Botanical Overview
The banana is the largest herbaceous (non-woody) flowering plant. The Musa genus,
part of the Banana family (Musaceae), has about 70 species. Just two species, Musa acuminata,
and its hybrids with Musa balbisiana, provide nearly all the world's edible bananas. Bananas
grown to be eaten raw, called dessert bananas, are either Musa acuminata cultivars or hybrids
of the two species.
Eighty percent of bananas grown in the world are cooking bananas, sometimes called
plantains, and are hybrids of M. acuminata and M. balbisiana. These have more starch, less of
a banana taste and aroma, and are grown to be cooked and eaten like potatoes. When harvested
green for cooking, they are lower in sugar than dessert bananas, but some cultivars can become
very sweet if allowed to fully ripen.
Behind apples, citrus and grapes, bananas are the fourth largest fruit crop in the world.
Because they are produced year-round without a season, they are a significant food source
world-wide during the off-season for other foods.
Description
Form: An herb composed of a fleshy underground rhizome with tubular
roots, numerous suckers (shoots, pups), and at least one main shoot called a pseudostem forming the trunk
of the fruiting, leafy part of the plant.
Lifespan: 15 years or more for the rhizome, 1-3 years for each
pseudostem, depending on cultivar.
Leaf retention: Evergreen in regions without freezes.
Growth rate: Rapid.
Mature Size:
6-25' high, often 12-16' high. In hot, dry climates, most bananas are 4-5' shorter than those grown in
the tropics because of lower rainfall and lower humidity.
Roots:
A large rhizome, sometimes called a corm because of its appearance, forms the base of the plant.
The rhizome produces feeder (fibrous) roots growing from multiple side nodes, typically
up to 1.5' deep and up to 10' horizontally, but can be much longer and deeper in loose, moist soil.
It also produces new rhizome extensions from its side, each of which produces a sucker that will
develop into a pseudostem. The entire plant, including green leafy parts and roots is called a mat.
The root system is the permanent part of the banana plant.
Stems:
The pseudostem, which functions as the trunk of the banana plant, is a cylinder of tightly bound,
concentric leaf stalks that arise directly from the underground rhizome. It is not woody and is not
a tree.
In the second part of the pseudostem's life, after 10-15 months, the rhizome sends a flowering,
true stem upward that pushes its way through the center of the pseudostem, possibly weakening the
pseudostem. After the true stem emerges from the top, and as developing fruit on the true stem become
larger, the pseudostem may droop and need support. Dwarf cultivars are less affected by drooping.
When the main pseudostem of a banana plant dies after fruiting, the next oldest sucker grows to
replace it. With most banana cultivars, many pseudostems will grow at the same time and form a colony
covering a small area. Having a large colony produces better growing environment for the plant,
however less energy is available for fruiting. If fruit is the primary purpose, no more than two
suckers should be allowed to grow alongside the pseudostem in dry climates, because low rainfall and
low humidity make it difficult for the roots to provide sufficient nourishment.
Normal suckers have narrow leaves with pointed tips and are called blade or sword suckers.
These have large rhizomes and develop normal leaves when they reach about 3' tall. Suckers with
wide leaves, known as water suckers, have small rhizomes, will not develop into a strong plant,
and should be removed and used as mulch.
Leaves:
Smooth, waxy, dark green, sometimes variegated with red, white or maroon splotches, up to 2' wide
by 9' long. The midrib may be green or red. Often the front and back of the leaf are different colors.
New leaves may change color as they age. Leaves emerge tightly curled, arranged in a spiral pattern
around the top of the pseudostem. As the visible, above-ground pseudostem grows higher, it unfurls
about one leaf per week.
Flowers:
The true stem in the center of the pseudostem produces separate clusters of male and female flowers
at its tip, with the male flower cluster at the end, and the female flower clusters further back.
Bloom:
For most banana species, the pseudostem must survive more than one year in order to flower. For this
reason, all edible banana plants, in freeze-prone regions, must have their pseudostem protected
during winter to produce flowers the following season. Bananas have no flowering season and may
attempt to flower any month of the year.
Self-fruitful:
Edible cultivars produce fruit automatically without pollination.
Years before fruiting:
Most pseudostems produce flowers and fruit in their second year.
Fruit:
Long, thin to thick skinned. The seeds are tiny, sterile, black dots in edible bananas. The fruit
develop in groups called "hands". Five to 20 hands form a bunch.
Months for fruit to ripen:
Bananas must mature on the stem before ripening. Plumping and rounding of the fruit indicates
maturity at which point the fruit can first be harvested. Depending on the cultivar, maturity
can take anywhere from 6 weeks to 11 months. Immature fruit will not mature or ripen properly
off the stem. Only plantains need to be harvested green. For home dessert bananas, fruit that
ripen on the stem, indicated by a color change, often have a superior flavor. Some cultivars,
such as blue java, should ripen fully on the stem when possible. Others should be harvested
part way through ripening. Mature fruit should be removed from the stem, however, if
temperatures will drop below 50-53°F, to prevent cold damage.
Storage after harvest:
If dessert bananas are green, place them in a fruit bowl to ripen at room temperature. Place the bowl
in the sun to ripen even faster. Never store bananas in the refrigerator; below 47°F the fruit
will decay from the inside and turn black. Plantains are cooked while green.
Edible Cultivars of Note
Bananas are best categorized by their genome. Musa acuminata varieties are genome AA, meaning they have
two chromosome sets of type A, one from each parent. Musa balbisiana varieties are genome BB. Hybrids will
have at least one chromosome set from both A and B. Some varieties are polyploidal, meaning they have
duplicate chromosome sets resulting in a genome with three or four sets. The cultivars below are identified
by their genome group in parenthesis.
= Easiest for beginners to grow.
= Best all-around banana for rapid maturity, productivity, and flavor.
Dwarf 'Apple' / 'Brazilian' / 'Manzano' (AB)
Grows 6-12' tall. USDA 8b-11. Hardy and easy to grow, it produces fruit that is 4-5” long, with a
very sweet, apple-like flavor. This variety may only be available full-size, 12-18' tall.
'Dwarf Cavendish' / 'Grande Naine' (AAA)
Grows 6-8' tall. USDA 9-11. This is the standard commercial banana found in grocery stores.
'Dwarf Gros Michel' (AAA)
Grows 5' tall in a large container. USDA 9-10. The original commercial banana, now an heirloom,
was discontinued because of tropical diseases now prevalent in its home territory. It has a better flavor
than the Cavendish banana.
'Dwarf Red' (AAA)
Grows 6-10' tall. USDA 10-11. The fruit turn "sunset" colors when ripening, from dark burgundy
to orange, yellow-green and muted colors in between, and have aromatic, peachy tasting, orange-colored
flesh. This is a strong, vigorous plant with red pseudostems; however, red bananas are less cold hardy
and take longer to mature and ripen. The skin will be almost black before the fruit are ripe.
'Dwarf Green' is a green foliage version.
'Rajapuri' (AAB)
Grows 6-8' tall. USDA 8b-11. This plant tolerates poor, dry soil, pH 6.1-7.8
(Slightly acidic to slightly alkaline), withstands neglect better than most varieties,
and is often used for landscaping. It is very wind hardy, with leaves up to 3' wide.
The fruit are medium-sized, with a very sweet flavor. It can be harvested 7-10 months
after blooming. This is the best plant for gardeners new to growing bananas. It may
choke* however, in cold temperatures, if feeder roots are cut, or with insufficient
water.
'Blue Java' / 'Ice Cream' (ABB)
Grows 12-20' tall. USDA 9-10. This plant has silver-green leaves and is more wind-hardy
(a strong, wide root system) than most, but may need propping up when fruiting. The fruit are
silvery-blue, ripening to pale yellow. Some find the flavor to resemble fragrant, sweet vanilla ice
cream. If it is not properly ripe, however, the taste is very tart. The fruit hands should be covered
to protect them from the sun in high temperatures. Its drawbacks are that it takes a long time to mature
and ripen and does not produce a large quantity of fruit. Consider growing Dwarf Namwah instead.
'Dwarf Namwah' (ABB)
Grows 6-11' tall. USDA 9b-11. Vigorous, drought resistant, wind resistant, and easy
to grow. The fruit grows 4-6" long in large bunches. It has a sweet flavor with vanilla
notes similar to 'Blue Java'. Fast growing roots allow this plant to establish itself
quickly. This is the most widely grown plant in the ABB group.
'Dwarf Orinoco' / 'Burro' (ABB)
Grows 6-8' tall. USDA 8-10. A very hardy, vigorous, shade tolerant plant often used for
landscaping. It has soft, medium-sized fruit with a tough central core and orange flesh.
It is usually harvested when green and used as a cooking banana. It can be eaten raw when very ripe.
When green, it is said to have lime and apple notes in its flavor and when fully ripe has faint
lemon undertones.
'California Gold' is a cold-hardy version (USDA 7-10).
'Goldfinger' / 'FHIA-01' (AAAB)
Grows 6-8' tall. USDA 9-11. A very disease resistant plant with high wind resistance and very
tolerant of cold temperatures once established. It reliably produces 55-80 pounds of fruit with
a sweet and tart apple flavor.
'Mona Lisa' / 'FHIA-02' (AAAA)
Grows 10-12' tall. USDA 9-11. A plant with resistance to Black Leaf Streak disease,
but will succumb to Fusarium wilt. It withstands strong winds and is tolerant of cold
temperatures once established. Forty-five pounds of fruit are produced with a mild, sweet flavor
similar to Cavendish.
'Sweetheart' / 'FHIA-03' (AABB)
Grows 10-12' tall. USDA 9b-11. A cultivar bred for home gardens to be tolerant of poor, dry soil
and wind, and very disease resistant. The roots on this cultivar grow more slowly than others,
resulting in less wind tolerance and slower flowering in the first two years. 'Sweetheart' is a green
cooking banana that can also be eaten when very ripe. The ripe flavor is mild and has been compared to
a soft 'Blue Java' banana. The fruit ripen quickly after harvest, so should they be picked one hand
at a time and the rest left on the stem. Never harvest the entire stem at once. It will produce 30-150
pounds of bananas a year.
Wildlife: Attracts birds, bats, insects and lizards.
Toxic / Danger: No. Watery banana sap can stain clothes.
Origin: Southeastern Asia. Cultivated for at least 7000 years.
Musa acuminata 'Cavendish': Flowering stem with bananas, and
male flower cluster enclosed in bracts, at tip. Seen from below.
Cultivation and Uses
USDA hardiness zones:
7b-10 to 10-15 depending on cultivar.
These temperature limits apply to a well-mulched root system, not the pseudostems which are damaged
or killed below 33°F. Bananas stop growing below 53°F and over 100°F. Their growth is
slowed over 80°F.
Chill hours:
None.
Heat tolerant:
No. Growth stops above 100°F.
Drought tolerant:
No. Most cultivars need consistently moist soil, especially in high temperatures, but a few, such
as Rajapuri, may be able to survive on less water.
Sun:
Part afternoon shade especially when temperatures are over 85°F. Newly planted suckers need
part shade until they have rooted sufficiently. Deep watered plants may be able to handle all
day full sun after the plant has been in the ground more than one year. Indoor plants do not
fruit when they receive insufficient sunlight.
Planting:
Plant in a wind-protected area that receives southern sun and afternoon shade. A 6-8' high wall or
walled garden is recommended. The root area should be in a sunny location.
Planting on top of a mound or in a raised garden bed provides better moisture control and also
helps flush salt out of the bed. Dig a garden trench 5' wide and 2' deep (or a raised bed 5' wide
and 2' high), allowing 8-10' of length for each banana plant (centered) to avoid root competition
for nutrients. For example, with three banana plants, the trench or bed should be 24-30' long.
It must drain moderately well, but does not have to be fast draining.
Plant well after the last frost date. Do not expose new plants to temperatures below 57°F which will
greatly slow their growth. Plant any time during the growing season up to 10 weeks prior to the average
first frost date.
Dwarf bananas do well in containers, but will need more careful watering and cold protection.
Soil:
Bananas like soil that is warm, moist, with a medium to high organic content, and slightly acidic.
Use a mix of one-half well composted animal (herbivore) manure and one-half native soil. Add
soil sulfur to provide long term acidity. Lava sand may provide additional nutrients.
Most bananas do best with a soil pH of 5.5 to 6.5, but will easily handle pH 5.0 to 7.0.
Some bananas, such as Rajapuri, accept a soil pH between 6.1 to 7.8, slightly acidic to slightly
alkaline.
Fertilize:
Bananas are heavy feeders with a strong need for potassium and nitrogen.
Fertilize monthly with organic fertilizer or compost, but only during the warm growing season and
do not fertilize while the plant is fruiting. Fertilizing during fruiting can cause the fruit to rot.
Overfertilizing can lead to problems with leaves not unfurling properly.
Banana plants are salt intolerant so chemical fertilizers should be avoided.
Water after becoming established:
Use basin irrigation or perform
deep watering every one or
two days during hot summer months (especially when temperatures are over 85°F).
Deep watering results in deeper roots that are protected from summer heat. Do not allow the soil
to become dry more than 1" below the surface. An automated irrigation system using a bubbler
would be appropriate. Do not get the base of the pseudostem wet during irrigation.
Banana plants need abundant water in hot months. In the winter, decrease watering to once a month,
taking rain into account. Overwatering in cold weather leads to root rot.
The most common causes of banana plant death are insufficient water in high temperatures and
overwatering in cold temperatures.
Mulch:
A thick layer of mulch will reduce soil moisture loss and protect from the extremes of heat and cold.
A thick layer of mulch when freezing temperatures are predicted is mandatory to protect roots.
Use dead banana leaves and stalks for mulch whenever possible.
Care of Pseudostems:
In regions with freezing winter temperatures, when freezing temperatures are predicted, pseudostems
grown for fruit that have not yet flowered must be protected. If growing in a large container,
the plant can be moved indoors. Growing in the ground: (1) mulch the root area well,
(2) cut off the pseudostem just below the leaves,
(3) position a cage made of chicken wire about 2.5' in diameter around the stem and fill it
with straw or shredded leaves,
(4) place a plastic pot filled with straw on top of the stem, and
(5) wrap the plant in cloth from top to bottom. Remove the protective insulation in the spring,
after the last freeze date, and after daytime temperatures stay above 50°F.
If a pseudostem is fruiting and the fruit have not matured before winter freezes are
predicted, cut the entire pseudostem off, take it inside, and place it in a bucket of water
to finish maturing and ripening. The root area of the outdoor plant can then be heavily mulched.
If a flowering pseudostem begins to droop, prop it at the top of the fruit to keep it from
falling over. Propping the middle of the pseudostem may cause the pseudostem to fold or break.
If it has fallen, leave it alone and the fruit will usually develop normally. Trying to right
a fallen stem may injure it more and harm fruit development.
*Choking is a problem experienced by some cultivars.
The flowers and fruit start growing in the pseudostem before the true stem exits the top.
Choking is caused by cold temperatures, insufficient or inconsistent water supply, and feeder
roots cut during sucker removal. Irrigation must be increased in very high temperatures.
Methods to prevent chocking include adding a high nitrogen fertilizer or a growth stimulant
during true stem growth.
Prune: Cut away yellow and brown leaves as needed.
Cut pseudostems that have borne fruit, and have no green leaves, nearly to the ground.
Cut winter-killed pseudostems nearly to the ground.
If you remove the male flower cluster at the tip of the flowering stem, leave at least
12" of stem beyond the nearest hand of fruit to avoid drying the fruit. On some cultivars,
the male flower cluster is removed to avoid pollen spread. Parts of the flower are also used
in cooking and salads.
Water suckers should be removed, taking the least amount of rhizome possible, and used as mulch.
These suckers are sometimes sold as "tiny bananas" that have only ornamental value.
At least one blade sucker must be kept in place to replace the pseudostem when it dies after
fruiting. Most blade suckers should be carefully removed, when they are 1-2' high,
with enough of the rhizome and feeder roots to be viably planted somewhere else. Do not allow more
than two suckers to grow next to the pseudostem. In hot, dry climates, there is not enough
rainfall and humidity for the root system to nourish the plant sufficiently.
Use a tool such as a digging bar with a 3" wide blade to sever the sucker from the pseudostem.
A standard width shovel will cut tubular feeder roots as well as the rhizome, harming both the
pseudostem and the sucker.
If the sucker is further than 1' away from the pseudostem, cut straight down to sever the
connection. If the separation is less than 1', dig a hole between them until the rhizome is
reached, then place the cutting tool half-way between them angled 30° toward the bottom
of the pseudostem and make the cut. Gently remove the shoot with its feeder roots intact from the
surrounding soil. There should be at least one feeder root attached to the bottom of the sucker.
Litter: Moderate.
Propagation:
Blade suckers; cutting the rhizome into sections, each of which has roots and a tiny sucker;
seed of ornamental cultivars.
Tissue culture is also used because it avoids the possibility of disease transmission.
Uses: Edible fruit, ornamental.
Comments
Dwarf banana cultivars need less water and are affected less by wind and drooping.
In a hot, dry climate, a dwarf cultivar is often the best choice.
Do you have additional information or a different experience for these plants that you would
like to share? Email info@GardenOracle.com. All contributions are welcome and appreciated.