Any plant can be encouraged to grow and fruit faster, even garcinias. I had 2 mangosteens side by side of same age and under same conditions. Only difference is one was fertilized and the other not. Unfertilized tree was about 4 feet tall, the fertilized tree was 8 feet tall. Unfertilized mangosteens can take up to 20+ years to fruit. Some consistently fertilized mangosteens can fruit here in as little as 5 years, but usually take closer to 8.