How to Propagate Longan

Fill a jar with lukewarm water and drop the longan seeds into it. Allow the seeds to soak in the water for 24 hours. Remove any that remain at the surface of the water as these aren’t viable. After the soaking period, pour the seeds into a colander or strainer and rinse them with cool water. Soaked seeds need to be planted immediately.

Fill the germination container with a soilless seed starting plant mix. Moisten the mix thoroughly before planting the longan seeds.

Push the longan seed into the soil no deeper than 3/4 inch. Planted deeper than this, the longan seed may produce more than one sprout, according to the late Julia F. Morton, author of “Fruits of Warm Climates.”

Place the heat mat in an area that receives indirect sunlight and set the temperature to 70 degrees Fahrenheit. Set the germination container on top of the mat.

Keep the soil moist without disturbing the seeds by spraying the surface with water or by placing the container in a pan of water that reaches halfway up its side -- a technique known as bottom watering. Remove the container when the top of the soil is moist.

Reduce the bottom heat gradually over the course of one week when the longan seeds sprout. Germination should occur within 10 to 30 days. Continue to keep the soil moist.