Bananas are a versatile plant in any landscape, and add a lush, tropical look to any area. Although everyone knows the fruit, few people have experience growing edible varieties of the plant. Did you know that bananas can grow it regions other than the tropics? They are actually the world’s largest herb, a plant that goes on producing year after year.
Bananas, botanically in the Musa genus, are distantly related to ginger and heliconia. What looks like a trunk is actually a pseudostem, formed by leaves wrapping around each other, with new leaves arising from the centre as the plant grows. The true stem is underground. Bananas are fast growing, usually putting out one new leaf every week. Some form clumps by suckering and others remain solitary.
[Note that Ensete ventricosum, the false banana, is closely related and similar-looking plant but is grown for its decorative foliage, or its starchy rhizome, not its fruit]
Climate: bananas like a subtropical climate to do best, with high humidity (at least 50%) and temperatures around 25-30ºC (75-85º F). They will suffer in places with dry, hot summers, unless you’ve got some way of making a more humid microclimate. Wind can shred the leaves and make them look pretty ugly (as well as dessicate the plant), so if you’ve got room to plant several together, they can make their own sheltered microclimate. In cooler but humid climates, choose a sheltered, sunny spot, but in hot tropical areas you’d be better off growing them in some shade.
While it is possible to grow banana plants in cool temperate zones and have them produce fruit, unfortunately it is unlikely that the fruit will mature properly before cold weather sets in. Banana plants in cool temperate districts tend to produce a bunch in early summer which would have them ripen well into the cold weather period of mid-winter 6 months later. In the cooler climate of southern Victoria (for example Melbourne), with the shorter daylight hours and overnight temperature drops, maturation takes from 5 to 6 months or more (again depending on conditions).
Bananas can, however, be picked early and ripened by placing in a plastic bag with a couple ripening apples, although some say that because the fruit is not mature it lacks flavour and sweetness.
I’ve seen banana plants being coddled in the south of England at Great Dixter. (photo below). These plants are protected by a surrounding hedge, as well as a stack of hay which is held together by bamboo poles. Cavendish banana, Musa acuminata, is one of the best for cold climates and others like sugar banana, Musa paradisiaca, are a good all-round variety.
Planting: In Australia, before you plant a banana you need to check with your state government authority whether you need a planting permit as there are several banana protection areas through Queensland and NSW. It’s free, but absolutely necessary, even for one backyard plant in your home garden. This means that the source of any disease threats like devastating bunchy top (see Pests and Diseases below) which is spread by people planting infected suckers, or potentially weedy wild bananas can be quickly identified, which will help protect the country’s banana-growing industry.
Bananas are a BIG plant, up to 10m (33ft) so you need to make sure you’ve got plenty of room for the plant to grow and mature, and they’ll grow better if they’re away from trees with strongly competing root systems. They’re grown from a rhizome which you plant in rich, well-drained soil, covering the rhizome with only about 2cm (½ inch) of soil, or it will rot. You might buy a plant already in leaf – some people like to cut off those leaves and also trim back any roots to a 3-5 cm (2 inches). And no, you can’t grow bananas from seed, as only wild bananas have seeds.
Improve your soil with manure and compost so it both holds water but still drains well. Water the newly planted banana well, and make sure you keep it well-watered as it grows. Bananas need a lot of water!
Growth: The fleshy ‘stems’ sheathed with huge broad leaves can grow up to 10 metres (33ft) in as little as 1 year, depending on the variety and growing environment. Keep your plant well-watered and fed with a balanced fertiliser, although bananas do like lots of potassium as well. If the temperature drops too low (under 14ºC, or 55ºF), stop fertilising and watering. Keep the soil well-mulched. Each new leaf appears as a furled ‘cigar’ leaf, which takes about a week to unfurl. After the plant stops producing these cigar leaves, it is mature and ready to flower.
Flowering and Fruiting: After approximately six months, when the banana plant’s leaf formation is completed and the plant has matured, a flowering stalk grows up through the centre of the pseudostem and emerges from the top of the plant. This flowering stalk appears as a large, dark-purple bud and is called the bell. This is the male part of the flower. As the upper female part of the flower matures, the covering bracts curl back to show a developing ‘hand’ of bananas. Unusually, the fruit develops parthenocarpically, which means without fertilisation, or any seeds.
Some banana plants can produce up to 10 or so flowers and hands. As the hand grows, it can become very heavy (up to 40kg, or 90lbs) so you might need to prop or tie it up. In the subtropics it takes between 2 and 4 months for bananas to ripen (depending on variety, weather and other conditions). The hand turns upwards as the fruit grows.
Harvesting: Like most fruit, bananas that have been left to ripen on the plant taste the best and that way they will not all ripen at once. They will start ripening once the last bits of flower at the base of the banana rub off easily, or as the plant begins to die back. But watch out for banana thieves, like possums, rats and birds! And if the banana hand is in too much sun, it might also scorch on a hot day. You can cover it with shade cloth, or a coloured plastic bag which is what most commercial growers do.
Don’t forget to harvest your banana leaves as well, which make great wrappings for steaming fish and meat, or as a serving ‘plate’. You can also use the leaves and stems to make fibre and yarn.
Once your banana plant has gone through its fruiting cycle (after about 9-10 months), the mother plant will begin to die, leaving lots of banana plant ‘pups’ around the base. This group of plants all attached to the one rhizome is called the ‘stool’ or ‘mat’. Cut the dying leaves of the original plant back to the ground (you can spread them as mulch) and allow one or two suckers to grow up as your new banana plants.
Banana pests and diseases: apart from banana-thieving pests, bananas can suffer from wilts like Panama wilt, nematodes and viruses like bunchy top, which is widespread in south-east Asia and the Pacific but progressively being eradicated from Australia. You can help efforts to eradicate banana bunchy top by learning to recognise infected plants and quickly notifying authorities about any suspect plants.
There are hundreds of banana cultivars and many of the cultivar names are synonyms, which makes it very difficult to make a list, let alone recommendations. Cultivars can be diploid, triploid or tetraploid hybrids. If you want to delve into all things banana, look at the ProMusa website which is trying to build a stable list of banana cultivar names.
[Note that local quarantine restrictions may only allow you to grow certain cultivars in your area. Check with your local government authority.]
Cavendish: the most common fruit banana. You can also get Dwarf Cavendish which only grows to about 5m (16ft)
Lady Finger: smaller, straighter and sweeter fruit that does not brown when it’s cut.
Red Dacca: red banana with orange flesh
Ducasse: often called a ‘sugar banana’. Must be ripened fully (completely yellow) before eating. Good for tropical zones as it’s more resistant to fungal diseases.
Senoritas: a small, round tropical banana with light orange flesh.
Plantains: although this is the most commonly grown banana in the world, it’s not good eating, being very starchy, so they are used mainly in cooking.
Other varieties include Pisang Celan, Blue Java and Bluggoe (a plantain variety).