WHAT IS A CACTUS?
word "cactus" is actually derived from the Greek word
"Kaktos", which is actually a species of a
spiny thistle belonging to the daisy family (Asteraceae).
Cacti leaves have been reduced to spines in order to reduce the
rate of transpiration during photosynthesis. The spines have 2
functions. First, they help to protect the plant from thirsty
animals since the plant is full of sap. Secondly, the spines help
to reflect the light rays of the glaring hot sun to prevent burns.
Cacti have swollen stems to store water in order to survive in
deserts with very little rainfall.
Cacti have areoles which are characteristic of cacti as it is
from these where spines, flowers or offsets will arise.
Cacti have one of the most beautiful flowers among flowering plants.
Some are so vividly coloured that they are almost inflorescent
in order to attract insects for pollination under the glaring
hot sun in a desert.
Cactus with ribs
Above: Parts of a ribbed cactus, Parodia.
help to shade the cactus from the hot desert sun at any part of
the day. Flowers usually rise from the areoles near the apex depending
on the cactus genera.
Cactus with tubercles
Above: Parts of a cactus with tubercles.
help to shade the cactus from the hot desert sun at any part of
the day. It should be noted that flowers for this class of cactus
ie the Mammillaria genus, arise between the tubercles and
not from the areoles.
Cactus with pads
Above: Parts of a padded cactus, Opuntia.
the ribs and tubercles, pads help to shade the cactus from the
hot desert sun at any part of the day. Cacti belonging to the
genus Opuntia have an upward growth habit. Once the pad
has matured, it will stop growing. New growth will appear from
the areoles of this matured pad and the process starts all over
again. It should be noted that some of the genera have glochids
which are actually a collection of very fine spines which may
cause rashes to people with sensitive skin.
IS A SUCCULENT?
left: Aloe mitriformis is a leaf succulent.
Above right: Opuntia monacantha variant is
Below left: Pleiospilos nellii is a leaf succulent.
It is virtually stemless.
Belw right: Crassula perforata is also a leaf
word '"Succos" in Latin means juice or sap. Thus,
a succulent is a plant with water storage organs thereby enabling
the plant to survive over a period of drought. Water can be stored
in their leaves, stems and roots. They do not have spines.
Some succulents exude a milky sap when damaged. It should be noted
that a cactus is a succulent but a succulent may not be a cactus.
Cacti are stem succulents since water is stored in their stems.
They do not have leaves and their roots are not fleshy too.
CULTURE OF CACTI AND SUCCULENTS
is the main problem in many high rise apartment gardeners as not
every one of us is blessed with a sunny balcony or a common corridor.
Most cacti and succulents require at least 6 hours of direct sun
or very bright light in order to stay compact. Lack of light will
cause them to etiolate which will make them vulnerable to pests
and diseases later. Most of their flowers require good light in
order to open fully.
I find that most cacti and succulents hate to be grown under the
shade of other plants. They like to be grown in an open space
with no obstructions. On the other hand, houseplants do not like
to be grown with them either and will be stunted in the direction
where you place the cactus. They dislike spiny plants that tear
has to be very free draining in order to grow them successfully
as any pockets of stagnant water in the soil medium will cause
roots rots. In high rise apartment gardening, it is crucial for
the soil to be dry up by the third day after watering. Commercial
mixes contain too much peat which is bad for cacti and succulents.
Peat is too wet when watered and too dry when dry. Besides, it
is very difficult to wet peat after it has dried up. In countries
with low humidity, they make very suitable potting media but in
the tropics, they break down easily and you may need to repot
your cactus annually. Cacti and succulents dislike root disturbances
and thus, it is not wise to undergo this operation annually. It
is better to use loam-based potting mixtures as they are generally
free of peat. Sadly speaking, most of the imported cacti and succulents
sold in our local nurseries are potted in peat and it is recommended
to repot them in a loam-based mix.
left: Most of the commercially available burnt earth is
too fine. These fine particles need to be removed before use
as they will cause future drainage problems.
Above right: Aquarium gravel which can be acquired
at all aquarium shops.
Middle left: I usually use top soil as a substitute
for aquarium gravel for the hardier cacti and succulents to
Middle right: Perlite will break down after a year
and drainage may be affected. Repotting may therefore be required.
Below left: Peat should be avoided in all cactus and
succulent potting mixture.
Below right: The resultant mix of 2 parts sifted burnt
earth and 1 part top soil. Note the grainy texture of the
prefer to mix my own soil for my cacti and succulents as follows:
Sifted burnt earth (50%) and diatomite (50%). Of course, this
is not the only mix that you can use. However, it is recommended
to use at least 50% of soil which can be your burnt earth or any
commercial cactus mix. The other 50% will comprise soiless medium
for drainage enhancement like aquarium gravel, perlite, vermiculite,
coarse sand, charcoal chips etc in varying proportions. You have
to experiment the type of soil mix that is suitable in your area.
is very common to hear advice from nurseries that cacti and succulents
require very little water and can survive weeks with no water.
Cacti and succulents contain at least 75% water and sometimes
I just wonder how the poor plant can grow well when there is no
water in the first place. They need water just like our houseplants.
not forget they are not in the desert. They do not have long roots
to search for underground water. They are confined in that little
pot that you give them. If you do not water them, who will? Some
of you may be surprised that desert rains are in fact very heavy
and can last for days or even weeks. During this period, the whole
desert will be in full bloom and most of the plants will grow,
bloom and even fruit before the soil turns dry again.
them generously when they are in active growth and sparingly when
they are dormant or resting.
to know my cactus is growing?
spines at the apex, which is the growing tip of the cactus, will
suddenly start to turn to a very bright red or yellow depending
on the cactus genera. Then a cluster of spines will appear at
the apex and it is now time to water your cactus.
protect your cacti and succulents from rain as too much rain will
cause our beloved plants to rot especially when they are resting.
water your cacti and succulents when the top inch layer of the
soil has dried up a little. You should water in the morning to
prevent any possible fungal or viral infection.
your cacti with a container containing a long nozzle. You can
also use a pressure jet to water your cacti taking care not to
wet the stem. Never hose down your cacti and succulents like your
houseplants. Aim the nozzle at the side of the pot to allow the
soil to absorb the moisture. Dry soil absorbs water very fast.
pots are proven to be better than plastics. If you can afford
it, go for it. Beware of overpotting. I have seen a small cactus
barely 6cm across potted in an eight-inch pot. The soil takes
too long to dry out and may cause the cactus to rot. Always pot
the cactus no bigger than half an inch between the cactus body
and the edge of the pot. Stagnant soil provides breeding grounds
for root mealy bugs.
happen if I do not have a small pot?
your cactus in very well drained mix with a thick layer of aquarium
gravel, perlite or sand at the bottom of the pot under a very
bright location in an airy place. Something like a desert.
may be surprised that desert soil is very fertile. Who says cacti
and succulents do not need to be fed? In fact, you should feed
them generously at half strength of the recommended dosage stated
by the manufacturer weekly for good results. I prefer soluble
fertilisers as the organic ones may burn the roots when the cactus
is resting. Use a low nitrogen fertiliser if you can. For myself,
I use a generic plant fertiliser for my cacti and succulents to
Root Mealy Bugs
than overwatering, root mealy bugs is the number one killer of
our cacti and succulents. Root mealies like to attack cacti and
succulents and it is very difficult to eradicate them. Prevention
is better than cure. I always water my cacti and succulents with
a solution of malathion weekly to prevent any possible attacks
from the root mealies.