Jackfruit is a tropical fruit that is a dieatary stable in many tropical areas of the world. It is grown in Florida and Hawaii. The fruit is the worlds largest fruit - not uncommon for one jackfruit to weigh 50 - 80 POUNDS (yes - ONE fruit) Seeds are usually the method of propagating trees for production.
Obtain a fresh seed. You can sometimes purchase pieces of jackfruit at asian markets. I bought a small piece at Uwajimayas in Seattle (uwajimaya.com ) Even though the seeds are LARGE (3" long) a small piece of fruit had seven seeds in it (plus the produce guy had given me a seed from the sample right before I decided to purchase a piece)
Take the fresh seeds and place in a container filled 3/4 with a mixture of seed starting mix and sand. Cover the rest of the seed with the mix. Water thoroughly. Even cracked seeds will sprout if they are otherwise intact. Of my eight seeds, two were cracked, and all eight are growing into plants.
Keep warm until the seeds germinate - 1-2 weeks then as they grow, make sure they get plenty of light. Keep moistened but not wet. Jackfruit do not like soggy soil for any length of time but they like drying out even less.
Jackfruit have delicate taproots and it will be necessary to transplant into larger containers regularly being careful to not harm the taproot. When they get older, Jackfruit can tolerate a LITTLE frost otherwise they will need to be brought in to a cool to warm greenhouse (warm is best - cool will allow it to survive) They also make decent house plants. They could also permanently live in a greenhouse. Jackfruit can go outside for the summer months.
Fertilize Jackfruit once a month when they are actively growing. Remember to not let it dry out at any time.