this size is reached.
Q. What is the best pot for hibiscus?
A. This entirely depends on your
choice of material. Hibiscus tend to do well in pots made from various
materials, however it is important to keep in mind that cement and terra‑cotta
containers dry out much faster than plastic ones, or ones made of wood.
Hibiscus do prefer the normal basic pot shape, where the pot diameter is almost
the same as the pot height. They do not do as well in tall 'Ali Baba' type
pots.
Q. Can I plant a small hibiscus
directly into a large pot?
A. Of course. It may even mature more
rapidly than if kept in a smaller container, however a small plant in a large
pot sometimes looks odd, and it is not encouraged for this reason only.
Remember to fight the impulse to plant a few annuals or other plants to fill in
while the hibiscus is growing. Too often these plants take over and smother the
hibiscus.
Q. Do pots need raising off the
ground?
A. Pots raised off the ground dry out rapidly, particularly in windy
positions and plants may lose condition. Pots with bottom drainage if left on a
smooth surface can block up easily, therefore it is a good idea to raise the
pot about 6 mm ( 1/4 in) to allow for better drainage without causing the plant
to dry out excessively. A small section of flat fibro is ideal for this. Pots
with side drainage do not need raising.
Q. How much drainage do I place in the
bottom of a pot?
A. Good drainage is essential to
maintain plants in top condition. After a plant has been in a pot for several
years the drainage holes tend to clog. For this reason plenty of drainage is
required when planting hibiscus in pots. Roughly one‑quarter the height
of the pot should be used for drainage material. Old, broken tiles or pots,
coarse clinker ash, and rough pebbles may all be used for drainage and covered
with a layer of ashes or gravel which will act as a filter to prevent soil
blocking the holes. Do not block off the drainage holes with material; they have
to be free to allow the passage of water.
Q. How often do I water and fertilise
plants in pots?
A. A good watering every second day
should be sufficient for most plants, depending on the weather. This regular
watering tends to leach out the essential nutrients more quickly than if the
plants were in the ground. Therefore the fertiliser has to be applied to the
plants more regularly than if the plants were in the ground. Fertilise about
every two to three weeks throughout the flowering period.
Q. When is the best time for potting
and repotting hibiscus?
A. Any time except winter is all right
for potting and repotting, although mid to late spring would be the ideal time.
The plants have been pruned and are easier to handle then. Old, neglected
plants can be pruned heavily and root pruned and repotted into fresh soil in
the spring.
Q. What is the best soil for hibiscus
planted in pots?
A. Every nursery will tell you that
hibiscus will do well in the particular soil mix that they are selling, and
sometimes this is true; however from past experience it is best to get soil
from a specialist grower or mix your own. Hibiscus like a free‑draining,
open mix with a good amount of humus. Two parts sandy loam, one part peat moss,
one part cow manure or mushroom compost and one part coarse river sand makes an
ideal mix for plants in pots that are to be left outside all the time. If you
are in a colder area it is better to use only one part sandy loam, particularly
if your pots are to be moved indoors during winter. It is best to avoid pre‑packed
soil mixes that are based on composted sawdust.
Q. What is the best position for
hibiscus in pots?
A. The more sun hibiscus are given the
better, therefore they will do well in any position in the garden, be it a
sunny patio or deck, courtyard or wall, providing full sun is provided. One of
the main advantages of hibiscus in pots is that you can make them mobile,
following the sun around. This is very useful during winter when these plants
like that little extra warmth.
Hybridising
Q. What is the best time to hybridise?
A. Even before‑the blossom
opens, the stigma pads are receptive to pollen, therefore early in the morning
is the best time.
Q. How does one hybridise?
A. Hybridisation is simply crossing
two plants together to produce progeny that hopefully will have the desirable
traits of both parents. It involves dusting the male portions of flowers
(pollen) onto the female part of the flower (stigma or pistil). In hibiscus this is easy as
the pollen sacs are a cluster of yellow anthers prominant on the staminal
column, and the stigma is recognised by the five stigma pads at the tip of the
column. Each of the five stigma pads must be dusted with pollen either with a
soft brush or the bloom of the pollen parent may be picked and the pollen
applied directly.
Q. What time of year is best for
hybridising?
A. Some growers hybridise most of the
year around; however mid‑autumn to early spring is best. In cooler
weather, the humid and foggy days are ideal. High temperatures dry out or
inhibit the pollen so that it is not viable.
Q. How deep should I plant seed?
A. Make a depression the size of a
finger tip and 6 mm (%4 in) deep in the soil mix, then cover the seed with more
mix.
Q. How long do the pods take to ripen
after hydridising?
A. The pods may take anything from
forty to seventy days. They must be watched carefully as they begin to ripen,
lest they burst and the seed is lost.
Q. What do I sow seed in?
A. There are numerous seed mixes to
use. Some growers have good results just using compressed fibre blocks. A
mixture of sand and peat and ground‑up sphagnum is ideal. Vermiculite and
peat, perlite and peat, milled mixture of sphagnum and vermiculite or sterile
soil may be used as well. Sometimes it is a good idea to try several mixes out
and use the one that gives the best results in your area.
Q. How long does it take seedlings to
bloom?
A. Most seedlings will bloom in 10 to
14 months, provided that they are not cut back as this delays blooming. Plants
grown in full sun will flower much quicker than those grown in shaded
positions.
Propagating
Q. When do I take cuttings?
A. Hibiscus may be grown from three
different types of cuttings: tip cuttings which are taken in summer; firm wood
cuttings which are taken in autumn; hardwood cuttings that are taken in late
winter or early spring.
Q. What do I put the cuttings in?
A. Most cuttings do best if placed in
small individual pots. A mixture of sand and peat, perlite and peat or washed
river sand should be used.
Q. When can I graft?
A. The best time for grafting is
during summer and autumn using the side graft
method. Tip or cleft grafting is
better when done in the spring.
Q. Can I graft several varieties on
to one understock?
A. You can, but unless you only have
limited space to grow just one plant it is not recommended. After a while one
variety will begin to dominate the others, reducing their vigour. Two varieties
on the one understock is sometimes very interesting.
Q. What understock is best?
A. This depends on your area. (Different
growers use different understocks in different areas. `Ruth Wilcox' (`Albo
Lacinatus') or `Wilders White' (H.
arnottianus) are the best overall; `The President' and `Pride of Hankins'
(`Landersii') are good for some areas.
Q. When do you cut the plastic tapes
from your grafts?
A. Once you are sure you have a good
union formed between your understock and scion, you should cut the tape to
prevent constriction. It is best to do this eight to ten weeks after grafting.
Q. When is the best time to sow `Southern
Belle' seed?
A. The best time is in early spring.
`Southern Belle' will usually flower within a season in warm districts.
Q. When do you cut off the top part of
the understock from a side graft?
A. This varies, however the general
rule is when the leaves on the scion become mature enough to function properly
and support growth for that plant.
Q. How long do I leave cuttings before
they take root?
A. This again depends on the area
where the cuttings are. Most cuttings should strike within eight to ten weeks.
It is better to discard cuttings that take longer than, say, fourteen weeks to
strike as they generally don't produce strong plants.
Q. How long should cuttings be left
before they are potted?
A. Once cuttings are rooted and the
root system is sufficiently strong the earlier the better. Cuttings progress
much more rapidly once planted in good soil. Cuttings left in propagating
materials lose condition if left too long.
Q. Someone said to throw a plastic bag
over my cuttings. Is this right?
A. Cuttings strike better if kept in a
warm, humid atmosphere, particularly tip and medium wood cuttings. Covering
them with a plastic bag is an excellent way to provide this atmosphere. The
plastic may be removed regularly to prevent a buildup of fungus diseases which
also proliferate under these conditions.
Flowers
Q. My double flowering hibiscus has
turned single.
A. Hibiscus blooms are governed by the
weather conditions and produce their best blooms during summer and autumn.
Flowers produced outside these times are sometimes out of season and we have
doubles reverting to singles and flowers getting smaller in size and deepening
in colour. The flowers will return to double as the new season approaches.
Q. My flowers only last a day then
drop off!
A. The hibiscus flower only lasts a
day, although many new hybrids have been bred which now last longer, even up to
three days. Do not think of this as a disadvantage; remember that many plants
bloom but once a year for only about two to three weeks and although their flowers
may last longer, they are often damaged by wind, rain and insects and one has
to wait another year for a repeat performance. With hibiscus a new flower
replaces the old one the next day; a guarantee of fresh flowers all the time
over seven or more months a year,'
Q. My hibiscus was red with white
splashes, now it is only red!
A. Another case of flowers out of
season. The white spots will reappear as the warm weather returns. Most
hibiscus with spots or splashes of different colours lose these in the off season.
Q. My blooms sometimes open with
rolled edges!
A. This is caused by the early morning
sun hitting the flowers when they are covered with dew. It is often caused also
by overhead watering during the heat of the day.
Q. My flowers sometimes miss a petal!
A. The flowers don't actually miss a
petal, they will still have five, but some varieties, particularly the semi‑doubles
with large exaggerated staminal columns, often produce these blooms. This is
called crippling and it is just the variety that bunches the petals around the
staminal column causing the gap in the petals.
Q. How do I transport blooms without
damage!
A. It is very hard to transport blooms
that have already opened, therefore the trick is to pick them in the bud stage
as they are about to open and place them in paper cones or drinking cups. The
buds when removed from the cups will open spontaneously. Do not place them in
styrofoam containers since petals will often stick to them and are torn on
removal. Buds may also be packed tightly in boxes, where again upon removal
they will open.
Q. Can I make my blooms last longer?
A. Hibiscus blooms will not last any
longer whether they are left on the bush or picked, whether they are placed in
water or not, and they do not usually last any longer when placed in a
refrigerator. The refrigerator will however postpone the opening of buds for a
day or so, but the flowers themselves will last no longer once they open. Select
varieties that last longer for a start. Many new hybrids last considerably
longer than older varieties.
Watering
Q. How often should I water?
A. A good watering twice a week in the
middle of the season is more beneficial than a light watering every day.
Naturally plants may require more watering to keep their condition during a very
hot dry spell.
Q. When is the best time to water?
A. Late afternoon or twilight is best.
Avoid watering during the heat of the day.
Q. Is a sprinkler system good to use
for hibiscus?
A. Sprinkler systems are very good,
however overhead watering may sometimes damage buds. Care must be taken to
observe the time of day they are to be used. Later afternoon is best.
Q. How much water should I give my
plants?
A. Too much water causes as many
problems as too little. Maintain a good moisture level in your soil without it
remaining soggy. Too much water also leaches valuable nutrients from the soil.
A good soaking equivalent to 25 mm (I in) of rain about twice a week would be
ideal.
Q. Is trickle feed irrigation any
good?
A. Yes, a number of growers have had
excellent results using this method of watering.
Q. When watering should I hose the
whole plant or just the soil?
A. It is better to apply the water to
the soil most of the time, however a good hosing of the foliage every now and
again helps keep the plant clean. Dust and grime builds up on the leaves in
some areas and regular hosing will remove this. Near the coast watering of the
foliage after a salt‑laden wind is recommended to reduce build up of salt
on the foliage.
Pruning
Q. When should I prune my hibiscus?
A. The best time for pruning the rosa‑sinensis
types is spring; H. mutablis and syriacus varieties should be pruned in winter.
Q. How much do I cut from my plants
when pruning?
A. Most hibiscus relish being cut back
about one‑third all over. There are a few exceptions of course which do
better when left unpruned. Plants that are very woody can be cut back half way
or more to induce new, healthy wood.
Q. My weeping hibiscus isn't weeping!
A. The weeping or waterfall hibiscus `Ruth Wilcox' (`Albo Lacinatus') is one
hibiscus that does better when left unpruned. If it is pruned each year it
produces nice long, straight canes that give very few blooms, if left unpruned
these canes begin to weep and produce smaller laterals which become covered in
flowers. A severe pruning every five to six years will maintain this variety in
good condition.
Q. My plants are very straggly!
A. They require pruning to maintain a
nice rounded habit. Remove all lower, straggly branches, and trim the plant
back one‑third in spring.
Q. Why do you have to prune?
A. There are several reasons for
pruning, the most important one being that pruning promotes strong healthy
growth which in turn produces the best flowers. It is also used to remove old,
decayed and diseased wood, and to keep the plant in a desired shape.
General
Issues
Q. How long do hibiscus live?
A. This depends a lot on its position
and care. Most plants begin to lose condition around twelve to fifteen years,
however there are many specimens well over fifty years old around, particularly
of the early hybrids.
Q. My grafted hybrid hibiscus was a
large yellow variety that was rather slow, now it is growing vigorously and
producing small pink flowers.
A. The understock has taken over.
Hybrid hibiscus are grafted onto stronggrowing, hardy understocks, and
sometimes if an eye has been left, this stock begins to grow and if not cut off
early it will completely dominate the
grafted variety. Usually these
understocks have a different leaf which makes identification easier in the early
stages.
Q. My hibiscus don't begin to bloom
until late in the season.
A. They are probably not getting
enough sun. Check the sunlight situation first; if they are getting full sun
then more than likely something has happened to your growing tips‑possibly
damage by tip‑borer. If that's the case spray regularly during spring
with Endosulfan.
Q. Why are Hawaiian hibiscus not as
hardy as others?
A. Hardiness depends entirely on the
variety. Most modern hybrids are loosely called Hawaiian hibiscus when many of
them have been bred in Florida or Australia.
Because they are complex hybrids, it is true that some of them may have lost
their vigour through years of hybridisation, in an effort to produce more
spectacular blooms. In most cases this lost vigour has been restored by
grafting these varieties on to hardy rootstocks making them perform well. Some
modern varieties however are just as vigorous and hardy as some of the old
ones.
Q. My `Southern Belle' type of
hibiscus keeps breaking!
A. These herbaceous hibiscus are very
prone to wind damage and must be planted in a sheltered position. They do
better when four large stakes are driven into the ground about 45 cm (18 in)
apart around the base of the plant and then strong wire netting wrapped around
the four stakes holding the canes in an upright position. It is important to do
this just as the shoots begin appearing in the spring, otherwise damage will be
done to the plant.
Q. Are there any Australian native
hibiscus?
A. Yes, there are over thirty‑five
different species of hibiscus indigenous to Australia, with Hibiscus splendens possibly the most
spectacular. The so‑called blue hibiscus of Western Australia has since been
reclassified and is no longer recognised as a true hibiscus but as Alogyne huegelii. The blooms on some of
these plants last only for a few hours.
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