Gardening Australia – September 2019

(Jacob Rumans) #1

PLANTS


GARDENING AUSTRALIA SEPTEMBER 2019 31


PLANTING & CARE
Hibiscus are sun worshippers, and flower poorly in shade. In cooler
areas, they perform best near a warm north- or east-facing fence
or wall, sheltered from wind. They grow well in coastal gardens
but need protection from strong, salty winds.
The time to plant is October to December in temperate areas,
early spring to early autumn in the subtropics, and after the Wet
in the tropics. Good drainage is essential, so choose a spot on a
slope, or make a slight mound in clay soils, and avoid low-lying
areas where puddles form. A soil pH of 6–6.5 is ideal.
The plant’s roots are generally located in the top 30cm of soil,
so dig a wide hole to about that depth and incorporate lots of
well-rotted manure or compost. Water well after planting, and
stake tall plants if they need support. Apply a 5cm layer of organic
mulch to help retain soil moisture and encourage biological
activity, but keep it away from the trunk.
Flowers appear on new growth, potentially from each leaf axil.
Hibiscus are responsive to a general garden fertiliser containing
trace elements, applied monthly during the growing season.

PRUNING
Prune to improve plant shape and encourage more flowers. Some
cultivars require little, if any, pruning. It’s best to prune as the shrub
surges into growth. This is in early spring in subtropical and warm
temperate areas (following frosts), and after the Wet in the tropics.
Generally, prune hibiscus by no more than one-third, as they can
respond poorly to heavy pruning. To rejuvenate an old shrub, it’s
better to prune in stages, reducing its size gradually over a couple
of years. Remove dead or diseased wood, and shape the bush.

PROPAGATION
Hibiscus are one of the easier shrubs to propagate. In the warmer
months, take semi-hardwood cuttings the length and thickness
of a pencil. Remove all but the top two leaves, trim the base just
below a node, then plant in a pot filled with coir peat. Put a plastic
bag over the pot to maintain humidity around the cutting, place it in
a warm, shaded area, and keep moist until new growth is visible.

TROUBLESHOOTING
Under ideal growing conditions, hibiscus are subject to few
pests and diseases. Issues generally relate to cultural practices.
In cooler areas, plants may suffer during the first few winters
until they become established. Common issues include:
Defoliation This may be an indication that the plant is in shock
because it’s too cold or too wet.
Yellowish leaves Generally a sign of poor nutrition, but this can
occur in alkaline or salt-ridden soils, and in winter in cooler areas.

TROPICAL&SUBTROPICAL
Hibiscusschizopetalus
H.‘Archeri’(‘Psyche’)
H.‘ElCapitolio’
H.‘PinkDainty’
H.‘PinkVersicolor’
(‘RuthWilcox’)
H.‘SprinkleRain’
H.‘WhiteVersicolor’
(‘SwanLake’)
H.‘SnowQueen’
(variegatedleaf)
H.‘Roseflake’
(variegatedleaf)
Fijianhibiscusgrowwell
Hawaiianhibiscus
(preferablygraftedplants)
canbegrownwithextra
careanddedication

WARMTEMPERATE
Fijianhibiscus
Hibiscusarnottianus
H.‘AgnesGault’
H.‘Andersonii’
H.‘AppleBlossom’
H.‘Dawn’
(‘WoodrowWilson’)
H.‘FijiPink’
(‘WinterShow’)

H.‘GeneralCorteges’
H.‘GoldenQueen’
H.‘HawaiianSkies’
H.‘KingofTonga’
H.‘Lollipops’
H.‘RossEstey’
H.‘WhiteDainty’
H.‘WhiteWings’
H.‘IsobelBeard’(double)
H.‘Kona’(double)
H.‘Sabrina’(double)
Hawaiianhibiscus
Graftedplantscanbegrown
inwarm,shelteredlocations,
orinpotswheretheirneeds
canbemetbyexperienced
anddedicatedgardeners

COOLTEMPERATE
BothH.syriacusand
H.mutabilisarefrost-hardy
andmaybebestforcooler
climates.Alternatively,grow
newcompactFlamencoand
RioClarahibiscusaspotted
ortemporarybeddingplants
Fijian hibiscus cultivars
can be grown in pots. Store
in a greenhouse during winter,
and move outside in summer

PLANTS FOR YOUR CLIMATE


Hibiscus are readily
available in nurseries, or
try the following suppliers:

where
to
BUY

Lack of vigour Caused by too much shade, too cold, too dry,
poor drainage or poor nutrition.
Bud drop Cool weather, too wet or too dry, or poor nutrition.
Pests Sap-sucking mealy bugs, aphids, scale and whitefly are
generally associated with stressed plants. The plant may require
feeding, watering or moving to another location. If the pest
problem persists or is severe, spray the plant with neem oil. GA

Virginia Nursery, Virginia,
SouthAustralia,(08) 8307
6800,virginianursery.com.au
Florez Nursery,
Wollongong, New South
Wales, 0412 123 240,
floreznursery.blogspot.com

PHOTOS


ARNO KING, MARIANNE CANNON, LEX THOMSON, AWARD PLANTS, KIM WOODS RABBIDGE, PROPAGATION AUSTRALIA

Free download pdf