Was the exposure to sunlight direct? Did you add anything to their pots? What kind of water are you using? I have one on my patio thats always outside and it gets filtered sunlight underneath a large magnolia. I wouldn't say its the best looking plant but it is growing, rather than declining...albeit extremely slow. I have seashore mangosteens next to my purple mangosteen and they are nearly 4ft. tall and pushing massive growth presently. Not sure temps or humidity are the problem. My 2cents. Chris
p.s I give them all filtered water.