by Jerry Parsons, Ph.D.
Horticulture Specialist, Texas Agricultural Extension Service
in San Antonio
As hot and dry as the summers in Texas are,
some people wonder if there is anything that is really easy
to grow during the dog days of June through September. For
those of you who want to grow a low maintenance plant, you
may want to consider cactus.
Why would anyone want to grow cactus?
Primarily, ease--if you can't grow cactus, we
can't help you! Can you imagine anyone having the nerve to
admit they've killed a cactus?!
Cacti are a group of plants that are not only
easy to grow, but offer a variety of shapes, color and form.
They can be grown in any sunny, well-drained area. They require
little maintenance. They make excellent houseplants and many
hardy varieties may be grown outside.
If you want small specimens (less than one inch
above the ground), you will want to grow lithops, which is
Greek for "living rocks". Other cacti which mimic
the appearance of rocks include titanopsis, lapidaria, penestraria
Some cactus and succulent types can be used
as pot plants. These include Aloe Vera, crassulas, Echeverias,
peperomias and kalanchoe.
Larger-growing cactus and succulent plants make
dramatic floor plants with heights from 3 to 10 feet or more.
These include Cereus peruvianus, Yucca elephantipes, Euphorbias,
ponytail palm or bottle palm.
The cactus family (Cactaceae) is one of the
most striking, distinctive, diversified and specialized groups
in the plant kingdom. It includes about 2,000 species, and
all of them are perennial and succulent.
Succulents are plants that have organs such
as leaves, stems or roots that are capable of storing water
during the rainy or wet season in order to survive extended
periods of drought. All the plants in the cactus family (Opuntiacea
= Cactacea) are considered stem succulents. During periods
of moisture, the stem swells. Then during droughts, the stem
slowly contracts. Cactus that have ribs are particularly well
adapted to this because the ribs fill in and contract like
The cactus flowers are usually conspicuous,
and are so different from those of all other plant families
that the cacti are unique and alone, without obvious relationship
to other plants. Epiphyllum, the orchid cactus, leads this
category with its fragrant flowers that grow up to 8 inches
The distinctiveness of the cactus family shows
itself not only in the flower structure, but also in one characteristic,
that, although possessed by every cactus plant, is absent
in all species of all other families. This is the spine cushion
or areole. Whether or not spines are present, all cacti have
areoles. Because these areoles differ in structure on different
kinds of cacti, this is one way of distinguishing one cactus
plant from another.
An areole is the radial arrangement of spines
on pad-like buds where shoots and flowers may appear. The
areoles themselves are arranged in a regular pattern, either
along the ribs of columnar or barrel cacti, or at equally
spaced intervals over the face of pad-like cacti. In some
cactus species, such as the Christmas cactus (Schlumbergera
sp.), the areoles are difficult to see as they are very small
and grouped at the tips and along the sides of the stem segments.
One plant family that is often confused for
the cactus family is the euphorbia family (Euphorbiacea) which
contains such plants as Cow's Horn Cactus (Euphorbia grandicornis),
African Milk Bush (E. trigona) and Crown of Thorns (E. milii).
While all these plants have spines, have green stems and few
or no leaves, they do not have areoles. If you are still in
doubt about whether you have a euphorbia or a cactus, make
a small cut in an inconspicuous place. If the sap is milky
white and sticky, then you have a euphorbia, since cactus
sap is clear and watery.
Here is a frequently asked question: "Is
this plant a cactus or a succulent?" This question is
nonsensical because cacti are succulents. The true cacti are
members of the botanical family Cactaceae and are distinguished
from the succulent members of other plant families such as
Euphoribiaceae by the structure of the flower and the presence
of the areoles on cacti. It therefore should be: "Is
this plant a cactus or some other succulent?"
Cacti are native only to the Americas. Christopher
Columbus is purported to be the first European to discover
this spiny, leafless plant. Of course, Native Americans knew
all about cacti. It was incorporated into many Native American
cultures. Cactus sap has been used medicinally. Some cactus
sap has a narcotic effect and has been used in religious ceremonies.
The sap of Stenocereus gummosus is toxic and is thrown into
streams where it stuns fish which are then easily caught by
hand. The stems of some cacti can be used as a source of food,
either baked or eaten raw. Cactus fruit of some species are
eaten raw, and also candied or preserved in jams.
Certain parts of the cactus are edible too.
In April and May, cactus plants make new growth. The new growth
are not new leaves but stems. Leaves are about ¼ inch
long and the diameter of a pencil lead. They fall off in a
few weeks, before the new stem or pad fully expands. The leaf
scar is located at an areole from which the spines begin to
emerge after the leaf falls. The areole is also capable of
sprouting a new stem (which is the same as an auxillary bud).
When nopales (nopalito means small) are cut
or harvested in the young and tender stage, there are usually
no spines yet developed. Nopales are taken only from prickly
pear (nopal) cactus. The red fruit are called tuna (a Spanish
word) and also have spines. The little stems, or pencos, are
light green and as crisp and tender as lettuce. Nopales are
a favorite Mexican vegetable, with flavor and texture similar
to green beans, but firmer. The smaller leaves are more tender.
To prepare for cooking, the cactus thorns must
be removed, carefully, with a potato peeler or sharp-pointed
knife. To prepare abut 20 small, tender Nopales, cut the de-spined
Nopales into ½ squares and boil in salted water with
¼ teaspoon of soda and one chopped onion for 5 to 10
minutes, or until the Naoales are tender. Drain, season to
taste and serve.
Cactus has also had other practical uses. The
long, soft spines of Oerocereus celsianus are used as pillow
and bed stuffing. Spines of other cacti are used as toothpicks,
combs, sewing needles and fishhooks. Yet other cacti are used
as building materials and as living fences or hedges.
One the earliest recorded cultivation of a specific
cactus species for a specific purpose was by the Aztecs. They
grew Opuntia coccenillifera which acted as a host to the cochineal
scale insect. It was harvested and crushed to produce a dye
that was either a rich purple (from the female scales) or
a brilliant scarlet (from the male scales). The dye was used
in fabrics and cosmetics.
The first step to successfully growing a healthy
cactus plant is to purchase one that is already in good health.
Avoid any plant that has damaged spines, obvious signs of
bruising, or that has lopsided or uneven growth. A plant that
has put on new, spindly growth during its time in the store
should be avoided. Even under ideal growing conditions, the
spindly growth produced in a dimly-lit store will never broaden
out to normal size, leaving the plant with a permanent disfigurement.
Ideally, a cactus should be purchased in the greenhouse where
it was grown, or as soon as possible after it has been shipped
to a retail outlet.
The care a particular type of cactus requires
is largely dictated by the climatic conditions where that
cactus would be found growing in nature. A good rule of thumb
for looking after any plant is to provide conditions that
are as close as possible to the environment where the plant
would be found growing naturally.
Generally, the 2 most common classes of cactus
are those which are l) sun-loving and 2) shade-loving. A potting
medium composed of equal volumes of coarse sand, peat and
perlite is suitable to grow most cacti. Vertical plants should
be planted in a container that has a diameter ½ the
height of the plant. Plant Round cacti in containers that
have a diameter 2 inches greater than that of the plant. Take
care to prevent rot from developing on recently potted or
repotted plants. Be sure the pot is dry before transplanting,
and transplant into dry soil. Wait a week before watering
to allow for the damaged roots to repair.
The quantity and frequency of watering provides
one of the biggest dilemmas to cactus owners. Since a cactus
does not wilt at the first sign of drought stress, the plant
offers few cues that it needs water. A good rule of thumb
is to water when the top 2 to 3 centimeters of soil is dry.
This should be adjusted with the season.
However, as plants will require more water during
the period of summertime growth than they will during the
slowed, or halted growth of winter. In winter, the plants
may require water only once a month. During winter, you should
supply just enough moisture to prevent the roots from drying
and dying. One of the most important considerations in watering
a cactus is to never let the pots stand in water.
Waterlogged soil can quickly lead to rotting
of the roots with disastrous consequences for the plant. Cacti
do need to be watered and fertilized, but not as frequently
as other plants. Water the pots when they dry out and allow
the soil to dry thoroughly between watering. Do not water
during rainy spells, during winter or immediately after repotting.
Some varieties have dormant periods when watering can be very
harmful. Unglazed clay pots require more frequent watering
than glazed clay or plastic pots. Small pots require more
frequent watering than large pots.
Cactus and succulents need, at the least, very
bright light to maintain good color and shape. Spiny, fuzzy
or hairy varieties generally require more sun than do the
smooth, soft, leafy types.
While most cacti tolerate a wide range of growing
temperatures, most will do best at temperatures similar to
that of most other houseplants. When temperatures are either
too hot or too cold, a cactus will often simply go dormant.
An ideal placement for a cactus in winter would be a sunny
cool room. During the summer, cacti will appreciate being
moved outdoors where they can receive brighter light in combination
with cooling breezes during the day and cool humid conditions
at the night. If you are moving your cactus outside for the
summer, be sure to place it in a position of partial shade
for the first few weeks, and slowly move it to a sunnier location.
A plant going directly outside into full sun will likely be
scorched by the more intense light found outside the home.
Cacti can be propagated from branches or offshoots.
The offshoot should be removed from the plant and allowed
to dry for 2 weeks. After the broken or cut edge has healed
or suberized, plant it shallowly in dry medium. When taking
a cutting from a stem section, use a clean, sharp knife. If
you are taking several sections from one long stem, you must
remember which was the top and the bottom of each piece, because
a stem piece that is planted upside down will not grow.
A simple way of keeping track of the top and
bottom is to cut the bottom of each segment on a slight angle,
and the top straight across. For pad-forming, or branching
cacti, the cuttings should be taken at the joints so that
the mother plant is not significantly disfigured. A single
oval pad from a pad-forming cactus makes an ideal sized cutting.
The primary problem with cactus cuttings is
the development of fungal soft rot. This condition begins
at the cut surface and eventually reduces the entire cutting
to a slimy mass. Two techniques are recommended for avoiding
this problem. The first is to simply allow all fresh cuttings
to sit in a warm dry place from one to 14 days before they
are placed in the rooting medium. The larger the cut surface,
the longer they should be allowed to dry. During this time,
the cut, moist surface will form a dry callus that is far
less prone to rot. Although leaving a new cutting exposed
for several days may seem like a radical idea, remember that
a cactus is able to survive periods of drought. As long as
the cutting is not noticeably shriveled, it is probably okay
to leave it dry. Newly cut stem segments may also be dipped
in garden sulphur before planting to prevent the onset of
soft rot. Do not water the cutting for a week, then water
Cacti can also be grown from seed, and many
seed companies offer packets of mixed varieties. These can
be fun to grow if you can stand the suspense. Some cacti seed
take a year to germinate, and it may take a few years to see
what your young cacti will look like.
Despite their slow germination, cacti are no
more difficult to raise from seed than many half-hardy plants.
Many can be flowered within 2 years or even earlier after
sowing the seed. It's possible to get a fine collection within
in a few years.
The time of the year for sowing seeds depends
on what conditions are available. If you have a greenhouse
and a small, heated propagator, it is possible to sow your
seeds at the end of January or early February. However, if
heat is not available, it would be better to wait until late
April or early May before attempting to sow your seed.
The earlier the seed is sown the larger the
seedlings grow before the winter sets in. This is a very important
point. It is never easy to get small seedlings through the
winter without heat, and the stronger they are by the middle
of October, the better the chances are that you will see them
through the cold season. Some varieties are extremely slow
while others are much faster. Maintaining the heat in your
greenhouse in the 40 to 45 degrees F range will help considerably,
and the seedlings will make an earlier start into spring growth.
The best compost for raising cacti is a potting
mix. The addition of extra sharp sand is very helpful, especially
for the top inch of compost.
Four-inch half-pans have been found to be very
suitable for seed growing because they do not dry out too
quickly. Make sure all pans are sterilized and clean before
sowing. If only a small quantity of seed of each variety is
being sown, the pan can be divided into sections using thin
strips of plastic. Care must be taken not to get the seed
mixed. Put one inch of unsifted compost into the pan. Then,
fill the pan up with a mixture of sifted compost and sharp
sand, gently pressing down the soil and leaving ½ inch
at the top of the pan. Place the dividing slips in the pan
and label all of the sown seeds with the date. Do not cover
the small seeds with potting mix but very gently give a sprinkling
of silver sand to anchor them. Large seeds should be pressed
gently into the soil.
After sowing the seeds, place the pans in a
container with water sufficient enough to reach about 2/3
of the way up. Once the top of the soil is visibly damp, the
seeds are ready to be put into the heated propagator-70 to
90 degrees at the end of January or early February. The base
of the propagator can be sand, but the spaces of the pans
can be filled with damp peat up to the rim. Place the cover
over and shade with dark paper. However if it is not possible
to maintain a temperature of around 70 degrees F, it is better
to wait until late April or early May, when general temperatures
should be much higher, before sowing. The initial watering
should be sufficient until some of the seeds are showing but
be sure to watch them carefully and water with a fine spray
Some varieties take longer than others, depending
on the species. However, some seedlings may show within 7
to 10 days while others will take much longer. Mammillarias
may be up in a fortnight or sooner. And, again, if the seed
is a mixture of varieties, a few will germinate much quicker
than others. It is really much better to sow each variety
separately. Opuntias, ferocactus and some types of cereus
can take a long while to germinate. It has been found that
large seeds will germinate more quickly if they are well washed
with hand-hot water before sowing.
Cover seeds after sowing. It is really a must
with most cacti seed. But whichever covering you choose--a
propagator of frame and glass over the boxes or pans-or even
polythene bags over the pans--it is very important to wipe
the coverings daily to remove any moisture that has formed,
as dripping moisture will rot the seed or seedlings.
As soon as the seedlings appear, the paper
or covering must be removed to allow for light. But, if they
are exposed to too much bright sunlight, they can turn red
in color and may stop growing for a long while. Once the seedlings
germinate, raise either the glass or frame cover daily so
they can get light and air. Otherwise, the seedlings will
The disease called "damping-off"
is a very troublesome enemy of tiny seedlings. It is, therefore,
very important that the seed compost is correctly sterilized
and pure clean water is used for spraying and watering. Once
seedlings are attacked, they are sure to die. If mildew forms
on the surface of the pans, it could be caused by some seed
pod husk when sowing the seed. It is very important to see
the seed is free of all impurities.
Do not let the pans dry out while germination
is taking place. Once the seedlings are up, it is then much
safer to allow pans to become almost dry before applying any
It is also important to prick out the seedlings
as soon as they are ready. If left too long in the seed pans,
they may stop growing. Once this happens, it can be a long
time before they begin growing again, and very rarely make
The seedlings should be ready for pricking
out when they are about 3 months old, but some varieties may
have to be left much longer. The best time to transplant is
after the cotyledon (first seed leaf) has been absorbed by
the plant proper. You will find that the seedling will have
a good root system and can be potted without damage. The seedlings
are best planted about one inch apart in good, strong trays
which have been washed with disinfectant to prevent any diseases
from occurring. Potting mix can be used but add about one
part of sharp sand to every 5 parts of compost by volume to
make it more porous. Level off the soil around the plants
and firm gently.
When removing seedlings from the seed pan,
it may be possible to raise all of the seedlings together
and then gently separate the roots. Make sure the roots go
well into the soil and try to spread them out. Label each
kind of seedling with its name and the date when it was potted.
Then, water very carefully. The seedlings must be kept in
a shady place. Under no circumstances should they be placed
in the sun. It is also important not to apply too much water
until the seedlings start to grow again after transplanting.
The temperature still needs to be near 70 degrees
F. If the temperature drops during the night, it should not
hurt the seedlings as long as it does not go below 50 degrees
Water the plants so the soil is quite damp.
Then, do not water again until the soil shows signs of drying
out. Make sure there is plenty of circulating air during the
day, but close the ventilators fairly early in the evening.
The primary reason why seeds do not germinate
is that they have been sown too deeply. Also, stale seed often
has a very small chance of germinating, especially if it has
been kept in poor conditions. Use fresh seed and buy from
a reputable company. Do not expose seed pans to strong sun
and be sure to bring them into light as soon as they are up.
Be patient and don't be too quick to pot up
small seedlings. Leave them in the pricking-out boxes until
they are touching one another. At the first potting, the seedlings
should be put into 2 or 2 ½ inch pots, depending on
the variety or species. Some seedlings, such as mammilarias,
may even flower in their seed boxes or pans following the
year of sowing, but other flowering cacti, such as rebutias,
notocactus, gymnocalycium, lobivias etc., generally take 2
Years. Others, such as opuntias, cereus and ferocactus, may
take much longer.
After the plants are potted up and growing
well, with a few exceptions, they should be able to stand
a winter temperature of 45 degrees F, so long as they are
A weak solution of liquid fertilizer can be
used about once a month during spring and summer on most varieties
The cactus family extends to many thousands
of varieties and species. We have only covered a small number,
but the basic instructions will apply to raising practically
all of the varieties.
An exception may be the following epiphytes
that grow naturally on trees. They require slightly different
growing instructions, especially as they flower from Christmas
Examples include Zygocactus truncatus, Schlumbergera
bridgesii (Christmas Cactus), Schlumbergera gaertneri (Easter
Cactus) and Rhipsalidopsis rosea (Whitsum Cactus). All of
these types require low to medium light, porous yet moisture-retentive
compost, and a need for watering when the soil becomes dry.
They should be kept drier in autumn to encourage bud formation.
They need a humid atmosphere and from spring to late August
will benefit from a weekly misting. Just as the buds begin
to form, place the plants in a cool place where, as long as
the temperature does not drop below 45 to 50 degrees F, they
can be kept in darkness at least 12 hours each night.
Epiphyllums are different still, and require
full light from early autumn to spring, then partial shade
after flowering. They can be plunged outside in a shady position.
It is necessary to check all pots before bringing them in
to ensure that there are no worms in the pots. After flowering,
plants should be rested for 6 weeks when they will need only
enough moisture to prevent the soil from becoming completely
dry. At all other times, the compost should not be allowed
to become too dry. Water less frequently in late autumn and
winter. Overhead spraying is also beneficial, when they need
only enough moisture to prevent the soil from becoming completely
dry. Aporocactus (Rat's Tail Cactus) needs rich, open compost
and plenty of water in summer.
Care must be taken to ensure that the propagating
area is free from pests. Here are some to watch for:
Mealy Bug As hot and dry as the summers in
Texas are, some people wonder if there is anything that is
really easy to grow during the dog days of June through September.
For those of you who want to grow a low maintenance plant,
you may want to consider cactus.