Outdoor Tropicals for Alabama

The concept of growing tropicals outdoors never grew beyond a handful of collectors, until the
realization was made that references to hardiness that were made in England had no relevance
to hardiness in the southeastern United States. As it turned out, hardiness was greatly increased
with sugar production inside the plant, which in turn correlated to high summer temperatures.
Many "hardy tropicals" would die at 25-30 degrees, while the same plant would survive sub 0
temperatures in the southeastern US.

The myth was perpetuated by gardeners in Florida, who confused ground hardiness
temperatures with container hardiness temperatures. When these Florida growers would have a
sudden temperature drop to 20 degrees, many of these vigorously growing tropical would die
and hence the incorrect hardiness data. In our climate, where temperature cool slowly in the
fall, many of these plants actually have a dormancy mechanism that can be induced with gradual
temperature decreases.

As with all plants of marginal hardiness, these hardy tropical should be planted early in the
season. This will allow the plants to become well established and build sugar storage for the
upcoming winter dormant season. Tropical plants installed late in the season, may not survive.

Probably the most common hardy tropical in the area are canna lilies. Most cannas are reliably
hardy to 10 degrees, and should easily tolerate temperatures of 0F or slightly below with a
good mulch.

With so many cannas to choose from, I have opted to write about primarily those sporting
variegated foliage. There is an old canna, probably originating in India that is sold under a
variety of names including C. Minerva', C. Nirvana', C. Striped Beauty' and probably a few
other names that have cropped up recently. This canna has green leaves, highlighted with
whitish yellow contrasting veins. After it reaches 4' in height, the top of the stalks are covered
with beautiful slender reddish buds that open with large yellow flowers.

Other nice variegated foliage cannas are C. Pretoria' or C. Bengal Tiger' from South Africa.
This 1963 import into the US has similar colored leaves to C. Minerva', but with a dramatic
narrow red edge around the leaf. Also the flower color is bright orange.

The newest South African imports to the variegated foliage mix are C. Durban' a 4' tall clump
with purple leaves with red veins and scarlet red flowers. The other is C. Pink Sunburst', a 2.5'
vigorous dwarf with similar purple foliage with red veins, but topped with rich pink flowers, and
C. Phaison'( aka Tropicanna) a 7' tall canna again with purple foliage and red veins, but topped
with vivid bright orange flowers. There is a unique black foliage canna "australia" along with
many burgandy and red leaf cannas which are too many to list.

Probably the most unique of the new cannas is C. Stuttgart'. This foliage canna was found by
Bob Hayes of the Brooklyn Botanic garden in a botanical garden in Stuttgart Germany. This
canna has dusty green leaves with giant blotches of white in each leaf. Because this canna has
so much white, it will only prosper in light shade. The small butterscotch flowers pale in
comparison to the striking foliage.

Once thought to be cheap and gaudy, cannas are now finding their place again in summer
gardens, lending a lush, tropical look to decks and patios and serving as a stunning backdrop to
fussier summer annuals. They thrive in large tubs on the patio; are perfect tucked into the rocks
around your fishpond; and can fill those hot spaces where nothing else seems to thrive. If you
Cannas are those large, banana-leafed plants that swing into summer bearing huge floppy
flowers the color of lemon yellow, deep orange, sherbet pink and regal red - some dotted,
splattered and picoteed with contrasting colors. And the leaves, which most people remember
as being only green, are also now cloaked with colors: purple veined with yellow and orange;
cream and white streaks; a deep burgundy through and through. Sizes of cannas range from 3-
foot-tall "ground covers" to 16-foot giants.

Cannas look like gingers and bananas, with large leaves ending in a point. Their "stem" is not a
true stem, but tightly furled leave bases arising from knotty underground rhizomes. The flower
stem ascends through the center of this "stem."

The rhizomes grow year after year, with new plants growing from along their length, so canna
beds tend to get larger each year. Occasionally the patch needs to be carefully unearthed, the
rhizomes separated and even cut apart (leaving at least one growth bud on it), and replanted
about 3-4 inches deep and about a foot apart.

Cannas prefer protected sites. Windy spots will shred their leaves, which doesn't hurt the plant
but doesn't help their decorative value any. While they will grow in any well-drained soil, one
that retains some moisture is preferable to one that is too dry. If it doesn't rain for a week, be
sure to soak the roots. Several canna species are classified as bog plants, and need to be set in
the water at all times.

Cannas respond to fertilization with abundant foliage and strong blooming. Use an all-purpose
fertilizer (6-6-6 will do, as will any liquid fertilizer) when growth starts in the spring and continue
monthly during the peak growing season. Farther south, cannas live year-round; up here, they
stop growing in the fall and are cut back to several inches to overwinter under a warm mulch.
Stop feeding around September.

To assure continuous bloom throughout the summer, take these tips from the University of
Florida's Institute of Food and Agricultural Sciences Extension bulletin: "Remove the part of the
stem that bore flowers after the flowers have withered. 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. Yet 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."

The three main complaints with cannas are: rolled-up leaves, a series of small holes marching
across the leaf surface, and leaves shredded when they unfurl. The first two are insect-related;
the third is the weather.

Small leaf-roller caterpillars hide themselves in a portion of the leaf, and this makes them hard
to reach by predators as well as with pesticides. Using an insecticide with Bacillus thuringiensis
(Dipel or Thuricide) mixed with a spread-sticker such as soap will control some of the
caterpillars. Spray in the afternoon and after rain, so the pesticide will be fresh when they come
out in the evening to feed. The small holes are caused them the caterpillars munching while the
leaf is furled; when it opens, the holes are in a row.

The shredding of leaves is done by water stress. When it rains a lot after a drought, the leaf
grows more quickly than it uncurls, tearing the tissue.

Elephant ears are another plant that have just begun to be recognized as in our area. The typical
elephant ear with green foliage (Colocasia esculenta) has been hardy for Tuscaloosa gardeners
many years with it giant grey green leaves to 4' in length.

Colocasia fontanesii. This 7' giant held 3' long leaves atop wonderful jet black stems. Each leaf
was a glossy metallic green black. Like C. Illustris', C. fontanesii spread on top of the ground
thru thick rhizomes.The upright Elephant Ears, Alocasia macrorrhiza, is another hardy elephant
ear for Tuscaloosa gardeners and is becoming more common. Elephant Ears may be slow to
appear after winter dormancy usually late April or May in Tuscaloosa.

Other "tropicals" that have proved hardy include:Gingers( ginger lilies) :

Curcuma petiolata: medium to full sun gardens

Curcuma elata: medium to full sun gardens

Hedychium coronarium and other species: medium to full sun gardens.

Curcumas species grow to usually 1 to 3 feet tall while the Hedychium species grow up to 8
feet tall, usually in the range of 4 to 6 feet..

Other "tropicals" for Alabama include cast iron plant (Aspidistra elatior) and some bananas like
Musa basjoo prove hardy but die down to the ground unless the stem is protected.

Flowering maples, Abutilon species especially the newer hybrids, are rated cold hardy in
Tuscaloosa. Some Amorphophallus species(Voodoo Lily) are also rated cold hardy in our area
but may require special winter care.(turning the bulbs sides ways in fall and replanting so water
doesn't collect in the top and rotting them.)

Hibiscus that are hardy include Hibiscus coccineus(Red Texas Hibiscus), Hibiscus grandiflorus,
Hibiscus mutabilis and many hardy hybrids like H x 'Kopper King' many with beautiful foliage
as well. These hardy Hibiscus die down to the ground in winter but come back in spring
growing as tall as ten feet in summer. The Hibiscus commonly sold in garden center (Hibiscus
rosa-sinensis ) are not winter hardy in Tuscaloosa and will not come back after winter unless
over-wintered in your home. The New Zeland Flaxes, Phorium species, are rated hardy in
Tuscaloosa and are popular on the west coast.

There are a few Orchids from the orient that are hardy in this area and make good garden
plants.

Bletilla striata is an orchid from japan and China and is easy to grow. Treat them like you would
a hardy bulb. They do need half day of sun to bloom well. They do have a tendency to send up
bloom stalks before last frost so keep an eye on these. Rich soil (regular enriched potting soil)
is a must as is a winter mulch to keep them dormant until after frost. They are totaly hardy in
this area and relative inexpensive. Calanthes are another orchid group and this group has hardy
and tropical members. These reguire a shady spot like you'd grow a hosta. The hardy members
include Calanthe sieboldi,Calanthe discolor,bicolor and several hybrids. Many more are being
brought into horticulture in the United States from Japan, China and India. These also like a rich
soil enriched with manure and peat moss but well drained. These also may send up flower
stalks before our last frost so it is best to keep an eye on these as well. Most of the Calanthe
species are evergreen.(retain the leaves during winter) These two come as close to tropical
orchids as they come to be grown outside in tuscaloosa year round. They have nice foliage as
well but the flowers are small when compared to the tropical orchids.

Orelander,Nerium oleander, is a beautiful shrub I see growing around Tuscaloosa but it is a
very toxic one that can kill if any part is injested. It is rumored to have killed people who have
inhaled smoke from burning a patch of it in Florida.

There are many more that I may not be aware of or have failed to list in the realm of "hardy
tropicals" and many new ones coming into trade. I do not grow most of the ones listed but
relied on friends, customers and reasearch for my information.

Please note that some of the above listed "hardy" tropicals hardiness depend on microclimate,
sitting and being keep drier during the winter. A extremely harsh winter may kill some
completely. Most will survive but some may not. There is no guarantee that they can survive.
growing these type plants should be considered experimenting. Otherwise use other plants that
are proven hardy here. These type plants may also require extra attention to their cultral needs.

If they do die it may not be a hardiness issue but a cultral requirement issue. This also applies to
the hardy palms.

Hardy Palms for Tuscaloosa

Hardy palms are another area that is exploding in popularity. Without a doubt, the hardiest of
the palms available is the southeastern native needle palm, Rhapidophyllum hystrix. This
clumping palm to 8' tall is best know for its sharp needles around the base of the trunk that
protect the seed from predators. This Palm is reportedly hardy to New Jersey and southern
New England. There are growing Specimens in the University of Alabama's Aboretum just off
15th street by the golf course.These are in the wildflower garden area of the aboretum.

The Gulf Coast native scrub palm, (Sabal minor) is another candidate for area gardens.
Reliable in hardiness to 0F . While sabal minor is thought of as a non-trunked palm, this is not
quite true. In actuality, the trunk grows downward instead of up. If you have ever tried to dig a
scrub palm of any size, you will soon realize that it is nearly impossible due to the depth of the
trunk (up to 5' deep).

The hardiest of the trunked palms is the windmill palm (Trachycarpus fortunei). This Chinese
native can easily make a 30' specimen in this area. Hardiness is variable within seedlings, so be
sure to ask if the seed came from a hardy specimen. A hardy feather leaved palm I have
noticed growing around town is the pindo palm, Butia capitata, it is reportedly the hardiest
feather leaved plam.