What Are Jackfruit?
Jackfruit (Artocarpus heterophyllus) are the world’s largest and one of it’s most impressive tree-borne fruit. A single fruit could be as large as 90cm long by 50cm wide and can weigh up to 35kg. The fruit is covered in a soft spiky rind and is a light green colour that turns yellow when ripe.
The ripe fruit can be eaten fresh, preserved in syrups or even dried to make chewy jackfruit snack. The edible portion of the fruit comes in the form of bite sized arils. Each aril has a thick layer of sweet and juicy flesh surrounding a seed. If you have ever had juicy fruit gum that is exactly what it tastes like, sort of a mix between pineapple and banana. Even the seeds of the fruit are edible and taste very nice when fried with some salt and butter. Jackfruit can also be used raw when cooked in curries and is used as a meat substitute in many south Indian dishes. As a starch crop the unripe fruit is an invaluable food source for people in many areas of the tropics. Put simply Jackfruit is one of the worlds most versatile and useful fruits.
Jackfruit trees are almost as impressive as the fruit they produce. Trees are erect, evergreen and upright and grow throughout the tropics and subtropics of the world. Leaves are dark green, alternate, glossy and somewhat leathery. All parts of the tree contain a sticky white latex. The trees are also drought tolerant and extremely productive with any single tree being able to produce several hundred kilograms of fruit. If you want calorie production with a low level of care then look no further than the jackfruit.
Where Can I Get Jackfruit Plants?
Seedling trees are readily available in Australia from most nurseries with a focus on edibles. If you wish to grow your own seedlings simply pot up/plant a fresh seed and keep it moist. Within a month most seeds will have germinated if viable. The fresher the better when it comes to jackfruit seeds with germination rates dropping sharply as age increases. Generally seeds older than one month will have very poor germination rates. Seedling trees can fruit in as little as three years with favourable conditions. Many of the world’s productive jackfruit regions feature seedling trees exclusively and this I what I grow at Pobblebonk.
Seedling trees are variable with fairly average trees coming from great tasting fruit and vice versa. I am yet to find a seedling that wasn’t at least ok but grafted jackruit trees are preferable if you want to be sure of what you are getting. Grafted trees can be sourced from some of the larger fruit tree growers in Australia but stocks are always low so jump on them when they are available. In fact I have noticed a sever shortage of grafted trees the last few years and I may begin to produce some here at Boobook Farm to fill the gap.
Climate and Soil
Although essentially a tree from the tropical lowlands, jackfruit are quite hardy. In comparison to its less adaptable relatives, the cempedak and breadfruit, it can handle both colder and dryer environments. In Australia they grow best in the country’s north and along the coasts down to Sydney in the east and Perth in the west. At Boobook Farm we did get minor frost damage on the outer leaf margins the very first winter but have not seen it since. The canopy keeps away any frost now days. Unless you experience full days below zero degrees Celsius at your location then jackfruit should grow OK. The best temperatures for active growth are between 16 and 28°C.
Like almost all fruit trees you will read that it grows best in well drained, loamy, super perfect, amazingly unrealistic and enviable soil. Well yeah, it will. It will also grow in crappy clay like we started with. As long as water is not pooling around the trees roots and drowning it, it should do ok. Plants are hungry feeders and those that are fed often will grow a lot more quickly and bear more delicious fruit. Heavy feeding is also a good way to get trees growing quickly if grazers, or in marginal areas frost, are likely to be an issue. I place a thick layer of composted manure around the drip zone (outer leaves) of young trees roughly three times a year, skipping winter.
Size and SpacingJackfruit trees are huge! In their home tropical climate they grow up to thirty meters tall with an equally immense spread like that of a fig tree. They are an excellent shade tree in these climates. Outside the tropics though trees do not grow nearly as large and tree height is very easily managed with pruning. I have seen productive jackfruit trees kept to a height of two meters! Generally grafted jackfruit trees are easier to keep in check with regards to size. I prefer a little less work than 2 meter trees require and choose to keep my trees between four and five meters tall.
Spacing depends on the final height of the tree. Pobblebonk is a suburban permaculture site and so I space my trees about five meters from the closest ‘large’ fruit tree with plenty of inter-planting of compatible trees, shrubs and ground covers. In a traditional orchard with the space required to manage full sized trees you would need a minimum of 10 meters on all sides. I will add that jackfruit have large, strong root systems and so this is one of those trees that you do not plant right next to the house unless you are keeping it very small.
Management and Pruning
Jackfruit tree size is easily controlled through pruning. The most important aspect of pruning jackfruit is that you do it in the warm and wet time of the year. If you don’t do this you are going to have die back issues. I remember reading this and thinking I would try it anyway as half of what you read on the internet is just hearsay. Well I can tell you from experience, you will cause die back if you prune your jackfruit at the wrong time of year!
When pruning the technique will differ depending on the goal. Most growers usually want to bring down the height of the tree and this is done by removing vertical leaders. You can then control lateral branches for growth, being careful not to cut into the branch collars (the lump where the branch meets the trunk). Fruiting spurs from last years crop are also best removed as these will clutter up the inside of your tree. I could go on and on trying to make the pruning process clear but the below video from Dr Richard J. Cambpbell of Fairchild Tropical Botanic Garden does such a great job of demonstrating that I won’t.
FruitingMature jackfruit can produce between 20 and 250 fruit per year. Unless you have a place to sell them, you do not want 250 jackfruit. Thankfully though pruned trees tend to have less fruit (yield is somewhat relative to tree size) and of a higher quality. Trees generally flower in the spring and early summer in the subtropics. Flowers grow and a fruiting spur which generally has two male flowers before then growing a fruiting female flower. The fruit take from six to eight months to mature.
Jackfruit is traditionally cultivated by seeds and because of this there is a large variety in fruit shape, size, taste and texture. Generally though jackfruit can be classified as one of two main types with several varieties of each available. These are known as the soft flesh and the crisp jackfruit. People almost always have a strong preference for one or the other types of fruit.
Softer fleshed varieties. These taste wonderful but I tend to prefer the texture of crisp varieties. In saying that I have friends that prefer the soft so you are going to have to try them for yourself to figure out what you like.
My favourite type of Jackfruit! These have a crisp, crunchy flesh that bursts in the mouth.
Pests and Diseases
Jackfruit has very few pests. If you drown the roots you can encourage root rot but this is uncommon in Australia. Growers elsewhere also have issues with borers and blossom and fruit rot. I have not had any of these issues in South East Queensland. I have seen scale insects on trees here but the issue has always resolved itself quickly without intervention. Jackfruit are remarkably hardy trees.