cluster of bananas growing on tree

Intellectual property has the shelf life of a banana.

- Bill Gates

Bananas aren’t necessarily the first thing you think of when someone mentions New Zealand-grown fruit. Thanks to a group of dedicated growers in Northland, locally grown bananas, alongside several other tropical and subtropical fruits are set to become commonplace on our supermarket shelves. As a university student in Canterbury, weekend trips into the city often involved a trip to the Botanic Gardens and ultimately a detour through the tropical Cuningham House to linger in the sticky humidity and admire the banana plants – bonus points if they were fruiting. A few years later, I found myself on a charity quiz team, stumped by the first question – what is the world’s largest herb? You guessed it, the banana plant.

My own first encounter with bananas grown on Kiwi soil was back in 2016 at the New Zealand Tree Crops Association annual conference in Pukekohe. An enormous stem of bananas was up for auction and I was sorely tempted. I imagined, with great glee, stuffing said gargantuan heap of fruit into the overhead locker on my flight home. Alas, practicality took over and I had to let them go. But this year, at the same conference in Ōtaki, my wish came true. Once again, I clapped eyes on some banana bounty and knew I wasn’t going home without them. Some steely-eyed bidding ensued – success! After negotiations with friends going on the ferry, those bananas were South Island bound. If you ever have the chance to purchase local bananas at a market in the North Island, I highly recommend it, although the experience will spoil you for good, as an imported supermarket banana will never cut it for you again. As an aside, the earliest reports of banana plants in New Zealand are from about 1890.

Bananas: a short family history

Bananas belong to the Musaceae, a family which consists of large herbaceous, monocotyledonous plants which grow from underground rhizomes. Their structure is composed of large leaves with overlapping fleshy sheaths at the base, which form a sort of false stem and gives some family members a tree-like appearance. Native to the tropical regions of Africa, Asia and Australasia, the Musaceae includes not only the banana species we cultivate commercially, but several popular ornamental species such as the bird of paradise flower, Strelitzia spp. and the traveller’s palm, Ravenala spp.

Bananas and their starchier cousins, the plantains, belong to the genus Musa within this family. Of the roughly 300 Musa species, only 20 are cultivated commercially. New Zealand imports 72,000 tonnes of bananas every year from the Philippines and Ecuador. Most of these are the Cavendish variety, which have thick skins suitable for withstanding the long sea journey. They are picked green, fumigated on arrival and then artificially ripened with ethylene gas. I kid you not, I once saw a classified ad in the situations vacant section of the newspaper for an ‘assistant banana ripener’. Not the actual ripener, but an assistant. This should give you some idea of the scale involved with bringing the world’s favourite fruit to market.

There is evidence of banana domestication stemming back some 7,000 years. Like citrus fruit, bananas have a somewhat muddled genetic history, and like anything humans have had a hand in, this tremendous genetic diversity has been funnelled down into a largely standardised single commercial variety. The genus Musa is evolutionarily ‘young’, and most commercial banana species are hybrids of the wild Musa acuminata, which is edible, and Musa balbisiana, which is seedy and inedible, but confers the handy characteristics of disease resistance and hardiness. Up until the 1940s, bananas were given binomial names, like Musa cavendishii, and treated as individual species. It soon became apparent that due to the extent of hybridisation, mutation and human selection tangled in the banana’s family tree, assigning species names to a set of diverse, asexual hybrids was not the best system. These days, bananas are given cultivar names. As you’ve probably noticed, supermarket bananas don’t have seeds – they are parthenocarpic, setting fruit without fertilisation taking place, and are therefore sterile, with most plants produced clonally, via vegetative methods. Somewhat surprisingly, China and India head global production of bananas, followed closely by the Philippines and Ecuador. If you’ve kept up with the news of late, you may have read about the terrible situation Ecuadorian banana growers are facing, with increasing pressure from drug cartels using banana shipments as a trafficking vehicle.

Suitable climates and growing conditions

Essentially a tropical to subtropical plant, and as such frost-tender, bananas can nonetheless be grown (and do successfully produce fruit) in temperate climates. With adequate protection from wind and sufficient heat units, they will grow well in the warmer areas of the North Island and certain microclimates in the upper South Island, e.g. Nelson-Tasman and potentially the West Coast. Growing under cover will definitely help extend the scope for cultivation. Dwarf varieties could be trialled in large pots with adequate fertile growing medium, but may need regular repotting as the plant grows in size. Ornamental varieties and the starchier cooking varieties (plantains) are more cold-tolerant than dessert fruit, so these might be an option further south with protection.

Depending on cultivar, bananas need between two to four metres of space between plants - being shallow rooted, they do not like competition in the root zone. Be prepared for them to grow six to ten metres in height. Bananas will produce a full leaf each week in the summer growing season, and a fleshy stem after a certain number of leaves (usually about 30-40) have been produced. Flowering takes place at any time of the year, but is less likely in the winter months in New Zealand. A flower-bearing stem grows from the centre of the plant and bears a striking purplish-coloured tapered flower bud. Male and female structures are both present, but due to most common varieties being hybrids, the flowers set fruit without pollination taking place. Fruit maturation occurs 90-120 days after flowering, depending on cultivar. The resulting ‘spike’ of fruit can contain 10-30 kg of bananas, arranged in ‘hands’, from which supermarket-standard bunches are cut.

After fruiting, the stem is cut down to ground level, and a new sucker will arise from the base. Best practice is to keep three stems at various stages of growth, and remove all other ‘pups’ to prevent the plant from burning itself out. Commercially, plants are completely replaced every four to five years, but a well-cared for domestic plant should last longer.

In temperate climates, young plants may take up to three years to bear fruit, compared with a year or so under optimal growing conditions in the tropics. Propagation is most commonly by vegetative means, carried out by either

  • Taking cuttings 12-15 cm in length from the underground rhizomes which include three or more healthy buds and potting them on until a healthy root system develops. The buds will form the new plant’s shoots. Take these cuttings from a young plant that hasn’t yet flowered and from the end of the rhizome nearest the shoot for best results.
  • In the spring or summer (October to February), you can also dig up entire rhizomes with a young shoot attached. Pot on in suitable media until roots form, you can strip the older leaves away from the stem to direct energy into root development.

Currently, the most desirable method of obtaining healthy banana plants is to buy those produced commercially by tissue culture, which guarantees you are starting with disease-free stock, plus has the added advantage of the plants being of a verified, known variety.

Site selection and planting

Plant bananas in late spring, once the soil temperatures begin to rise. The ideal site for bananas is flat to gently undulating ground which is frost free, with free-draining soil, excellent shelter and a sunny aspect. Being securely fenced from livestock is necessary as stock find the leaves extremely palatable. In urban settings, planting near a house wall for additional shelter can be a good solution. Because banana stems are fleshy, without the lignified tissue that strengthens woody plants, they are prone to snapping when unsupported or grown in exposed conditions – something that is even more likely when a heavy fruit spike is added to the equation.

Wind wreaks havoc on banana leaves, with their admirable surface area (some varieties produce leaves up to three metres in length). They seem to be able to continue to function and grow even when the leaves are damaged and raggedy however. In terms of cold-tolerance, there is considerable variation between cultivars. Temperatures below -2°C can be tolerated for short periods, but anything lower than -4°C can cause irreversible damage to the underground rhizomes. The ornamental types and plantains are amongst the hardiest, anecdotally able to bounce back from frosts of around -7°C.

Culture and care

Bananas require good access to a range of targeted nutrients and plentiful water supply applied during their growing season. Although they are somewhat drought-tolerant, for reliable fruit production, adequate moisture is vital when the plants are fruiting. Because they are shallow-rooted, this becomes especially important if your soil type tends towards light and sandy. Very sandy soils are best avoided for this reason. Avoid heavy, cold and waterlogged soils as these sorts of conditions can lead to root disease and plant death. They are reasonably tolerant of coastal conditions if there is some shelter.

If you’re not already, make yourself familiar with the soil types present on your property, and their distribution before you start. Having a soil test done will help target the soil conditioning required to provide an optimal substrate for bananas if you plan on getting into growing them seriously. They are moderately heavy feeders throughout the growing season and will appreciate applications of compost, nitrogen and potassium-rich fertilisers including fish and/or seaweed preparations, and a thick layer of mulch (e.g. grass clippings) to protect those shallow roots near the soil surface. If not following an organic regime, approximately half a cup of a balanced general fertiliser such as Nitrophoska can be applied around the dripline of mature plants prior to rainfall, or watered in well after application.

Pruning

Current commercial practice sees banana plants maintained as a single-stem structure with all other suckers removed until after the plant has flowered for the first time. After this, a few other healthy suckers are allowed to develop and fruit in succession. This removal may not be of such great importance in the home garden. It is advisable to always cut down the spent fruiting stem after harvest, which, providing it is healthy, can be recycled as mulch material. Any maintenance regime should bear in mind the principles of all basic pruning – keeping the canopy open so air can circulate, reducing the risk of disease, and allowing optimum light penetration. Due to the nature of their composition, banana stems photosynthesise, so keeping dead foliage cleared away helps maximise this potential.

Pests, diseases and what to do about them

We are lucky in that New Zealand bananas are not affected by the pests and diseases of tropical crops that plague other countries.

The only known pest of bananas in New Zealand are pūkeko, which find the stem irresistible! Rats, mice and birds can also cause problems with fruiting bunches if these are left uncovered. Protecting developing bunches with 130 μm thickness re-usable bunch covers is best practice – a New Zealand-made version is now available. These covers have a UV-resistant coating, protecting the fruit from sunburn, and the thickness of the sleeve material protects the fruit from cold damage.

Special thanks to Geoff Mansell and Roslyn Norrie of Kotare Subtropicals for the following information on harvesting, ripening and selecting suitable banana cultivars for the New Zealand climate.

Harvesting techniques

Harvesting from the ground is preferable for health and safety reasons. Typically we use a saw, cutting gently some way up the fruiting stem and as the stem bows with the weight of the bunch, take the weight of the bunch on your shoulder or arms and lower to the ground. Use leaves previously removed and placed on the ground to rest it while you sever it from the stem. Leave a 20 to 30 cm stalk length at the top of the bunch for hanging. Then take the severed bunch, carry and place on a cushioned surface e.g. a lined wheelbarrow or transport vehicle deck with adequate cushioning material to avoid bruising. Take to the packing shed for hanging on a rack out of sunlight or covered with a bunch cover.

To harvest by ladder, locate the ladder under the bunch selected for harvest. Anchor the ladder with another person holding it securely. Partially climb the ladder to gently cut the back of the stem and reposition the ladder if necessary to enable you to guide the stem down to rest on top of the ladder. The ladder takes the weight of the bunch. Then with the aid of the person helping to take the weight, use a short pruning saw to sever the bunch from the stem. Carry and place on a cushioned surface and move to the packhouse for hanging out of the sunlight. 

Ripening

Imported banana bunches are taken off the stem when fruit are green and appear ¾ full (plump and not fully filled out) with banana skin ridges remaining. Removing the fruit at this time in their development halts the ripening process. Bananas are then removed from the plantation and processed, packed, then shipped in cool temperature-controlled containers. Once landed, they are inspected on arrival, and once they have passed a biosecurity inspection, are fumigated and stored at approximately 14° until scheduled for ripening based on store orders. When they are ready to be transported, the coolstore temperature is increased and held at 17°C and ethylene gas is added to speed the ripening process.

Outdoor-grown bananas for commercial supply in New Zealand are harvested when the ridges on the fruit have almost disappeared, and the fruit is plump. Our experience is that retailers prefer a mix of partially green-tinged yellow and yellowing fruit. Consequently, we keep an eye on the topmost hand to watch for a very slight colour change. Once we have plump green fruit that is just starting to change colour at the top we remove the bunch. The bunch is taken to hang on a banana rack with the fruit covered to prevent sun damage. We observe and wait until early ripening occurs across the top of the bunch, then de-hand, process, pack and deliver the fruit covered.

Varieties: Geoff and Roslyn’s top picks

The variety of bananas available in New Zealand mean there is a range of flavour profiles to choose from. Some bananas have citrusy flavours, others are creamy-tasting, and all are far more complex and appealing than the supermarket standard. Banana flowers and leaves are also a marketable component, with restauranteurs and home cooks alike keen to access these products. For reputable tissue-cultured banana plants shipped nationwide, visit https://www.kotaresubtropicals.co.nz/plants

Rajapuri – an Indian ‘lady finger’ type up to 2.4 m in height. Small bunches of very sweet fruit. Also suited for hot house growing. The only lady finger type harvested from the ground.

High Noon – High Noon is a favoured Australian selection growing 3.0 - 3.5 m in height. It’s similar to other Honduran varieties and has superior-flavoured dessert banana fruit on large bunches. The fruiting bunch hangs out at an angle to the pseudostem. It’s a hardy and robust plant but its fruiting stems must be propped.

Mona Lisa – a dessert Honduran hybrid banana. 3.0 - 3.5 m in height. Mona Lisa is a vigorous and strong grower with partially red pseudostems. Performs well in New Zealand with tangy sweet fruit.

Bonanza – Honduran hybrid banana; growing 3.5 - 4.0 m in height. It is marketed in Australia as Bananza. It produces higher-quality fruits in sub-tropical conditions. Highly recommended and well suited to growing in New Zealand in warmer frost-free areas. Pups of this variety are all sword-sucker like.

Goldfinger – Honduran hybrid banana; 3.5 -4.0 m in height. Hardy and robust. Very sweet, tangy, curved fruit. Black markings on stems, with broad, sometimes wavy leaves.

What to do with your crop

I’m not much help when it comes to dealing with banana gluts as I confess to preferring to eat the fruit fresh – I’m not a big fan of the ‘cooked banana’ flavour which some people go mad over. Apart from throwing overripe bananas in a smoothie, banana muffins or cake, the best use I’ve found for excess fruit is to blend them up with tart fruit such as unsweetened stewed plums or apricots and make fruit leather from them using my dehydrator. When my spike from conference started to get out of hand, I simply gave bags full away to grateful friends and neighbours!

Ditto goes for freezing extra ripe bananas for later use – the flavour when they thaw is off-putting to me, so even for smoothies and instant ice cream-type concoctions I’ll choose fresh bananas or pass. Chances are if you grow your own bananas, at some point the number of ripening fruit will overwhelm you, so I suggest you consult a guide such as Dish magazine’s compilation of 48 ways to use up leftover bananas.

Banana leaves are inherently useful as both a food wrap for cooking and for storage – find out more about this versatile, but often overlooked material here. Banana blossoms are a stalwart in Southeast Asian cuisine, where they are commonly added to soups, stews and curries. They have a soft and flaky texture and their most recent incarnation is as a vegan alternative to deep fried, battered fish.

If you are based in Northland and want to learn more about banana cultivation, Kotare Subtropicals founders Geoff Mansell and Roslyn Norrie provide two-hour classes on banana growing each year through the Community Education Whangārei programme, covering planning and design of your banana orchard/māra kai, nutritional advice, safe harvesting techniques, post-harvest care of fruit/storage tips and marketing. The courses usually run in September and November as part of the range of CEW's Spring Adult Community Education programmes – see www.cew.ac.nz if you are interested in learning more. The Bananas of New Zealand Aotearoa (BONZA) Facebook page is also a great place to start.


Anna-Marie Barnes is an active member of the New Zealand Tree Crops Association who endeavours to grow and preserve as much of her own fresh produce as possible. When the weather’s no good for gardening, she can usually be found inside working on a batch of homemade cheese or soap.

The New Zealand Tree Crops Association is a voluntary organisation promoting interest in useful trees, such as those producing fruit, nuts, timber, fuel, wood, stock fodder, bee forage and other productive crops. Find out more about the NZTCA here: https://treecrops.org.nz/

Disclaimer: the information supplied above is of a general nature and provided as reference material only. In regards to pest and disease control, please consult your agrichemical consultant for suitable products, application rates and further region-specific information.

Image credits
All images – Geoff Mansell