Jackfruit (Artocarpus heterophyllus) excels in a tropical or subtropical climate. It’s food security on a stick. They produce edible, protein-rich seed and fruit which can be used and stored in many ways and at different stages of ripeness. This year, my seven year old tree is carrying 150 fruit, which is about average. Don’t ask – how big do they grow? Do ask – how can one be trained in a small garden? Defintely ask – how best to clean utensils?

Why jackfruit?

I grow jackfruit because it crops heavily at an early age and it produces fruit and seed which are versatile in cookery. Think smoothies, ice cream, dried fruit, frozen fruit, fresh fruit, boiled seed, fried seed, frozen seed, seed as flour, or young fruit cooked or bottled in brine as a vegetable alternative to artichoke hearts.

Yesterday, Thuan made young jackfruit salad Vietnamese-style for lunch. This is his mother’s favourite, prepared with dry fried sesame seed, lime juice and coriander. Later, I pureed young jackfruit with sun-dried tomatoes, ricotta and sour cream and, seasoned to taste, served it with corn chips. We had ripe jackfruit smoothie with almond milk. This morning we had young jackfruit in a stir fry with home grown beans, tomatoes, egg and spring onion with cashews and noodles.

Don’t ask – how big do they grow? Do ask – how can one be trained in a small garden? Jackfruit can be trained as espaliers. I keep mine as a small tree. I removed the top of the leading shoot when it reached a height suitable for safely picking fruit from a step ladder. I shorten the lateral shoots to balance the tree, giving it a rounded crown.

My tree started as a fruit, a gift from Rosa, a local Vietnamese gardener who’s jackfruit trees I spotted seven years ago. I sowed the seed on 22.2.13, immediately they were removed from the fruit. Do not let seed dry out – you can’t save their seed for long as they are ready to grow at maturity. They germinated in 24 days.

I planted five seedlings along a north facing fence the following spring. Seedlings 1 and 3 formed the most shapely, well branched seedlings. The others were culled when 18 month old.

Seedling 3 produced its first male flowers at ten and a half months old on 27.1.14. My first crop. I culled seedling 1, which didn’t flower that year.

Seedling 3 produced its first three fruits on 17.8.15; the best weighed 9kg.

Jackfruit normally start cropping well in the tropics at eight years old. In 2018, when five years old, my seedling 3 produced 32 fruit around 9-10kg each in subtropical Brisbane. This illustrates the value of choosing the right location and care.

In 2019, ring tailed possums destroyed two thirds of the female fruit. Just 14 survived to reach harvest.

This year there are 150 fruit. All are bagged. That’s 50 x 10kg fruit for ripening and 100 x 1kg green fruit for use as your would artichoke hearts.

Growing jackfruit

Jackfruit are composed of hundreds to thousands of individual flowers, and the part we eat are the fleshy petals and the seed they enclose.

They are warm climate trees, cultivated worldwide in the tropics and subtropics. They accept a range of soil types from acidic to slightly alkaline, but the soil must be deep. While they benefit from irrigation in dry conditions, they must have good drainage.

Jackfruit need full sun. However, their seedlings germinate on a forest floor and therefore freshly planted jackfruit need a little shade protection, like a temporary covering of shade cloth, during extremely hot days in the first summer.

While jackfruit will fruit all year round in the tropics, fruiting is seasonal in the subtropics occurring from late winter to the end of summer. Late fruit that ripen during autumn may be poor quality. Regular watering during hot, dry, windy weather and feeding with poultry manure – a complete organic fertiliser – once each season is advisable. I give my tree recycled wastewater.

Trees are dioecious, with male and female flowers appearing separately and being distinctly and unmistakably different. They are wind pollinated. Male flowers are small and short lived.

Working with jackfruit

Damage the skin of a fruit, or cut a stem during pruning or harvesting, and you’ll discover they defend themselves by exuding a sticky white latex. It’s perfect for glueing together the mandibles of a grasshopper. Protect your hair and eyes from this sticky latex if you prune a tree while standing underneath it. Use eucalyptus oil to clean pruning equipment and cooking utensils.

Beware possums

In Australia, young female flowers are eaten or damaged by both ringtail and brushtail possums. In northern Queensland and New Guinea common cuscus also harm the fruit. Protect individual fruit by enclosing them in mesh bags (which can be purchased on line) or grow trained trees under shade cloth. At a pinch, wrapping pantyhose around fruit discourages possums. Nibbled fruit will continue to develop, but fail to fully mature. Once the skin thickens, possums lose interest in them, so when fruit outgrow their bags, remove the bags and save them for next year.

Cultivars

Jackfruit cultivars may produce fruit that are very soft and sweet, or crisp and less sweet. There are many cultivars, some only being used unripe in curries, but only the crisp or the soft, sweet cultivars are found easily in Australia.

Harvest

You can tell when a fruit is ripe and ready to pick by gently tapping fruit with a stick and learning how the sound changes. A full sized but unripe fruit makes a loud, clear sound when tapped, but a ripe fruit makes a dull sound. Soft, sweet cultivars ripen rapidly in a matter of hours and during this brief period their ripe aroma is obvious. If you are away from home when this happens, expect fruit to attract flying foxes. Fallen fruit attract rats.

Young male flowers can be boiled, dipped in lime juice, and then dipped in chilli powder and salt.

Everyone says jackfruit seed are protein rich and can be boiled and taste like sweet chestnut. This is true; jackfruit seed contain between 6-7% protein. What they don’t say is allow boiled seed to cool and then remove the seed coat so eating them is enjoyable. Boiled seed can be dried and ground into flour and used in baking. They are used to make biscuits. Try using them as a base for cheesecake.

Boiled, peeled seed can be fried and then they taste more like roast peanut. Try adding vinegar (balsamic vinegar) and then seasoning them with salt and chill powder.

Boiled young fruit, picked when they weight at least 1kg, can be cored and peeled and used as a green vegetable or bottled in brine. Vegans use them a lot and in South Asia special cultivars are grown specifically for use in curries. The texture is said to resemble chicken breast. I find the flavour and texture is much more like boiled artichoke hearts. Suddenly, every recipe in which artichoke hearts can be used can be used with  jackfruit. Handy!

Small wonder the jackfruit is the national fruit of Bangladesh and Sri Lanka. Native to the lowland tropics of South and South East Asia, this evergreen tree is a vital part of home food security. They are related to mulberry, figs and breadfruit but have very strong, rot-resistant timber. Jackfruit is traditionally used in housing and temples as load-bearing supports. The trees have fibrous root systems, so they are useful in reducing soil erosion by storm water and also for stabilising riverbanks.

Jackfruit famously produces the largest compound fruit of any tree in the world; potentially they can weigh 50kg, which is why reducing the length of lateral shoots in a home garden is wise. Less risk of branch collapse during a storm. More commonly the fruit weigh much less, especially in a dry subtropical climate like mine. But it is still important to maintain the tree at a safe picking height so it is simple to place and remove protection bags from fruit.

Mature trees, that grow freely in the wet tropics and receive plentiful rain can produce up to 500 fruit a year. I have added this hyperlink so you can get an idea of how incredibly productive this species can be – if you have a little help from your friends.

Jerry Coleby-Williams
Director, Seed Savers’ Network Inc.
31st August 2020