Excerp from "Watergardening.com"
about water Cannas
Once considered stodgy plants that only grandma would grow, cannas
have made a colorful
comeback
in the perennial border. Now water-loving and water-tolerant cannas are
making a bold
statement
in the water garden landscape, too. Blooming far longer than their terrestrial
cousins,
water
cannas light up the pond from early summer through fall.
Cannas
that are suitable for the water garden may be very generally separated
into two broad
categories.
True water cannas, including those called the Longwood hybrids, grow well
in saturated soil
with water
over their crowns. Water-tolerant cannas, on the other hand, have adapted
to wet conditions
but grow
well in average soil as well. Unfortunately, there is no easy way to determine
whether a
land-based
canna will grow in the pond. Trial and error appears to be the only method
to find out if a
particular
cultivar is suitable for the water garden. For the sake of simplicity,
we'll group both types of
cannas
under the general heading of "water cannas."
True Water
Cannas
Cannas
that are truly adapted to water include Canna flaccida, Canna glauca, and
their hybrids. The
first,
C. flaccida, is native to Florida and is commonly known as Florida Water
Canna. This species
canna
has clear yellow flowers with a shape reminiscent of daffodils. Blooms
appear most heavily in the
spring
and then sporadically through the summer. Usually reaching a height of
about 4 feet, Florida
Water
Canna has a narrow spread and attractive, medium green foliage. It grows
readily with its crown
submerged
as far as 10 inches below the water surface.
Canna glauca
is native to South America. Its native range now covers most of the southeastern
United
States,
and it is not uncommon to see it growing along waterways in Georgia, Alabama,
Florida, and
Louisiana.
It also has yellow flowers and can grow up to 6 feet or more. It, too,
enjoys several inches of
water
over the crown.
The famed
Longwood Cannas are the direct offspring of Canna glauca. In the early
1970's, Dr. Robert
Armstrong
crossed Canna glauca with terrestrial canna hybrids. These offspring are
identifiable because
of their
blue-green foliage, for which Canna glauca itself was named. Although one
of their parents grew
only on
land, Longwood hybrids are just as water-tolerant as Canna glauca. All
of the Longwood Cannas
will grow
easily in water that is several inches deep.
Longwood
hybrid cannas usually grow anywhere from 2 to 6 feet tall in our northern
Indiana garden,
depending
on cultivar, and have a narrow spread of 2 or 3 feet. Their flowers are
commonly referred to as
‘plumeria
type' because the petals are thinner and more recurved.
‘Ra' is
the tallest of the Longwood hybrids, reaching to about 6 feet with bright
yellow flowers the color of
buttered
sunshine. ‘Endeavor' is slightly shorter, approximately 5 to 6 feet or
so, and is distinguished by
its butterfly-like
flowers that are a saucy, bright red. Slightly smaller is ‘Taney,' which
has intense
orange
blooms. The smallest of the Longwood hybrids is ‘Erebus,' which grows to
about 3 feet and has
soft,
delicate, peach blooms that approach the color of salmon.
Terrestrial
Cannas That Tolerate Water
Cannas
that are truly land-loving but have adapted to wet soil are becoming more
readily available. Each
of these
selections grows best in either very moist soil at the edge of the pond.
Some will tolerate just a
slight
amount of water over their crown.
One better-known
favorite that has made the transition from land to pond-edge is ‘Florence
Vaughn.'
This cultivar
reaches 4 to 5 feet and has giant flowers that look like orange gladiolus
edged in yellow.
Two other
terrestrial types that are suited to the water garden have been developed
and hybridized by
Herb Kelly,
a well known canna breeder in Sanger, California. ‘Intrigue' has pink-orange
plumeria-type
flowers
accented by dark purple foliage. A tall canna, it can reach from 6 to 10
feet in height. ‘Panache'
has delicate,
vanilla-cream plumeria-type blossoms that are marked by raspberry in the
center. It grows
shorter,
to about 5 or 6 feet tall.
Some water-adapted
cannas are as highly regarded for their flamboyant, variegated foliage
as they are
for their
flower. ‘Pretoria' has boldly-striped leaves that resemble bananas. The
foliage is bright green
streaked
in yellow. As if that weren't enough, the canna bursts forth with large,
mandarin-orange
gladiola-type
flowers that float 5 to 8 feet above the ground. A closely related cultivar
is ‘Striped Beauty'
(also
known as ‘Bengal Tiger') which has yellow and white gladiola-type flowers
and foliage streaked in
yellow
and red. It, too, can reach almost 8 feet in height. Because the foliage
of these cultivars is so
intense,
some gardeners find the blooms so gaudy that they cut the flower stems
before the buds have
a chance
to open.
Recent
introductions are even more stunning than ‘Striped Beauty' and ‘Pretoria.'
Consider ‘Durban' and
‘Phasion.'
Both have foliage heavily veined in gold and flushed in red, giving the
leaves a coppery and
almost
electric appearance. ‘Durban' has tomato-red gladiola-type flowers, while
those of ‘Phasion' are
more orange.
The two are easily and often confused, and in England, ‘Durban' and ‘Phasion'
are sold as
the same
cultivar. Each grows anywhere from 5 to 8 feet tall and performs best at
the very edge of the
pond in
soil that is constantly saturated. If you don't want red or orange flowers,
then choose the soft
hues of
‘Pink Sunburst.' It has yellow and green foliage that is flushed pink and
accented by pink
flowers.
‘Black Knight,' a terrestrial canna that adapts well to wet areas, has
purple leaves with green
stripes.
As if this weren't enough, it has large blooms that are swirled in orange,
yellow and red.
Planting
and Seasonal Care and Maintenance
All water
cannas are lovers of the tropics. They must be protected from frost and,
in colder climates,
may have
to be brought indoors to spend the winter months. They also grow best in
full sun, needing at
least
4 or 5 hours of sunlight in order to grow and flower well.
It's best
to grow water canna in a large, wide pot that is deep enough to act as
a sturdy base to prevent
the plant
from falling over in the wind. The rhizome of the canna can be planted
several inches below the
soil surface,
too, so that the plant has greater support from wind. Heavy clay soil is
the best potting
medium,
since sand can shift and cause the plant to topple over unexpectedly.
Cannas
are among the least fussy of water plants. In summer they benefit from
monthly doses of
fertilizer.
They look best if spent leaves and flowers are removed. To prompt the canna
to produce more
blooms,
cut off the top portion of the flower stalk once all the blossoms are spent.
In milder
climates where a heavy freeze is unlikely, water cannas will easily survive
the winter in the
pond.
In colder areas, the pots should be brought indoors when the winds grow
cold. Gradually dry
down the
soil and cut off dead foliage. Remove the pot and break away the soil and
you will find the
rhizome
that can remain dormant through the winter. Clean the rhizome so that it
is free of soil and
dead roots.
Store it in a ventilated plastic container of damp sand or peat moss until
the spring. When
warm weather
returns and the water temperature is consistently at approximately 65 degrees
F, plant
the rhizome
deep in a large, wide pot and return the plant to the pond.
Cannas
may also be overwintered indoors, by keeping them warm and giving them
plenty of water and
sunlight.
Their growth will slow and may be somewhat leggy, but come spring their
normal, healthy
green
color will return.
Diseases
and Insects
Only a
few pests affect water cannas. Aphids can sometimes appear, but they are
easily removed with
a stiff
spray of water. In heavier infestations, use an insecticidal soap recommended
for aphid control,
but make
sure to remove the canna from the pond before you begin treatment. Japanese
Beetles
sometimes
eat the foliage of our water cannas in mid- to late summer, giving the
leaves a lacy and
"skeletonized"
look. We take the beetles off by hand and throw them in the pond for the
fish to eat,
since
Japanese Beetles can't swim. Our biggest problem with cannas has been winter
attacks from
spider
mites or mealy bugs while the plants are overwintering indoors. Usually
we control the insects by
removing
the contaminated stalks to the base of the plant and throwing the stalks
away.
Canna rust
is another affliction that is not uncommon. You can tell a canna has rust
when you see
orange
spots on the leaves. Soon the plant will begin to wither and die. The disease
is easily
transmitted
on dead and dying foliage, and good sanitation is key. When we find a canna
infected with
rust,
we cut the stalks back to the crown of the plant (all the way to the soil
line), throw all the foliage
away,
and scrape a bit of the top soil off the pot just in case any small parts
of dead foliage fell into the
soil.
Care-free
and colorful, cannas are among the most valuable additions to the pond.
They are excellent in
container
water gardens either alone or combined with low-growing aquatics such as
Parrot Feather or
Bacopa.
Already popular in the perennial landscape, they are making a big splash
in water features as
well.
Latin Name Canna flaccida, Canna glauca, Canna x hybrids
Common Name Water Canna
Hardiness USDA Zones 7 (warmer with protection) to 11
Exposure Prefers full sun, grows in some shade
Cultivars
‘Black
Knight,' orange, red and yellow flowers, purple leaves with green stripes,
grows to 6 ft, water
depth
moist to 1"
‘Durban' bright red flowers with red/gold flushed foliage, grows 5 to 8 ft, water depth moist
‘Endeavor' (Longwood hybrid), red, grows to 5 ft, water depth moist to 6"
‘Erebus' (Longwood hybrid), peach, grows to 3 ft, water depth moist to 6"
‘Florence Vaughn,' orange and yellow, grows to 4 or 5 ft, water depth moist
‘Intrigue,' pink with purple foliage, grows 6 to 10 ft, water depth moist
‘Panache,' cream flowers with raspberry center, grows to 5 or 6 ft, water depth moist
‘Phasion'
(tm ‘Tropicanna'), orange flowers with red/gold flushed foliage, grows
5 to 8 ft, water depth
moist
‘Pink Sunburst,'
soft pink flowers, foliage with yellow stripes flushed in pink, grows 4
ft, water depth
moist
to 1"
‘Pretoria,' orange flowers with striped foliage, grows 5 to 8 ft, water depth moist to 1"
‘Ra' (Longwood hybrid), yellow, grows to 6 ft, water depth moist to 6"
‘Striped
Beauty' (aka ‘Bengal Tiger'), yellow and white flowers with striped foliage,
grows to 8 ft, water
depth
moist to 1"
‘Stuttgart,'
flowers open pale orange and mature to passion fruit orange, foliage heavily
streaked in
white,
grows to 7 ft, water depth moist to 1"
‘Taney' (Longwood hybrid), orange, grows to 4 ft, water depth moist to 6"
