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not reflect current scientific knowledge
or recommendations. These texts
represent the historic publishing
record of the Institute for Food and
Agricultural Sciences and should be
used only to trace the historic work of
the Institute and its staff. Current IFAS
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site maintained by the Florida
Cooperative Extension Service.
Copyright 2005, Board of Trustees, University
for lhC aloridd LRndU CB
B. Tjia and R. J. Black
CANNAS FOR THE FLORIDA LANDSCAPE
B. Tjia and R.J. Black
Department of Ornamental Horticulture
University of Florida, Gainesville
Cannas belong to the Cannaecae family and have leaves resembling those of the
banana. They are tropical and sub-tropical perennials which flower twelve months
of the year in their native habitat. Present-day cannas have descended from the
old-fashioned Indian Shot, Canna indica. In tropical and subtropical areas they
range from 2.5 feet (75 cm) to 10 feet (300 cm) in height. In temperate regions,
where they are handled as tender annuals, cannas rarely exceed 4 feet (120 cm) to 6
feet (180 cm) in height.
Cannas are valued mostly for their large tropical foliage and showy,
brilliantly-colored flowers. The foliage is as ornamental as the flowers. It may be
pure green, greenish blue, coppery to purplish, ruby, or green with white stripes.
Cannas of today bear little resemblance to their ancestors. Their large flowers are
available in such colors as ivory, yellow, rose, salmon, crimson and red. Many of
their growth characteristics also have been modified to make cannas more suitable
for landscape planting. There are dwarf cultivars now that grow to only 1.8 feet (45
cm) in height and tall ones that attain a height of 6 feet (180 cm) as well as
Regretfully, cannas are not widely used by homeowners. Traditionally they have
been used in borders, where their colorful foliage provided interesting background
material. They have been grown in masses mostly in formal or informal beds and
borders, circles and squares in the center of lawns and gardens, public places, parks
and gasoline stations. Cannas should be seriously considered for planting in the
home landscape. They are not hard to grow and the rhizomes (fleshy, underground
rootlike structures) can be easily grown year-round in south Florida and most of
the year in north Florida.
Care and Culture
Cannas thrive best in well-drained, loamy soil rich in organic matter and
containing an abundant supply of nutrients. The incorporation of one to two inches
of well-rotted manure will help improve the soil in new flower beds. However,
cannas will grow in almost any soil, provided good fertilization and irrigation
practices are followed religiously.
Cannas are essentially sun plants and will perform well if grown under full sun or
The rhizomes may be planted 1 foot (.30 m) to 1.8 feet (.45 m) apart, depending
upon whether dwarf or tall cultivars are used, two weeks before the last frost in
early spring in north Florida.
Rhizomes may also be potted in small pots or wooden flats containing moist peat
moss in early February to allow roots and shoots to grow and develop. These are
then transplanted into beds after all danger of frost is past. Transplants handled in
this manner will flower earlier than those from rhizomes that are transplanted
directly into the beds. Adding 1/3 cup of fertilizer such as 10-10-10 and mixing it
in with the soil for each rhizome will assure fast-growing specimens.
To assure continuous bloom throughout the summer, remove the part of the
stem that bore flowers after the flowers have withered (Figure 1). Usually a second
flowering shoot, growing from the node just below the terminal flower, will be
halfway in bloom already. Remove this shoot also when its blooms are withered.
Another flowering shoot will soon develop on the node below the second shoot.
If the first and second shoots are not removed, all the nutrition will be used for
the developing seed pods and the flower cluster on the third node usually will
remain dormant. If spent shoots are removed, the nutrition will be channeled to the
young flower clusters on the third or fourth node to develop and bloom. If the
removal of spent shoots is followed religiously, cannas will bloom profusely for a
long period of time. Finally, when all flowering shoots finish blooming, remove the
entire stem and leaves at or slightly above ground level, since no more flowers will
grow from these stems. This will reduce the leafy appearance and will permit more
light for other developing and flower-bearing stems on the same clump. In addition,
this will reduce crowding and competition for nutrients.
Cannas thrive under high summer temperatures. The only limiting factor in their
growth at this time usually is lack of adequate moisture and fertilizer. If it doesn't
rain, water them generously twice a week.
Cannas respond favorably to high fertility levels. Fertilize them early in the
spring and continue on a monthly basis to assure prolific blooming.
The rate of fertilizer application is based on the nitrogen that is present in the
fertilizer formulation. Generally, for a fertilizer which contains 5 percent nitrogen
the recommended rate is 2 Ibs (908 g) for each 100 sq ft (9.3 m2). When a fertilizer
containing 10 percent nitrogen is used instead, since it is twice as concentrated as
the 5 percent formulation, the rate of application should be 1 Ib (454 g) per 100 sq
ft (9.3 m2) to give the equivalent of 2 Ibs per 100 sq ft for the 5 percent containing
If a 20 percent formulation is used, obviously the rate used should be 1/2 Ib (227
g) per 100 sq ft.
If you know how much to apply, based on the nitrogen percentage, you can use
many kinds of fertilizer without dependence on only one formulation of fertilizer
that may not always be available in your locality.
In areas where the soil is thin marly materials overlying limestone as in Dade and
Monroe County, cannas can still be grown successfully. In fact most tropical plants
can be grown in these areas without too much dependence on the existing sand or
In areas such as these, cannas can be planted and grown in inexpensive plastic 4
Figure 1. Flower Trusses of Canna. When the terminal truss (shoot) finishes blooming, do not
allow it to set seeds. Remove the terminal shoot promptly.
to 5 gallon nursery pots filled with good organic soil. The pots should then be
spaced and buried in the ground. The exposed top and sides are then covered with
mulch such as grass clippings or seaweed. No one will ever know that the plants are
growing in pots. Growing cannas in this way saves the expense of adding truckloads
of soil to flower beds. Obtaining a small amount of good soil amended with
adequate fertilizer to fill the pots certainly is a better and less laborious method.
Growing them in pots confines the root system in which fertility levels can be
The beneficial effects of growing cannas in pots are as follows: (1) Less fertilizer
is used although fertilization frequency may be increased; (2) no pollution will
result, since leaching of fertilizers is virtually nil; (3) reduced problems with
soil-borne insects and nematodes; (4) less watering since a good organic soil medium
will hold more moisture than marl or sandy soils; (5) growth of excellent flowers
where commonly inferior plants have grown, especially around shrubbery and trees;
(6) reduced expenses since a good soil medium can be reused year after year; and
(7) keep your neighbors wondering why you have such a magical green thumb.
When cannas are grown in pots the fertilizer used should be one-fourth the rate
recommended for plants grown in ground beds. For instance, when a 5 percent
nitrogen-containing fertilizer is used, the rate for 100 sq ft (9.3 m2) should be 1/2
Ib (227 g), and this amount should be divided equally among the number of pots
occupying 100 sq ft of area.
As mentioned previously, the root system is somewhat restricted for pot grown
plants. For this reason the rate of fertilizer should be further reduced to half the
recommended rate for soil grown plants, but the frequency of fertilizer application
increased, such as biweekly rather than monthly. Thus 1/4 Ib (114 g) of 5 percent
nitrogen-containing fertilizer applied biweekly should give the homeowner the best
In milder climates such as southern Florida where heavy frost is seldom
encountered, propagation is either by seed or division before planting. Seeds can
also be used in northern Florida, usually planted in early January or February.
Since the seed has a tough seed coat, steeping the seeds for 24 hours in warm water
and notching the seeds before soaking will insure a better germination percentage.
Seeds germinate at 750F (27C) and, if started early in the greenhouse or house,
will flower in the same summer.
In areas where hard freezes are uncommon as in southern Florida and the Keys,
overwintering cannas is not necessary. However, it is a must to dig the clumps each
year to rejuvenate plants and assure prolific growth and showy specimens for next
year. In the tropics cannas are grown in the same spot year after year. But
overcrowding, allowing the plants to set seed, and not removing the old stems,
causes the appearance to diminish after the first year.
Overcrowding or failure to rejuvenate the bed will result in fewer blooms, poor
nutrition and the development of deficiency symptoms. Deficiency symptoms
occur readily in the sandy soils of Florida.
Regardless of whether cannas are planted in flower beds or pots, the clumps need
to be dug on an annual basis, cleaned and old rhizomes removed and discarded
(Figure 2). Spade up the entire clump or remove from pots and divide each clump.
Discard those that are old and do not contain meristematic tissue (eyes). The
selected rhizomes should be cleaned off and rinsed in a chlorox solution (1 part
chlorox and 9 parts water) to reduce the possibility of disease that may infect the
rhizomes. Cleaned rhizomes can be transplanted or repotted right away.
For northern and central Florida, rhizomes should be spread out in a cool place,
such as a garage, to dry for a week or so. When the cut ends are dry, remove all the
dried roots and place the rhizomes in a flat or box. Cover with dry peat moss and
store in a cool place in the garage. Refrigeration of the rhizomes is not
Figure 2. Steps to store and plant Cannas: I. Remove growth above ground one or two weeks
after first killing frost for north Florida and anytime for south Florida. II. Dig around clumps.
III. Remove sand and organic matter from rhizomes. IV. Separate rhizomes. V. Cut off all of
the remaining stem. VI. Allow rhizomes to air in the sun or garage (700F) to dry freshly cut
surfaces. VII Layer rhizomes with peat moss and store in dry, well ventilated garage.
VIII. Plant in flats or pots one month before last frost. IX. Transplant in the garden after all
danger of frost is over (March 15 for northern Florida).
recommended since the rhizomes deteriorate when at a temperature of 450F (70C)
To avoid excessive drying of the rhizomes, it is customary to cover the flat or
box with a layer of clear plastic or a plastic bag. If this is done, be sure to make a
few holes in the bag to allow some exchange of air for rhizome respiration.
Otherwise, the rhizomes, which are live respiring tissue, will be depleted of oxygen
and will undergo a fermentation process.
In the spring, 2 weeks before the last frost, the rhizomes can be transplanted
outdoors. They may also be transplanted into clay pots or trays somewhat earlier
and kept moist. Placing them in a south window so they receive maximum light will
insure rapid growth of both roots and stem.
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Figure 3. Gladiolus Flowering Canna
Figure 4. Orchid Flowering Canna \.
Cannas do well in full sun, and keeping the growing shoot as close to the window
as possible where maximum light intensities will prevail is a must to prevent weak
and spindly growth. Transplanting an already actively-growing specimen outdoors
after danger of frost is past will insure earlier bloom in mid April or early May.
The storing of canna rhizomes for next season's growth is a common practice.
However, cannas are tender perennials and are everblooming. No amount of storage,
dormancy, or rest period is actually necessary for next season's growth. What this
means is that when a growing facility such as a hobby greenhouse is available,
cannas can be overwintered in pots and allowed to grow during the winter season.
Properly cared for, they will continue to grow and bear flowers in the middle of
winter. When the winter season is over they can be divided with the stems left
intact and transplanted directly in flower beds in late spring.
The cannas used in gardens today are mostly Canna generals, not the Indian
Shot, Canna indica. Today's cannas have two basic kinds of flower forms. Those
flower spikes that are arranged close together on the stalk and have wide petals are
often known as the gladiolus flowering cannas (Figure 3). Flowers that are arranged
somewhat loosely, with narrow petals, are called the orchid flowering cannas
Cannas are classified according to their height at maturity. They are divided into
three distinct groups.
Group I-Very Tall Growing
Very tall growing cannas (also known as the "giant cannas"), require some room
to grow and display their flowers and foliage. Space them 2 feet (60 cm) apart.
Among the oldest choices that are still popular are:
Red King Hubert
Yellow King Hubert
Mrs. Alfred F. Conrad
City of Portland
red with dark border
The newer cultivars introduced in the '50's belong to the "opera series." These
cannas are exceptionally uniform in height, 4 feet (120 cm), bear very large spikes
of huge satiny flowers, and all possess green foliage. Their cultivar names are all
Group II-Low Growing
The latest and most useful introductions and also the most expensive come from
the famous Pfitzer Nursery in Stuttgart, Germany. These cannas never exceed 36
inches (90 cm) tall in open gardens, and 24 inches (50 cm) in containers. They are
perfectly suited to small gardens, apartments, terraces, roof gardens or any other
area with limited space. They grow very well in tubs on porches and patios. The
leaves are all green and the flower spikes are large with well proportioned flowers.
The colors are unusual and the cultivars bear descriptive names.
CULTIVARS FLOWER COLOR
Rosen Kavalier coral rose
Stadt Fellbach gold orange
Shell pink pink
Cherry red red
Procelain rose rose
Primrose yellow yellow
Chinese coral coral
Scarlet beauty scarlet
Salmon pink s. pink
Tiger lily yellow petals
splotched with red
The dwarf cannas are usually restricted in their use to borders, accents in front of
shrubs, or in beds with mixed annuals and perennials. They grow 16 inches (40 cm)
to 18 incher (45 cm) tall. All have green foliage and "Dwarf" names.
CULTIVAR FLOWER COLOR
Doc deep red
Grumpy rose red
Seven Dwarfs mixed
mixed (rose, red, orange
yellow and salmon)
Cannas generally do not have the many problems so common to other annuals or
perennials. Canna leaves are covered with a waxy substance that repels water. It is
for this reason that diseases on cannas cannot establish themselves even though the
relative humidity is high and rain fall very high. Diseases develop on occasion and
these are usually restricted to dead tissues where flowers have withered and allowed
to remain on the flower stalk (Botrytis sp.). The removal of spent flowers
consequently will remove the disease organism.
The most troublesome insects that infest cannas are grasshoppers and caterpillars.
Results of heavy infestations will render the canna worthless as an ornamental plant
(Figure 5). Caterpillars will infest the young uncurling growing points and chew
Figure 5. Canna leaves showing the result of infestation by chewing insects. Ragged leaf edges,
holes straight across the leaf blade or a straight cut across the middle of leaf blades are typical
symptoms of caterpillars and other chewing insects. Problems such as these will develop rapidly
on cannas and render the plant useless as an ornamental, or at least reduce their aesthetic
appeal. Insecticides to control these pests should be applied as a preventive measure on a regular
basis or when the first signs of insect infestation appear, before much damage or severe
infestation has occurred.
through them. Small holes straight across the developing leaf blade is a sure sign of
caterpillar infestation and in severe infestations half of the leaf blade may
disappear. Observing plants carefully for chewing insects followed by the
application of the appropriate insecticide at once will insure beautiful plants all
Another problem frequently mistaken as insect damage is parallel tears in the
leaves (Figure 6). When examined closely, the insects are nowhere to be seen and
there is the absence of droppings, so typical of insect infestation. This problem is
not caused by insects but by water stress followed by an abundance of water. Once
this happens there is not much that can be done. The problem, however, can be
prevented by periodically supplying water during dry spells.
Figure 6. Splitting of the leaves is a problem resulting from water stress produced by long
periods of dry weather, followed by a heavy rain. The available water will cause rapid expansion
of young cells close to the stem and base of developing leaves. The distal end of the same leaves,
which consist of older cells, is not expanding as rapidly and this causes differential growth rates
on both ends. This results in the constriction of growth (above). The problem will develop
further as the leaves begin to expand and open, resulting in tears parallel to the venation of leaf
blades which is commonly mistaken for infestation of chewing insects.
This publication was promulgated at a cost of
$441.60, or 8.8 cents per copy, to assist home-
owners in Florida.
Single copies are free to residents of Florida and may be obtained
from the County Extension Office. Bulk rates are available upon
request. Please submit details of the request to C.M. Hinton, Publi-
cation Distribution Center, IFAS Building 664, University of
Florida, Gainesville, Florida 32611.
COOPERATIVE EXTENSION WORK IN AGRICULTURE AND HOME ECONOMICS
(Acts of May 8 and June 30, 1914)
Cooperative Extension Service, IFAS, University of Florida
and United States Department of Agriculture, Cooperating
K. R. Tefertiller, Director