Mangosteen, known botanically as Garcinia mangostana, is an extremely slow-growing, ultra-tropical, fruit-bearing tree. Mangosteen's environmental requirements are so stringent its cultivation is not widely undertaken outside of its native habitat in tropical Southeast Asia. Growing mangosteen from seed can be accomplished with varied success, as environmental conditions must be consistently maintained for the 12 to 20 years it takes to bring a mangosteen seed up to a mature, fruit-bearing tree. Mangosteen plants do not tolerate re-planting well, so plant the seed in soil in the ground or in a container space large and sturdy enough that it need not be transplanted for three to five years.

...

Select plump, fully developed seeds from ripe fruit for planting. Mangosteen seeds must be removed from the fruit no more than a few days before planting. Seeds that are purchased are usually shipped in damp peat moss or sphagnum moss in airtight containers or bags. Soak your seeds in clean water for 24 hours before planting to speed germination.

Plant the fresh mangosteen seed at least 8 inches deep in rich, organic, sandy loam-amended soil with organic compost. The soil should be a minimum of 4 feet deep. Sprouting typically takes 20 to 22 days and is complete in 43 days. The young saplings take a minimum of two years to grow to 12 inches in height. After the sapling reaches a minimum of 2 feet, you can carefully transplant it, if absolutely necessary.

Regulate the temperature closely, providing temperatures above 50 degrees F and below 100 degrees F at all times. Shelter the mangosteen seedling and sapling from any gusts or winds.

Provide filtered sunlight or partial shade exposure for up to 13 hours per day.

Water the mangosteen consistently, keeping the soil moist at all times. Provide environmental humidity for the seed, sapling and mature trees at the equivalent to an annual rainfall of at least 55 inches. Use only fresh water and do not allow the mangosteen to be exposed to salt water or saline heavy tap water, such as softened water.