Many tropical fruit seeds are recalcitrant, which means that they have a short storage life and lose viability quickly if they dry out after being removed from the fruit. Typically, tropical fruit seeds need to be planted immediately or stored moist for relatively short periods of time (several days to several weeks).
For planting purposes, tropical fruit seeds can be classified into three groups. Each group has its own planting requirements:
1. Extremely tiny seeds (like Jamaican strawberry and hairy camasey) – Tiny seeds should be surface-sown on a pre-moistened 1:1 peat:perlite mix. Cover the entire pot with a plastic bag and make small holes in the bag for air exchange. Keep the pot in approximately 50% shade in a warm (70-90F) place and make sure that the mix doesn’t dry out. When the seeds germinate, tiny green specks can be seen on the surface of the mix. At that point, slightly enlarge the holes in the plastic bag and give the plants more light, but not full sunlight. When the plants have 2-3 true leaves, they can be carefully transplanted to individual containers in a mix of 1:1:1 peat moss:perlite:compost or a well drained soil mix.
2. Firm to hard seeds of different sizes (most tropical fruit seeds) – Plant the seeds separately in cell trays, pots or growbags in a 1:1 peat:perlite mix at a depth approximately equal to the diameter of the seed. Maintain the mix evenly moist but not waterlogged and keep the containers under 50% shade in a warm (70-90F) place. Some seeds germinate relatively quickly, in 2-3 weeks, while others can take several months. If the seedlings are in cell trays or small pots, they should be transplanted to larger pots or growbags in a 1:1:1 peat moss:perlite:compost mix or well drained soil mix when the root ball is firm and well filled with roots.
3. Large, fleshy seeds (like jackfruit, Malay apple, cacao and rambutan) – These seeds are very perishable and must be planted as soon as possible after removal from the fruit. Since they contain a high percentage of water, they are very susceptible to rotting if the mix is too wet or if they are planted too deeply. They are best planted flat on the surface (or only partially covered) of a very well drained mix with at least 50% perlite or coarse sand, in individual containers. Maintain the mix moist but never waterlogged, and keep the containers in 50% shade and in a warm (70-90F) place.
Once the seedling trees have 2-3 true leaves, they can be fertilized every 2-3 months with a dilute solution of 20:20:20, fish emulsion or equivalent liquid fertilizer, or with a slow release fertilizer. As the trees get older, they can be hardened off by decreasing the shade to 20-30% before planting out in the field.